Rough Idle

[Alexxn 00 Si]

Hello all,

I have a 2000 Chevy Blazer 4x4 LT with the 4.3L Vortec engine. It has @ 60K and has been well maintained. I am having a slightly rough / shaky idle and changed the air, gas, pcv and also cleaned out the throttle body butterfly and also added some GM fuel injector cleaner. Is there an idle solenoid that needs to be cleaned ? Any other ideas ?

Thanks

[flytem3]

I had a similar problem and replaced the plugs (major pain the ass as chevy decided to put the center plug on the passenger side directly behind the steering column. I broke 2 plugs off before getting the third in...) and wires and it cleared it right up...at least for a while. See my post from today..

Greg

[Alexxn 00 Si]

Originally Posted by flytem3

I had a similar problem and replaced the plugs (major pain the ass as chevy decided to put the center plug on the passenger side directly behind the steering column. I broke 2 plugs off before getting the third in...) and wires and it cleared it right up...at least for a while. See my post from today..

Greg

Thanks but.......I believe this year has platinum plugs which are good for 100,000 miles....I could be wrong though.......

[cobra1]

Originally Posted by Alexxn 00 Si

Thanks but.......I believe this year has platinum plugs which are good for 100,000 miles....I could be wrong though.......

first off remove each plug wire (putting it back on before removing the next) one at a time, so that their easy to remove after starting the engine. then using welding gloves, or a plug wire puller or something insulated, start the engine, and again remove a plug wire and listen for a change in engine speed, put it back on and repeat for the remaining 5. if you pull one off and there is no change, then you have the affected cylinder. check for burned plug wire, improperly gapped/faulty plug, etc. might also be the ignition module....

if all that is ok, move on to the fuel system. connect a fuel pressure gauge, with the key on and engine not running, you should have 55-61 psi. if so, start engine and check again, with engine running it should decrease by 3-10 psi.

if that is ok, look for vacuum leaks. all that should keep ya busy.

60,000 is the about when my 95 S-10 burned a plug wire, but it would only miss going uphill.

[Alexxn 00 Si]

Anyone else know anything about an idle solenoid or what could be causing this ??

[cobra1]

Originally Posted by Alexxn 00 Si

Anyone else know anything about an idle solenoid or what could be causing this ??

idle air control valve (IAC), controls the idle speed. a Haynes book gives the proper pin diagram for checking these with an ohm meter, but i seriously doubt this is your problem.

also, if the IAC is disconnected for testing, the PCM will have to relearn its idle mode.

[Alexxn 00 Si]

Originally Posted by cobra1

idle air control valve (IAC), controls the idle speed. a Haynes book gives the proper pin diagram for checking these with an ohm meter, but i seriously doubt this is your problem.

also, if the IAC is disconnected for testing, the PCM will have to relearn its idle mode.

Ohhhh OK.....so if everything else that you suggested above checks out then thats about it ? I know the 4.3 isn't supposed to be smooth as glass but should it be pretty smooth ? Maybe I am expecting too much out of it......

[cobra1]

it has an internal balance shaft, and therefore should idle smooth. least both mine do, and the 95 S-10 has 176,000 miles on it.

you shouldnt really notice any engine movement while running. heck, when the 95 was new and stock, you couldnt tell if it was running, it was so smooth and quiet..... so much so i tried to start it a handful of times when it was already running.