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Rough idle / Multiple Cylinder Misfire

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Old 06-16-2006, 02:32 PM   #1
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Rough idle / Multiple Cylinder Misfire

hey everyone.

Hope someone can shed some light on this desperate situation..

Having a a major dilema with a rough idle / Multiple Cylinder Misfire on my 2001 Chevy S10. Its a V6 4.3L with 100K miles on it. The first sign of the problem was the service engine light would blink intermittently when driving on the highway or revving the gas. The blinking would stop after a few minutes and the light would go away. This same episode happened in 4 times within a week until the light eventually stayed on steady while driving down the parkway. I was not concerned until i slowed down and noticed the truck running rough and bogging out. I made it home that day with all the shakiness and wobbling down the road, especially at a stop light where it felt like it was gonna stall out.. Got it diagnosed and a code P0300 came up which is a multiple cylinder misfire but was told it can be due to many things so we have to rule out different things until reaching the culprit. A friend mechanic said he is almost sure it is the spider injector assembly but not a guarantee. So i started on the mission and here is what has been replaced and checked so far....

REPLACED THE DISTRIBUTOR CAP AND ROTOR, SPARK PLUGS, WIRES, O2 SENSORS, FUEL FILTER, AND CHECKED OTHER COMPONENTS SUCH AS THE EGR VALVE, CATALYTIC CONVERTER AND ALL HOSES FOR LEAKS, NOTHING FOUND.

I DONT KNOW WHAT ELSE TO REPLACE BESIDES THAT SPIDER INJECTOR ASSEMBLY WHICH IS PRETTY EXPENSIVE...AND I DO NOT WANT TO SPEND MONEY IF THERE IS A CHANCE IT CAN BE SOMETHING ELSE I AM OVERLOOKING.

IVE BEEN IN A SLUMP FOR THE PAST MONTH WITH THIS PROBLEM AND ITS ONE DISAPPOINTMENT AFTER ANOTHER WHEN EVERYTHING IVE REPLACES IS NOT THE ISSUE. I CAN DO THE LABOR ON THE VEHICLE I JUST NEED TO KNOW WHAT IT IS THAT NEEDS TO BE FIXED TO RESOLVE THE ISSUE.

THANK YOU IN ADVANCE FOR ANY ADVICE.
Old 06-19-2006, 05:46 PM   #2
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Re: Rough idle / Multiple Cylinder Misfire

Old 06-19-2006, 07:14 PM   #3
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Re: Rough idle / Multiple Cylinder Misfire

a worn distributor gear was the cause of my multiple cylinder misfire

have you done a seach about this problem? I know there are atleast 2 threads about this, and one is a 2 pager with some info.

Last edited by Flamed 98; 06-19-2006 at 07:16 PM.
Old 06-19-2006, 07:22 PM   #4
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by ga76velez
hey everyone.

Hope someone can shed some light on this desperate situation..

Having a a major dilema with a rough idle / Multiple Cylinder Misfire on my 2001 Chevy S10. Its a V6 4.3L with 100K miles on it. The first sign of the problem was the service engine light would blink intermittently when driving on the highway or revving the gas. The blinking would stop after a few minutes and the light would go away. This same episode happened in 4 times within a week until the light eventually stayed on steady while driving down the parkway. I was not concerned until i slowed down and noticed the truck running rough and bogging out. I made it home that day with all the shakiness and wobbling down the road, especially at a stop light where it felt like it was gonna stall out.. Got it diagnosed and a code P0300 came up which is a multiple cylinder misfire but was told it can be due to many things so we have to rule out different things until reaching the culprit. A friend mechanic said he is almost sure it is the spider injector assembly but not a guarantee. So i started on the mission and here is what has been replaced and checked so far....

REPLACED THE DISTRIBUTOR CAP AND ROTOR, SPARK PLUGS, WIRES, O2 SENSORS, FUEL FILTER, AND CHECKED OTHER COMPONENTS SUCH AS THE EGR VALVE, CATALYTIC CONVERTER AND ALL HOSES FOR LEAKS, NOTHING FOUND.

I DONT KNOW WHAT ELSE TO REPLACE BESIDES THAT SPIDER INJECTOR ASSEMBLY WHICH IS PRETTY EXPENSIVE...AND I DO NOT WANT TO SPEND MONEY IF THERE IS A CHANCE IT CAN BE SOMETHING ELSE I AM OVERLOOKING.

IVE BEEN IN A SLUMP FOR THE PAST MONTH WITH THIS PROBLEM AND ITS ONE DISAPPOINTMENT AFTER ANOTHER WHEN EVERYTHING IVE REPLACES IS NOT THE ISSUE. I CAN DO THE LABOR ON THE VEHICLE I JUST NEED TO KNOW WHAT IT IS THAT NEEDS TO BE FIXED TO RESOLVE THE ISSUE.

THANK YOU IN ADVANCE FOR ANY ADVICE.
I would have gone for the spiders...that's what my miss turned out to be. GM replacements at www.getgmparts.com
Old 06-20-2006, 05:45 PM   #5
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Re: Rough idle / Multiple Cylinder Misfire

well thank you! i will investigate through that end and see what happens. i have looked through the other threads with the same problem and pretty much its pointing towards the spider.
Old 06-20-2006, 06:33 PM   #6
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Re: Rough idle / Multiple Cylinder Misfire

it is the worn disturbitor gear... it happened to me, i got 2 tune ups in a year and it was still doing it.. then i got the whole distributor and now its been runing great for 15,000 miles
Old 06-20-2006, 06:37 PM   #7
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by ga76velez
well thank you! i will investigate through that end and see what happens. i have looked through the other threads with the same problem and pretty much its pointing towards the spider.
i think it is the gear... trust me i had the exact same problems... the blinkin the bogging u can find out if it is the gear simpily by removing the cap and checking lash on the distributor. it shouldnt move at all
Old 06-29-2006, 08:29 AM   #8
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Re: Rough idle / Multiple Cylinder Misfire

thank you so much for the input.. so far i am trying to remove the spider injector assembly to see if it looks fried. also looking into the distributor gear as well. i dont want to buy a part that would not be the cause of the problem so i have to be at least 95% sure its either the distributor gear or the spider injector assembly.
Old 06-29-2006, 08:52 AM   #9
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by ga76velez
thank you so much for the input.. so far i am trying to remove the spider injector assembly to see if it looks fried. also looking into the distributor gear as well. i dont want to buy a part that would not be the cause of the problem so i have to be at least 95% sure its either the distributor gear or the spider injector assembly.
Visual inspection may not reveal anything. Hope it's the cheaper option...
Old 07-02-2006, 06:28 PM   #10
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Re: Rough idle / Multiple Cylinder Misfire

took out the distributor cap and you can move the rotor around....but not by much.. it doesnt rotate all the way but it moves... is that a bad thing??? i couldnt not find any specs online to see if the rotor/cap is supposed to even move.. or be tight. so thats one thing. taking out the cpi unit as well today.. i am stuck in two different scenarios... a fuel problem.. or electrical problem.... arggghhhh!!!!!!!!!
Old 07-03-2006, 12:03 AM   #11
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Re: Rough idle / Multiple Cylinder Misfire

these two threads r having same simptoms

http://www.s10forum.com/forum/f107/on-throttle-bogging-down-257312/
http://www.s10forum.com/forum/f107/ho2s-sensor-count-and-location-257230/

please let us know if you have any success
Old 07-03-2006, 02:31 AM   #12
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Re: Rough idle / Multiple Cylinder Misfire

Mine would occationally throw this code when my MAF was acting up (while i was beating on it a little).Did something similar to what you described. SES light would come on, on occation while driving. Didnt make any difference though. Only once or twice when I was beating it & the maf was going goofy did it throw that code.

I swapped the MAFs out & it was fine. I recently cleaned the same MAF ( the little bumps between the wires on the sensor itself were caked with dirt)& put it back in & the original is not acting up anymore. Wouldnt hurt to clean it off. Get eletrical contact cleaner, Take the maf out and take off those aluminum ends(think its a t20 torx bit), & give the little metal peices a good cleaning.

I have heard of the injector unit, or the poppets for that matter getting dirty & sticking causing that code also. It would be expensive to get the injector new (if that is the problem), but here on ebay you can get the whole manifold for less than half of the oem injector cost. Comes with the injector and everything.

http://cgi.ebay.com/ebaymotors/GM-CH...02308641QQrdZ1

hope this helps in some way.
Old 07-03-2006, 07:42 AM   #13
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Re: Rough idle / Multiple Cylinder Misfire

Tx For The Information. Well, I Took Out The Spider Injector Unit Yesterday. Very Gunky, Corroded, And Carbonized All Over. By What It Seems Its A Vortec Csfi With The 6 Injectors And The Regulator. I Am Getting A New Replacement Unit And See What Happens. If This Is A No Go Then I Am Gonna Check Out The Distributor Gear. This Has Been 3 Months Of Torture In Trying To Figure It Out. I Will Keep You Posted Of The Process And Outcome For Future Reference For Anyone That Goes Thru The Same Ordeal.
Old 07-03-2006, 09:41 PM   #14
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Re: Rough idle / Multiple Cylinder Misfire

Mine is doing the same thing, it has thrown the codes O2 Heater Sensor & Misfire in 4th Cylinder. New plugs, wires, cap, router, coil, starter. My truck usually does it at night when I am driving home about 55 to 65 it feels as I describe it as hauling a trailer with animals in it and when they move it tugs. I am at my wits end. I love my SS but its a pain in the rear. Just today I replaced the lower ball joint on the drivers side. If I see that guy that owned it before I would beat the snot out of him for treating this truck the way he did. He had no respect for it.
Old 07-06-2006, 09:49 PM   #15
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Re: Rough idle / Multiple Cylinder Misfire

ok.. here is the update... my fuel injection unit is the one that u dont have to replace the whole unit.. its those newer ones that came out after the late 90's. so i got the fuel regulator today since the old one was leaking obviously. replaced the old one with the new one and installed the unit again and started the truck.. definately less roughness with the idle and more power and still bogging but less. the service engine light comes on after i press on the gas and blinks then pauses.. then starts up again.. but no steady light. definately still having a misfire.. UGH!!!! i dont know if i have to wait for the whole conjunction to stablize or something else is triggering it.. my thought is one of the fuel injectors is bad.. could be possible.. replacing the regulator made a 40% difference but something is still off. gonna try to drive to autozone to get it diagnosed with the code and hopefully its not the same P0300 but a more specific one.. i am hoping it leads me to a bad injector or something else besides the misfire code crap.. almost 3 months and very little progress so far. i am losing hope and the worst part is still owing 14k on it. this really bites. gonna keep trying to get to the problem and i will keep posting updates. hope this helps for anyone going thru the same thing.
Old 07-07-2006, 07:18 PM   #16
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Re: Rough idle / Multiple Cylinder Misfire

okie dokie.. just realized today the timing is off by an inch... gonna work on the distributor today.. take it out see whats going on.. cylinders 3 and 5 are flooded with gas because the sparks arent firing in the correct order.. its just one big glorious mess! see what happens and will keep posted.
Old 07-11-2006, 09:23 AM   #17
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Re: Rough idle / Multiple Cylinder Misfire

here is my daily update... checked distributor gear/shaft.. looks good.. the timing is very off and now its backfiring.. by what i researched you cant adjust the ignition timing manually because it is controlled by the electronic control unit (ecm).. so what to do?? by what i speculate the computer is stuck on stupid and firing sparks and timing to what it thinks its correct and there is no way to modify it. i am so confused with the problem. any feedback or insight would be very much appreciated. still the same problem with the misfire and now the timing is bonkers.
Old 07-18-2006, 09:27 AM   #18
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Re: Rough idle / Multiple Cylinder Misfire

the situation still sucks. blah. took the truck to autozone and got the codes.. was showing MAF sensor malfunction.. so happy but replaced the part and still the same stupid problem... tested again.. now the cam sensor showed up... realized it was disconnected.. ok... maybe it will be fine now after i plug the stupid thing on.. wrong.. actually got worse when the cam sensor was plugged in... started misfiring like crazy and the code P0300 came up which was the same code showing up when this whole problem started!!!!! so now what??? got home with the truck in worse condition than before i checked the codes and plugged that cam sensor... which is very confusing.. whats the link with the misfire an the cam sensor.....????????
Old 07-18-2006, 10:02 AM   #19
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Re: Rough idle / Multiple Cylinder Misfire

ok, here is what i recently found
--------------------------------------------------------------------------------

File In Section: 06-Engine Emissions

Bulletin No.: 99066F

Date: March, 2003

SPECIAL POLICY

SUBJECT:
99066F - SPECIAL POLICY ADJUSTMENT - SEQUENTIAL CENTRAL PORT
FUEL INJECTION (SCPI) FAILURES IN CALIFORNIA ONLY (YF5
EMISSION EQUIPPED)



MODELS:
CERTAIN 1996, 1997, 1998, 1999, 2000, 2001, 2002 S/T, M/L, C/K, G,
P, W4/NPR TRUCKS AND 2003 NPR TRUCKS EQUIPPED WITH 4.3L
(RPO L35 - VIN CODE W OR RPO LF6 - VIN CODE X), 5.0L (RPO L30
- VIN CODE M) OR 5.7L (RPO L31 - VIN CODE R) ENGINE AND
CALIFORNIA EMISSION EQUIPPED (RPO YF5)



This bulletin is being revised to add the 2002 and 2003 model years to the SCPI Special Policy on certain S/T, M/L, C/K, G, P and W4/NPR truck models. Please discard Special Policy Bulletin Number 99066E, dated February, 2003.

CONDITION

Some customers of 1996, 1997, 1998, 1999, 2000, 2001, 2002 model year S/T, M/L, C/K, G, P, W4/NPR trucks and 2003 NPR trucks, that are registered in California, equipped with 4.3L (RPO L35 and VIN Code W, or RPO LF6 and VIN Code X), 5.0L (RPO L30 and VIN Code M) or 5.7L (RPO L31 and VIN Code R) engine, and California emissions (RPO YF5), may experience a "Service Engine Soon" light, misfire, rough idle or hard start due to a deposit build-up on the Sequential Central Port Fuel Injector (SCPI) poppet valve(s). The deposit build-up may cause injector poppets to stick closed. Certain fuels have been found to interact with the SCPI system to cause the deposits.

SPECIAL POLICY ADJUSTMENT

This special policy covers the SCPI failure condition described above for a period of ten (10) years or 200,000 miles, whichever occurs first, from the date the vehicle was originally placed in service, regardless of ownership.

The repairs will be made at no charge to the owner. This special policy applies ONLY to repairs requiring SCPI system servicing, injector cleaning and/or MFI assembly replacement of the SCPI system. The customer should not be charged for performing a system check when it is determined that the SCPI system is not the cause of a customer complaint (labor operation T5532 is provided to submit claims for such system checks). Any additional necessary diagnosis and repairs that are not related to the SCPI condition are not covered by this special policy. The customer should be informed that any further service that is not covered by new vehicle warranty will not be covered by this policy.

VEHICLES INVOLVED

Involved are certain 1996,1997,1998,1999, 2000, 2001, 2002 S/T, M/L, C/K, G, P, W4/NPR and 2003 NPR model vehicles, registered in California, equipped with 4.3L (RPO L35 - VIN Code W, or RPO LF6 - VIN Code X), 5.0L (RPO L30 - VIN Code M) or 5.7L (RPO L31 - VIN Code R) engine; and California emissions (RPO YF5). This Special Policy covers all vehicles within these model years, with these engine and emissions RPO's.

PARTS INFORMATION



Parts required to complete this special policy are to be obtained from General Motors Service Parts Operations (GMSPO). Please refer to your "involved vehicles listing" prior to ordering parts. Normal orders should be placed on a DRO Daily Replenishment Order. In an emergency, parts should be ordered on a CSO = Customer Special Order.

IMPORTANT :Isuzu Parts Ordering: In order to comply with the 10-digit Isuzu part numbering system, Isuzu dealers must add an "8" to the beginning and a "0" to the end of the listed 8-digit part numbers when ordering parts through AIPDN.



CUSTOMER NOTIFICATION






Customers will be notified of this special policy on their vehicles by General Motors (see copy of typical customer letter included with this bulletin - actual divisional letter may vary slightly).

SERVICE PROCEDURE

System Check: Use strategy-based diagnoses listed in the front of the Driveability and Emissionssection of the service manual. If the SCPI system is operating properly, inform the customer that the vehicle does not have the condition listed in the owner letter. If poor driveability conditions persist, inform the customer that any further diagnosis and repairs will be at their expense if the vehicle is outside the parameters of the new vehicle warranty.

SCPI Injector Cleaning Procedure: If diagnosis leads to sticking poppet nozzles, use the service procedure from Service Bulletin 00-06-04-003B to clean the SCPI poppet nozzles. Please note that the service bulletin term for SCPI is Central Sequential Fuel Injection (CSFI), but is referring to the same fuel system assembly. If the poppet nozzles have previously been cleaned and the sticking condition has reoccurred, refer to the correction paragraph below.

SCPI Fuel Tank Fill Pipe Assembly for 1997-99 M/L Van and 1999 - some 2000 C/K Truck: with 4.3L, 5.0L, 5.7L engines and built prior to listed VIN/Production dates on Service Bulletin 00-06-04-018: If diagnosis leads to sticking poppet nozzles on these models, use the service procedure from Service Bulletin 00-06-04-018 to replace the fuel tank fill pipe assembly, if this procedure has not been performed previously. Previous service procedure can be verified by checking GMVIS for Labor Operation L1065 on "M/L" trucks with replacement part number 15050573; or Labor Operation L1065 on "C/K" trucks with replacement part numbers 15747585 or 15747588.

Correction: If, after cleaning the SCPI poppet nozzles, the normal service manual diagnosis still indicates that the SCPI is the cause of the customer complaint, or if the injectors have previously been cleaned and the vehicle has again experienced sticking poppet nozzles, refer to Service Bulletin 00-06-04-003B and replace the SCPI fuel assembly with the MFI fuel assembly. Please note that the service bulletin term for SCPI is Central Sequential Fuel Injection (CSFI), but is referring to the same fuel system assembly.

CLAIM INFORMATION



For vehicles repaired under this special policy, submit a claim with the information indicated.

CUSTOMER REIMBURSEMENT

Customer requests for reimbursement are for any previously paid repairs to, or replacement of, the Sequential Central Port Fuel Injection (SCPI) system. Repairs must have occurred within 10 years of the date the vehicle was originally placed in service, or 200,000 miles, whichever occurs first. The requests are to be submitted within two (2) years of the date on which the repair was paid or within two (2) years of the date of this Special Policy Bulletin, whichever is greater.

When a customer requests reimbursement, they must provide the following:

-Proof of ownership at time of repair.

-Original paid receipt confirming the amount of unreimbursed repair expense(s) (including Service Contract deductibles), a description of the repair, and the person or entity performing the repair.



Customers from the State of California, must submit requests for reimbursement directly to (Divisions) per instructions in the owner letter.

If the work was done by someone other than a GM dealership, the amount of reimbursement will be limited to the amount that the repair would have cost GM to have it completed by a GM dealership.
__________________

In other words, because California sued GM, they get it free. The rest of us pay.
Old 07-20-2006, 08:33 AM   #20
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Re: Rough idle / Multiple Cylinder Misfire

thanks for the info... very frustrating situation.. its probably gonna end up being something dumb or something really bad.. right now i am trying to determine if the misfire is fuel related or ignition distributor issue. very hard to define especially when u dont have access to all the gadgets to run the tests.. i really got confused after they scanned the codes at autozone.. how can the mulitple cylinder misfire come up on the third time they scanned it and it wasnt there before.. the maf sensor was the only code coming up.. fix that.. then the cam shaft sensor code comes, fix that... than thats when the misfire starts... why why why??? the scanning of the codes really didnt do much for me.. they should have newer ones to pinpoint the problem directly so you wont waste your time buying parts to fix the code and then trigger another one.. if thats the case, i will always get a code and something will always have to be replaced.. grrrrrrr
Old 07-20-2006, 11:00 PM   #21
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by ga76velez
thanks for the info... very frustrating situation.. its probably gonna end up being something dumb or something really bad.. right now i am trying to determine if the misfire is fuel related or ignition distributor issue. very hard to define especially when u dont have access to all the gadgets to run the tests.. i really got confused after they scanned the codes at autozone.. how can the mulitple cylinder misfire come up on the third time they scanned it and it wasnt there before.. the maf sensor was the only code coming up.. fix that.. then the cam shaft sensor code comes, fix that... than thats when the misfire starts... why why why??? the scanning of the codes really didnt do much for me.. they should have newer ones to pinpoint the problem directly so you wont waste your time buying parts to fix the code and then trigger another one.. if thats the case, i will always get a code and something will always have to be replaced.. grrrrrrr
Having a similar problem and finally gave up and am taking it to my friend who is a GM mechanic. just on a quick look he seems to think that it is a bad coil. he said that this is not uncommon for a 4.3 to throw a multiple cylinder misfire code when the coil starts going. He is taking it in for me on monday, i will post back and let everyone know. this problem has plagued me for 2 months now, it started by throwing O2 sensor codes then that stopped and multi misfire codes started. i tried everything to figure it out to no solution then i gave in and figured let the "GM experts" have a whirl with it.
Old 07-21-2006, 05:36 PM   #22
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by atwistd1
Having a similar problem and finally gave up and am taking it to my friend who is a GM mechanic. just on a quick look he seems to think that it is a bad coil. he said that this is not uncommon for a 4.3 to throw a multiple cylinder misfire code when the coil starts going. He is taking it in for me on monday, i will post back and let everyone know. this problem has plagued me for 2 months now, it started by throwing O2 sensor codes then that stopped and multi misfire codes started. i tried everything to figure it out to no solution then i gave in and figured let the "GM experts" have a whirl with it.

My coil was going bad but after I got it changed their really was not change. Mine still throws the codes O2 Heater sensor & Misfire. We checked all the sensors and they looked good but we are going to switch them around and see if it helps. I have had this problem since late April.
Old 07-21-2006, 09:24 PM   #23
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by scooter9715
My coil was going bad but after I got it changed their really was not change. Mine still throws the codes O2 Heater sensor & Misfire. We checked all the sensors and they looked good but we are going to switch them around and see if it helps. I have had this problem since late April.
switching them around wont tell you any thing all you will be doing is moving the problem from one place to another
the problem will still exist
Old 07-21-2006, 09:30 PM   #24
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Re: Rough idle / Multiple Cylinder Misfire

well i finaly made some progress.
i found that one of the hold down screws on the dist. cap was broken fixed that,
also found that there IS a fourth o2 sensor,
(F**K i thought i check carefully)
changed the fourth sensor and amazingly enough it appears to have solved my mystery.
i can't thank you guys enough for the help.
Old 07-22-2006, 12:28 AM   #25
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Re: Rough idle / Multiple Cylinder Misfire

I thought there was only 3?

wait. hmmm

one in the drivers side top of y pipe,
one in the pass. side top of y pipe,
One after the y pipe comes together b4 the cat.
& one after the cat?

I cant remember if the one where the y pipe comes together is for the pass side or a whole separate one.

Just checked, my '01 has 3.

One on drivers side. one on pass. side b4 the pre-cat,
one after the cat.

Where did u find a 4th?

Last edited by j894; 07-22-2006 at 12:42 AM.
Old 07-22-2006, 01:56 PM   #26
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Re: Rough idle / Multiple Cylinder Misfire

my brother is having the same problem (97 4.3l blazer). checked map, crank trigger, cam sensor, ignition module, maf sensor, ignition switch, plugs, coil. all ok. can't figure is out. really starting to frustrate me and my brother. has been doing it for about a week. backfires bad, rough idle, seams to miss below 1500 rpms. above that it runs better but not right. threw p0300. it has me really confused. have to get it fixed by Aug 4 because we are taking his truck to Havoc. distributer has some movement but not much. hope its not injector and if it is which nozzle. HELP!!!!!
Old 07-22-2006, 02:26 PM   #27
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Re: Rough idle / Multiple Cylinder Misfire

just checked dist gear. no signs of excessive wear. next is to check the spider
Old 07-22-2006, 02:49 PM   #28
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Re: Rough idle / Multiple Cylinder Misfire

ok quick question. how can it be the spider. it csefi. one injector per cylinder. if it is a random misfire then how can it be the injectors? how can the injectors randomly misfire? doesn't make sense. it would most likely be just one misfiring not all and not randomly. please explain.
Old 07-22-2006, 07:14 PM   #29
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Re: Rough idle / Multiple Cylinder Misfire

Just got back from the mechanic and he spent 6 hours checking and diagnosing on the computer he has at the shop.

here is what he found.
1. fuel filter extremly cloged.
helped but still bogs.
2. checked distributor for play. None cap and rotor ok also.

He thinks that possibly the spider assy cause cylinders 123 are all misfiring cylinders 45 sometimes mis but only randomly at WOT.

MAF cleaned and checked. seems ok but was puting out a high reading? when he squeezed the connector the reading went to normal but seemed to still run crappy.
He is not sure what is causing it cause it is random and seems to be at a certain rmp range or load placed on the motor then it leans way out. He wants me to see if i can "borrow" a new MAF to test and see if problem goes away if not then he thinks that the "poppets" in the spyder 1,2,3 are colgged from the filter being so bad. he gave me a real good fuel system cleaner to run thru it but said that he only gives it less than a 20% chance of working.

He also tested the throttle position sensor and said it seemed ok but could not entirely rule that out but was 95% sure it was ok.

On the way home i added the cleaner and 12 gals of super unleaded and we will see what it brings. it is now drivable but take offs are worse as is passing. sometimes even starting is hard now.

I hope it is not the poppets cause they are 100.00 each and he said if it's apart then might as welle do them all. total job would be about 900.00 MAF 350.00

He told me that the GM 60,000 mile check includes changing out the spyder assy and is an 1800.00 service

i will let ya know more as it happens.
Old 07-22-2006, 10:10 PM   #30
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Re: Rough idle / Multiple Cylinder Misfire

Cheaper here...

http://store.getgmparts.com/fj10453.html
Old 07-22-2006, 10:33 PM   #31
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Re: Rough idle / Multiple Cylinder Misfire

You can get a whole new OEM "spider" for around $350. MAF you can get new for $150 or less. Depends if you trade yours in for the core value.

Check ebay you can probably get both of those Things plus ALOT of extra parts for just over $100.

I dont think the 60,000 check includes changing the spiders, thats just stupid.
& Anyone who pays $1800.00 is getting burned
Old 07-22-2006, 10:34 PM   #32
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by Rhotpursuit

Think thats the wrong part. Looks like the 92-95 CPI spider
Old 07-23-2006, 12:32 AM   #33
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by j894
Think thats the wrong part. Looks like the 92-95 CPI spider

Could be...but it wouldn't hurt to check their prices.
Old 07-23-2006, 07:04 AM   #34
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by j894
You can get a whole new OEM "spider" for around $350. MAF you can get new for $150 or less. Depends if you trade yours in for the core value.

Check ebay you can probably get both of those Things plus ALOT of extra parts for just over $100.

I dont think the 60,000 check includes changing the spiders, thats just stupid.
& Anyone who pays $1800.00 is getting burned

Called the local GM dealer and asked what the 60,000 mile service included. I was told that it includes the spider replacement as well as a complete fuel system flush and filter change among the standard items checked. the cost here in NYC at the dealer a whopping $2200.00 plus tax 9%. when asked why the spider gets replaced, i was told that due to so many problems with the design and configuration it became standard to just replace it at the 60,000 mile service.. The service manager i spoke to made reference to some TSB to back this up. Iknow that my 25,000 mile check at the dealer was well over $750.00 for what they did, then i realized that it was a huge rip off at the dealer, but what can i say the truck was new, i was niaeve (sp?), and blinded by a new truck purchase.

Last edited by atwistd1; 07-23-2006 at 07:07 AM.
Old 07-23-2006, 07:07 AM   #35
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by j894
I thought there was only 3?

wait. hmmm

one in the drivers side top of y pipe,
one in the pass. side top of y pipe,
One after the y pipe comes together b4 the cat.
& one after the cat?

I cant remember if the one where the y pipe comes together is for the pass side or a whole separate one.

Just checked, my '01 has 3.

One on drivers side. one on pass. side b4 the pre-cat,
one after the cat.

Where did u find a 4th?
i thought the same thing
you were right above
1)one on drivers side cyl. bank before y

2)one on passenger side cyl. bank; before the y, tucked way up in, on the back side (this is the one i just found)

3)one about 12" away after the y but before the cat.

4)one after the cat

my simpathy goes out to anyone having this problem. its drove me f**kin insane for 6 mths or better.

Last edited by vespasoul; 07-23-2006 at 07:29 AM.
Old 07-23-2006, 07:13 AM   #36
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by low97s10
ok quick question. how can it be the spider. it csefi. one injector per cylinder. if it is a random misfire then how can it be the injectors? how can the injectors randomly misfire? doesn't make sense. it would most likely be just one misfiring not all and not randomly. please explain.
the eastist way to check injectors is look for a clean spot (which would indicate fuel dripping i.e. leaking injector
P0300 - Random/Multiple Cylinder Misfire Detected
sounds to me like youve got a spark plug wire in the wrong spot

Last edited by vespasoul; 07-23-2006 at 07:28 AM.
Old 07-23-2006, 01:38 PM   #37
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Re: Rough idle / Multiple Cylinder Misfire

can't be a wire in the wrong spot. he drove it to work just fine. ran a few errands and came out and started it and it started missing and idleing rough and running like complete crap. does it mostly below 1500rpms. backfires and just runs terrible. above that its a whole lot better but not great.
Old 07-23-2006, 03:36 PM   #38
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Re: Rough idle / Multiple Cylinder Misfire

just figured ours out and i feel really stupid. changed fuel filter and started putting everything back together and the contacts in the dist. cap were corroded from moisture. replaced it and it runs great. don't know why we didn't see it yesterday when we took it apart
Old 07-23-2006, 05:26 PM   #39
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by low97s10
just figured ours out and i feel really stupid. changed fuel filter and started putting everything back together and the contacts in the dist. cap were corroded from moisture. replaced it and it runs great. don't know why we didn't see it yesterday when we took it apart
sounds like a classic case of K.I.S.S.-
Keep It Simple Stupid
lol
Old 07-31-2006, 08:52 AM   #40
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Re: Rough idle / Multiple Cylinder Misfire

i got tired of trying to figure out what the darn problem is. took it to the chevy dealer for a computer diagnostic and hopefully get to what the problem is. depending on what the problem is i will fix it myself. hopefully i will get a call today with a diagnosis and i will keep ya's posted.
Old 07-31-2006, 06:47 PM   #41
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Re: Rough idle / Multiple Cylinder Misfire

Can't wait to here the update on your truck. I am hoping whatever your truck is having issues with my truck is too, my truck has since decided to lose horsepower. I get to a hill and it doesn't want to go and it takes the foot to the floor to get it up a hill and when I stop at a light she sits and shakes and has a bad exhaust smell.
Old 07-31-2006, 09:56 PM   #42
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Re: Rough idle / Multiple Cylinder Misfire

bit woot. got the diagnosis from the mechanic... the motor is blown. cylinders 1 and 3 have no compression. i supposedly need a new motor/engine. 6k new 3500 used. this is fantastic.. all this troubleshooting to find out it was something this bad? please give me feedback guys. i am so confused as if i should get a second opinion.
Old 07-31-2006, 11:27 PM   #43
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by ga76velez
bit woot. got the diagnosis from the mechanic... the motor is blown. cylinders 1 and 3 have no compression. i supposedly need a new motor/engine. 6k new 3500 used. this is fantastic.. all this troubleshooting to find out it was something this bad? please give me feedback guys. i am so confused as if i should get a second opinion.

A NEW LS1 crate motor is only $5400...hmmm
Old 08-01-2006, 02:11 AM   #44
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Re: Rough idle / Multiple Cylinder Misfire

Quote: Originally Posted by ga76velez
bit woot. got the diagnosis from the mechanic... the motor is blown. cylinders 1 and 3 have no compression. i supposedly need a new motor/engine. 6k new 3500 used. this is fantastic.. all this troubleshooting to find out it was something this bad? please give me feedback guys. i am so confused as if i should get a second opinion.
seems funny that it would have No compression at all.
Burned valve?

even so new 4.3s dont cost $6k, not even $3500.
)See them go off for well below $1k all the time.)
you can get a crate ls2 for that much. or used ls1 & tranny off ebay.

Last edited by j894; 08-01-2006 at 02:13 AM.
Old 08-01-2006, 05:04 AM   #45
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Re: Rough idle / Multiple Cylinder Misfire

I just had an engine swap done, and my 03' 4.3L is sitting in the garage, it has everything but a knock sensor and a fuel injection system, and it has 50K on it. If you pm me we can discuss it.
BUT GM are the cheapest bastards in the world, and ill go as far as to say it's a 50/50 chance if they're telling you the truth, they lie more than any other company I have ever heard of, so If i were you I would STRONGLY recommend having a compression test done somewhere else just to be sure. And the price they gave you for a motor is reason enough to assume they're lying, my local econo-lube said they could get a 50K mile 4.3L vortec for under 600$

If your curious and want my story, I had a bad misfire going on a while ago, so I had them check the codes which was supposed to be 100$, but turned out being 200$ after all their "extra labor", and they said it was a bad FI system and it "MUST BE REPLACED NOW IN THE SHOP FOR 2000$ NO GETTING AROUND IT" and I told them I would get a second opinion and they bitched at me for a while saying no other shop has the right parts to fix it and would rip me off, well i took it to econo-lube and they read the codes for free, and it turns out it was just 2 bad spark plugs, got a whole new set of them for 120$ installed and have never had a hickup again.

Last edited by Neeseius; 08-01-2006 at 05:17 AM.
Old 08-02-2006, 10:10 AM   #46
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Re: Rough idle / Multiple Cylinder Misfire

thanks for the insight. i was thinking about chevy said that those 2 valves are bent and thats what causing no compression. but they only did a computer diagnosis, they didnt put it apart or anything.. how would they know what the cause of the lost compression is? i just do not want to be scammed into replacing my engine if it is not necessary going to get the compression tested today by another mechanic to confirm chevy's diagnosis. ive spent so much money trying to figure out the cause of this problem. started as the P0300 code (random multiple cylinder misfire) with the rough idle, and loss of power. and look where i am now. trying to deal with the fact i might actually need a new engine. funny thing is, i read up on this and it states only 1 out of 10 cases of multiple cylinder misfires are due to dead/warped cylinders. every other cause is simple and easily fixable once diagnosed. sooo why the hell did i have to fall into that 1-10 worse cause statistic!! argg! i'll keep posting an update.
Old 08-02-2006, 11:14 AM   #47
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Re: Rough idle / Multiple Cylinder Misfire

they did a compression check on the cylinders. you dont need to take the engine apart. all you have to do is remove the spark plugs to do a compression test. most likely your short block is fine. remove the cylinder heads and have them rebuilt or to save you some money just have the bent valves replaced. from the looks of this thread and your lack of vehicle knowledge make sure you have someone else do the repair. this is the best case i have ever seen were someone throws parts at a vehicle hoping to fix it. if you live in florida i would be happy to fix your truck.
Old 08-03-2006, 08:47 AM   #48
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Re: Rough idle / Multiple Cylinder Misfire

haha. well maybe its because I am a girl! i am not that much vehicle literate. my fiancee does the fixing i just do the reading and research.

as per chevy, cylinders 1 and 3 have no compression at all. the mechanic stated the compression was tested wet and dry. its at another mechanic today to confirm the no compression diagnostic on those 2 cylinders. i will go from there.
Old 08-14-2006, 03:08 PM   #49
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Re: Rough idle / Multiple Cylinder Misfire

its confirmed i have two cylinders with no compression. second opinion advises to replace the engine like chevy said. oh well.. looking for engines now.. but they are so damn expensive. this really sucks.
Old 08-14-2006, 06:04 PM   #50
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Re: Rough idle / Multiple Cylinder Misfire

Cylinders 1 and 3 with no compression, its amazing how just about everyone on this forum are having the same exact problems. When my truck ran too lean for a couple seconds I blew the head gasket between those two cylinders as well. Compression was f**ked on both cylinders. Misfires, rough as hell idle. Had the cylinders machined, but I'm still getting a P0300 random misfire code and from what my scanner is telling me it is only cylinder 1 that is going crazy.

I've checked just about everything on here except the fuel injection system and distributor gear, nothing is wrong. No bad spark plug, no bad wires, MAF works fine. My truck is a 2001 and only has 14,000 miles on it, there shouldn't be much I have left to narrow down to. What the hell is with these damn trucks and there stupidass misfires? I'm going to do a compression test tomorrow, there better not be something wrong with that f**king piston or I'm going to be pissed. I wish I could take the truck to a Chevy dealer, but no way in hell are they going to look at it now that it's got a blower bolted on.

Last edited by DeViL; 08-14-2006 at 06:05 PM.
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