rough idle problem

[punkbek3886]

my 4.0 L OHV is idling rough, i know of one vacuum leak but it will be fixed soon. but even if i push on this grommet to stop the leak it still seems to idle rough. can any of you help me?

 

[DonM]

Im told a leak will cause these problems, i would fix the leak and see if that helps!

Im curently looking into a vacuum leak! I have the same problem as you.


Don

 

[Bored_2wd]

pull out the O2 sensors. If they look like they've got black carbon on them, replace them. I just did it and the truck idles smoother and runs better.

 

[CDblazers]

I have the same problem with rough idle on my 99 sohc.. Idles rough then warms up to run fine i have tried a few things on this , cleaned maf , new plugs, cleaned the iac, and run injector through it. I too would like ideas on what next to try. any ideas if the o2 sensors can be cleaned or do they need to be replaced all together?

 

[TPLYNCH]

CD - Check your intake manifold O-Rings. The SOHC had a problem that caused your exact problems.... Search for O-Rings and see what comes up. There was an owner notification for the problem on the earlier SOHC engines, not sure if your '99 would have been included, but the problem may have carried over to yours.....

 

[punkbek3886]

where are the O2 sensors id have to clean?

 

[punkbek3886]

and also, how exactly can one clean the iac? ive been meaning to do it but dont know exactly what the job entails.

 

[TPLYNCH]

Search (see button at top of page) and ye shall find your answers....

 

[oceanworker]

Your 91 4.0 has only one O2 sensor. It is located on the exhaust pipe close to where the to headers come down ffrom the exhaust manifold and before your catalytic converter.
Pep Boys tried to tell me I had two and then gave me the wrong one. The wirng harness on the new one was too short to plug into the other end.
I went to NAPA and bought one made by Echlin, part # OS212.

I think the Bosch part is 13128 but I would check it on their website.

Changing mine cured my CEL problem and idling was better.

 

[punkbek3886]

by the way, my car idles fine when cold but starts to get rough when it warms up. my new intake which hasnt been finished yet takes in air from right next to the engine. i think that the idle gets rough when the intake starts taking in hot air. ill try to move it and see what happens. also, i did some diagnostics and i got a code which means that the coolant temp sensor is not registering. my temp gauge never really moves that much, could that cause the onboard computer to make the engine run rich or something?

 

[TPLYNCH]

Yes. The engine runs rich until it warms up. If the computer is getting a constant cold reading, it will continue to run it rich. This happens if your thermostat sticks open, or the temp sensor goes bad....

 

[punkbek3886]

thats sweet! my temp gauge is always reading cold and when doing diagnostics work i came across a code 167 which is coolant temp sensor out of range. ill replace it as soon as possible and see what it does. i bet it will fix it.