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P0305 misfire cylinder 5

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Old 09-02-2006, 03:28 AM   #1
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P0305 misfire cylinder 5

Today all of a sudden while driving my truck uphill on a bridge it started sputtering, dying out, and throwing the SES light. It misses slightly at idle with no load, but when I turn on the A/C it almost dies. I also have to give it a abnormal amount of gas to get moving. I took it to autozone pulled the code and it said misfire cylinder 5. So I thought maybe I have a bad plug or dirt in the plug so I replaced it same problem. I checked the rotor cap and rotor both are fine, and I replaced the wire on that cylinder all with no luck. I tried cleaning the MAF sensor as it had some buildup on it no improvements.

Now here is what was strange to me, I accidently left the MAF unplugged after cleaning it and took it down the road, but it didn't seem to run much worse than with it plugged in. So I am wondering is it possible my MAF is bad? Is there anyway to test the MAF with a multimeter or something so that I know it is working properly, or can someone come up with some other idea as to what is going on with my truck?

Is it possible that it is the fuel filter as I can't remember if I changed it or not since I got the truck and I am at 110K miles? I was thinking fuel filter until I had the code pulled, but it runs almost like the whole engine is starved for fuel. I don't know its really late and I am to frustrated with this to sleep.

Specs are as follows:
2000 Chevy S10
L35 262ci vin W
Almost 110K miles

Mods:
Throttle body spacer
Flowmaster exhuast
!CAT!
02 sensor simulator

Any ideas are greatly appreciated as I am getting stumped, and I don't want to buy more un-needed non-returnable parts.
Old 09-02-2006, 04:36 PM   #2
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Re: P0305 misfire cylinder 5

Just a update I replaced the fuel filter today, and I am still getting the same problem. I also pulled the plug wire from the supposed misfiring 5 cylinder and it ran worse so I don't think it is really misfiring . Idle to about 1800 RPM with no ac runs fine but any RPM's above that or if I turn the ac on I get a misfire like situation. I took the breather assembly off and started the truck and used carb cleaner to keep it going and I didn't have the problem. I am down to just a few things my friends car did the same thing my truck is doing when the MAF went bad. So it is either that or fuel pressure, or possibly a plugged poppet nozzle?

Anyone else with some ideas?

Is there any way to test the MAF without a scantool? I can get a scantool on Tuesday but I need my truck before then. Anyone????
Old 09-02-2006, 06:38 PM   #3
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Re: P0305 misfire cylinder 5

same problem i get, i think this is the cause of our problem, http://www.s10forum.com/forum/f107/if-your-having-a-mystery-running-like-crap-problem-268309/
Old 09-05-2006, 01:47 AM   #4
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Re: P0305 misfire cylinder 5

the computer throws a misfire code if it is missing more than 5% of the power strokes

I'd change the MAF before i spend $300 bucks on a updated fuel injector
Old 09-05-2006, 10:59 AM   #5
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Re: P0305 misfire cylinder 5

If you want to throw a few sensors at it For a cheap solution there is a guy on ebay selling them do a search for 4.3 sensor and look for a guy named ragged's auto parts. I bought the set he sells it included the tps, iac, air diverter, ignition module, and the MAP for $50. My truck is a 92 CPI.
Old 09-05-2006, 02:56 PM   #6
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Re: P0305 misfire cylinder 5

Thanks for all the help! I took the truck in today, but they were to busy in a meeting to scan it. I am going to try to borrow a friends MAF and see what happens, but I only know one person with a MAF style 4.3 S truck and I don't know if he will let me borrow it. If he doesn't they said that they will have time to scan my truck tomorrow, and I got quoted $105 for a new one plus core. I don't think that is to bad. I do notice that my truck does not run any worse with the MAF unplugged so I am almost certain that it is the culprit of my problems. I will post back when I know a little more! Thanks again!
Old 09-07-2006, 11:43 PM   #7
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Re: P0305 misfire cylinder 5

Okay well took it and hooked it up to the scantool, and after clearing the 521,000 entries that were in the computer we ran the truck for 5 minutes. In that 5 minutes I had over 1000 misfires on cylinder 5, and 600 on cylinder 4. The mechanic has seen this problem before and is also blaming the fuel injection system. I have raised hell at Chevrolet about this, but none of the local dealers seem like they want to do much about it even though I have a case number and all with chevy. I don't think much is going to come from the call, and I don't think that I am going to take it back as I have to many mods that would be to hard to reverse as I don't have many of the stock parts to swap back in, and I know how GM is about mods . So hopefully I am going to look at the poppet nozzles in the moring and see if anything is going on with them. There is a shop that works on fuel injection systems in town, and I might see if they can clean them and get me by long enough to get more money up for a new vehicle or unitl I can shell out the money to fix it right. I will keep everyone posted on what I find.
Old 09-07-2006, 11:53 PM   #8
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Re: P0305 misfire cylinder 5

Yeah to be honest it sounds like the poppet injector i had the same problem on a 97.Besides if you unplug the MAF and it runs the same the PCM will make fuel and spark decisions fom the MAP and TPS and O2's with a ses light on with a justified fuel and spark map from those values.And okie way of telling what sensor is bad is take it out of the loop and unplug it the pcm will make adjustments for it.
Old 09-21-2006, 05:54 PM   #9
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Re: P0305 misfire cylinder 5

Okay MFI parts came in and they are installed, but I am still having the same issue as posted before except I am out $250. I think when they scanned my truck that they didn't look at the fuel pressure reading. It is not throwing a code, but when I pushed in the fuel pressure relief valve it just dripped some fuel out of the lines it didn't spray at all. I am getting a fuel pressure tester tomorrow to see what is up with the dumb thing. Any one else with ideas?
Old 09-23-2006, 02:01 PM   #10
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Re: P0305 misfire cylinder 5

Okay fuel pump goes to 60 for a second when I turn the truck on or off, but at idle stays around 45-50psi is this normal? When I rev the truck it kicks up to about 55 on the gauge. Anyone know if this is normal operation?
Old 03-11-2007, 10:57 PM   #11
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Re: P0305 misfire cylinder 5

yes
Old 03-11-2007, 11:02 PM   #12
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Re: P0305 misfire cylinder 5

i have same problem too. im cleaning the maf right now, its filthy. i istalled a K&N filter a year ago so im thinkin thats part of the buidup problem on the maf.

So jason let me get this straight, you replaced the injector assembly and no change at all? if so thats good to know cuz that was gonna be my next option. im also going to check the vacuum lines and pressure as well. peace
Old 03-12-2007, 12:23 AM   #13
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Re: P0305 misfire cylinder 5

The misfire codes,especially when giving the exact cylinder (ex. 5) are set when the Crank & cam position sensor determine the crank is slowing down (or not speeding up) during the power stroke, when it should be firing. So, just about anything that would slow it down/ not let it fire, might cause that code. Some people have had the problem with the injector & that was the cause of it. (kinda hard to run right if one of the injectors is messed up & and not delivering enough fuel to drive the piston) I remember someone on here ended up having a burned valve & thats why it was setting a misfire code. There is no one solution, there are many things that could cause the code. Due a tuneup lately?
Old 03-12-2007, 07:58 PM   #14
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Re: P0305 misfire cylinder 5

im doin it right now, new wires cap rotor plugs, cant wait to see the plugs
Old 03-12-2007, 10:50 PM   #15
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Re: P0305 misfire cylinder 5

I just did conversion several weeks ago.
Here are the pictures: GM FI Spider upgrade pictures from trucks photos on webshots
Best $210.00 I've spent so far on parts!! The Jimmy runs great!
Here are the part numbers for the spider and gaskets.
GM PART # 17113215
MFI spider #12568332
GM Parts Direct: Your direct source for Genuine GM Parts

The kit is only two gaskets. One for the throttle body and the other for the uppermanifold. You don't need orings for the fuel lines. The orings are inserted into the new spider. Just push down the fuel lines into the spider and bolt down. Order the GM spider from GM parts direct. Pricey shipping but worth it. I spent <$210 for both part numbers.

You need these parts too.
1 can of throttle body cleaner
1 can of carb cleaner for the upper manifold
1 can for the air intake sensor
1 10mm deep socket for the manifold gaskets
1 5.5mm socket for one of the TB bolts
1 small tube of thread lock or sealer. I use the small blue tube type.
A small hex set to remove the air idle valve.
Clean the EGR valve and idle air valve too.
I recommend changing the map and throttle posistion sensors.

Key notes:
1. Disconnect the battery
2. Releave the fuel pressure
3. Pull and remove the harness wire connections from the air intake sensor all the way to the sensor on the passenger side of the intake.
4. Layout all the bolts and parts on a flat surface so you know where to put them back.
5. You can bend the fuel lines back far enough to remove the intake just be careful. Otherwise to remove the fuel lines, you may need the wrenchs that can go on a socket.
6. Route the spider fuel lines just like the originals. All should run forward from the FI spider bracket. You should only loop back the #5 and #6 lines.
7. Use the carb cleaner to remove the junk from the intake.
8. Don't drop anything down the runners.
9. Once the new lines go into the intake they won't come out!!! Snap in the new lines once you are sure that you won't need to remove them.
10. Use a dab of grease on the upper portion of the spider that slides up into the manifold. Use a dab of grease on manifold opening that goes over the spider. This will save you the trouble of having to push down hard on the intake to seat it.
11. Clean the TB really good. Remove the plastic weird looking thing on the TB opening plate. This will increase air flow.
12. GM did a good job on the gasket design. Just tighten the bolts to a snug. You can go back later and tighten them a little after the engine has warmed up and coold a few times. However you don't need to do this if you use the thread sealer.
13. Bolt down everything and connect the hoses.
14. Before installing the air intake hose, check for fuel leaks. Connect the battery and turn the key to ignition. Let the pump prime the line. I did several times so the pressure will buildup. If you don't see any fuel leaks, install the air intake hose, misc hoses, reconnect the sensors and wiring harness.
15. Start it up and check for fuel leaks!! Let it idle up to normal operating temperature before going for a test drive.

This is my first time doing a FI injection job. It was fairly easy. Just take your time and be careful. My Jimmy runs like a champ. I bet even my fuel milage will be better. I was down to 14 MPGin the city! I can already tell it's back to up the 16-17 mark and maybe more. Throttle response is awsome!! Idle is smooth. You'll like the conversion.
Old 03-17-2007, 10:46 PM   #16
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Re: P0305 misfire cylinder 5

i may do this conversion also thnx
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