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Discussion Starter #1
My truck idles rough, possibly just too slow, whether in gear or not or a/c running or not. If I squeeze the throttle to 700 rpm, it's smooth as silk, but drops back to 600 or even 500 rpm without me giving it some throttle and I think it's going to stall. I have seen this question all over the internet, but no answers.

The Chev dealership cleaned the throttle body, the fuel injection system and installed a new fuel filter, but same problem. I run good quality fuel. I get the feeling they will charge me hundreds "trying" to fix what is obviously a wide spread problem where they should know the answer already. Next, they suggest reprogramming...another hundred.

Can I simply increase the idle setting to 700 rpm? How? What rpm is the 4.3L supposed to idle at? I guess it's time to buy a manual, but in the meantime...

Any help is appreciated!
 

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Over on the ZR2 site,some guys have posted with the same problem.Worst case scenario; distributor gear -least case; faulty ground.
If it is the gear that is still a relatively inexpensive fix.$60 for the AC Delco gear from advanced auto and I believe one of the guys said the dealer charged like $150 to change it.First check all the grounds:headlights,negative battery cable and engine block grounds.I removed mine and used a dremel to "rescratch" the metal around the holes for the grounds and wire wheeled the screws.A few of mine had some corrosion which can cause problems.There is also a guy on the site that sells new battery cable kits for the S-10s.These are very nice and those that have bought them say that their ZR2 runs better,better consistent idle and brighter headlights.I will be doing this mod when I get the money.I think they run like $80-85 +shipping but well worth it.Hope this helps some. www.zr2usa.com
 

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disconnect both battery cables and touch them together for about 20 minutes. this will discharge the capacitors in the ecms and make them relearn all parimeters. It may be as simple as that. Sometimes these car computers need to be brain deaded.
 

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Discussion Starter #5
Do you have a K&N air filter? Could be a dirty MAF sensor. Check to be sure that the MAF is plugged in tight.
Ok, I admit to not knowing what or where an MAF sensor is. No, I don't have a K&N, just the stock filter set up and it is clean.
 

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disconnect both battery cables and touch them together for about 20 minutes. this will discharge the capacitors in the ecms and make them relearn all parimeters. It may be as simple as that. Sometimes these car computers need to be brain deaded.
Are you serious? On one hand this makes sense, on the other...
 

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Discussion Starter #7
Over on the ZR2 site,some guys have posted with the same problem.Worst case scenario; distributor gear -least case; faulty ground.
If it is the gear that is still a relatively inexpensive fix.$60 for the AC Delco gear from advanced auto and I believe one of the guys said the dealer charged like $150 to change it.First check all the grounds:headlights,negative battery cable and engine block grounds.I removed mine and used a dremel to "rescratch" the metal around the holes for the grounds and wire wheeled the screws.A few of mine had some corrosion which can cause problems.There is also a guy on the site that sells new battery cable kits for the S-10s.These are very nice and those that have bought them say that their ZR2 runs better,better consistent idle and brighter headlights.I will be doing this mod when I get the money.I think they run like $80-85 +shipping but well worth it.Hope this helps some. www.zr2usa.com
Thanks, I will check all the electrical connections I can find.
 

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that is actuatly a BMW repair. the ecm can get confused in vehicles just like your home computer. I do this about once a yr to my vehicles and i have had no major problems.

your truck may/may not have a bus system. i am unsure if gm put them in the s-trucks or not. when you brain dead teh vehicle you brain dead the bus systems and it clears all the false info that is traveling on them.

BTW a bus system is 2-wires twisted together in a pair that transfers info from one control module to the other. It is basically like a 2 lane highway. They use bus systems to keep the wire harness to a minimum. I hope I have not confused you even more.
 

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Ok, I admit to not knowing what or where an MAF sensor is. No, I don't have a K&N, just the stock filter set up and it is clean.
As the air leaves the air cleaner, it goes through an aluminum section that has an electrical plug attached. This is the Mass Air Flow Sensor. If you take off the air filter rubber adapter on the MAF you will notice that there is an aluminum plate drilled with many holes in a "honeycomb" fashion. This plate reduces the turbulence of the air entering the MAF and increases the accuracy of the instruments readings.

The MAF itself is 3 wires stretched across the diameter of the MAF housing and it is these wires that sense the airflow. If the wires become dirty, it can cause erratic readings and rough operation of the motor. The K& N filters use oil on the surface of the filter media, and this oil can come off and get on the MAF causing erratic readings.

It is a good idea to clean the MAF sensor wires with a good spray solvent. Most auto parts stores carry a solvent especially for this purpose.
 

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Over on the ZR2 site,some guys have posted with the same problem.Worst case scenario; distributor gear -least case; faulty ground.
If it is the gear that is still a relatively inexpensive fix.$60 for the AC Delco gear from advanced auto and I believe one of the guys said the dealer charged like $150 to change it.First check all the grounds:headlights,negative battery cable and engine block grounds.I removed mine and used a dremel to "rescratch" the metal around the holes for the grounds and wire wheeled the screws.A few of mine had some corrosion which can cause problems.There is also a guy on the site that sells new battery cable kits for the S-10s.These are very nice and those that have bought them say that their ZR2 runs better,better consistent idle and brighter headlights.I will be doing this mod when I get the money...
If you want to test the ground straps, just use a set of jumper cables. Connect one to the block and one to the frame while the engine is idling. Then connect one to the neg battery terminal to the block.
If the idle smooths out....
 

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Discussion Starter #11
As the air leaves the air cleaner, it goes through an aluminum section that has an electrical plug attached. This is the Mass Air Flow Sensor. If you take off the air filter rubber adapter on the MAF you will notice that there is an aluminum plate drilled with many holes in a "honeycomb" fashion. This plate reduces the turbulence of the air entering the MAF and increases the accuracy of the instruments readings.

The MAF itself is 3 wires stretched across the diameter of the MAF housing and it is these wires that sense the airflow. If the wires become dirty, it can cause erratic readings and rough operation of the motor. The K& N filters use oil on the surface of the filter media, and this oil can come off and get on the MAF causing erratic readings.

It is a good idea to clean the MAF sensor wires with a good spray solvent. Most auto parts stores carry a solvent especially for this purpose.
Thanks, I will clean the MAF.
 

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Discussion Starter #12
If you want to test the ground straps, just use a set of jumper cables. Connect one to the block and one to the frame while the engine is idling. Then connect one to the neg battery terminal to the block.
If the idle smooths out....
Easy! I'll try it. Thanks.
 

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Discussion Starter #13
that is actuatly a BMW repair. the ecm can get confused in vehicles just like your home computer. I do this about once a yr to my vehicles and i have had no major problems.

your truck may/may not have a bus system. i am unsure if gm put them in the s-trucks or not. when you brain dead teh vehicle you brain dead the bus systems and it clears all the false info that is traveling on them.

BTW a bus system is 2-wires twisted together in a pair that transfers info from one control module to the other. It is basically like a 2 lane highway. They use bus systems to keep the wire harness to a minimum. I hope I have not confused you even more.
Computers...Garbage in, garbage out. A cleaning up is in order. Thanks.
 

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i bet you got some dry-rotted vacuum lines sucking in unmetered air. no check engine light? i would go to advance auto or any other parts store and have it read either way... if you bought the truck used, someone could have just taken the bulb out so they could sell it. i know ive done that a few times lol.
 

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Did you ever fix the problem....I am having the same problem...cleaned the MAF but that is as far as I have went. I also tried unpluggin the MAF and driving it but I idled just the same........
 
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