92 4.3 CPI s10 4x4 rough idle

[ksmolik]

Car starts and runs fine when engine is cold. after getting the engine temp. up and turning off engine and starting again. the idle speed is really rough. not so rough i think it is going to die, but not a smooth idle. when i accellerate it is smooth as ever and up to speed on highway it runs great. truck has 140K and has had CPI and nut kit replaced over 8,000 miles ago and i have checked the plugs, theyre fine....any input would be..greatly appreciated.

[ctesla]

kevin,
have you ever cleaned the Mass Air Flow sensor?
these items become sporadic in their signal sending sometimes due to heat and/or humidity. also, if many miles, the small "weather vane" type device that is in the air flow chamber can have small amounts of dust or debri built up upon it, causing a faulty signal, which would translate into poor or rough idle.

the correct way, is to actually take the MAF out, and carefully pull it apart to clean it; however, a quick and easy is to spray "sparingly" some air intake cleaner down the MAF across the sensor, and allow to air dry prior to closing up the air hose, then she how she idles.

when you changed out the CPI, did you leave stock, put in an aftermarket one, or did you change the air intake at all?
if this is the issue, pull the battery cable for a few minutes, or yank out the fuel inj/pump relay so as to rest the ECM to allow for a different air/fuel mixture flow value.

hope this helps,
chris
nrt racing

[crazycory1]

92 does not have a mass air flow sensor.

[ksmolik]

when i changed my fuel filter a few days ago.. i did unplug the fuel pump relay because i thought that relieved fule pressure, but i must have done it wrong because it still started with the relay unplugged. but i changed the fuel filter anyway. so what i mean is that i have unplugged the relay recently and same problem exists (intermittent rough idle at operating temp.) I will look into this MAF sensor, could someone also confirm that my 92 4.3 has a MAF sensor?? and to answer your question i did not do anything with the airflow system after replacing my CPI. So i have new fuel f., my air filter is good, plugs are good, should not be a CPI problem because it was replaced not long ago. and i also have run a bottle of chevron injector/valve cleaner about two tanks ago. also another question: what is a good cleaner to run in these engines tanks??and how often?? thank you for any input

[saywheresarny]

clean the egr valve or replace it