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hello i have a 93 accord with this werid ass problem that started about 2 weeks ago the car start great but when you drive it while its still cold it runs great but when it warms up it acts like its not getting any gas so i pull over leave it in drive the idles drops to around 400 in about 5 seconds the idle jumps up car runs like a new one but when you let it stay for more then 5 minutes this prosses starts over i get nom check engine light so i cant get the codes and the light does work my iac works i took my fast idle thermo value out cleaned it but still got the same problem so anyone knows whats going on here i also have cleaned out the iacv
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You mentioned the iac.. saying it works. these can get gunked up. some times you can clean them out with brake clean. another thing that controls idle speed is the coolant temp sensor. it is tied into the ecm and as the car warms up it lets the ecm know to adjust the idle. usually when this part fails the idle stays high all the time as the ecm still thinks the engine is cold. I suppose it could have the reverse effect if bad. I am sure eric will answer this post and will most likely have the answer.
Check the overall vacuum of the system at start up, and after warm-up. Also, ensure that the vacuum line going to the MAP (manifold absolute pressure) sensor is good. I would also check the PCV (positive crankcase ventilation) valve as well. Also look into the air filter compartment for engine oil. This would indicate a plugged PCV valve. Those are some initial thoughts (on my lunch break). Keep us posted.
IACV Cleaning
http://www.d-series.org/forums/diy-foru … aning.html
lots of good info here^^
I know you got an F series engine but cleaning the IACV is almost the same procedure if it is B,D,F,H series engines
You might also want to check for any vacuum leaks you might have as that could offset the mixture but to be honest it sounds like an electronic issue so I might check for codes even if you don’t have a light on just to be sure.
I’ve heard blocking the FITV off can solve a lot of idle issues.
In Japan they don’t even use the valve since it is used to help stabilize the idle and provide better running in cold climates.
What have you checked so far? I’m wondering if it might also be a good idea to check for an exhaust restriction as that is something else that could also cause an issue like that. You might try dropping the exhaust at the manifold and see if the problem changes or goes away, if it does then you may have a restricted exhaust.
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