After getting the IMTV O ring's changed I still have what I consider a rough idle when cold. When car comes up to operating temp idle is perfect. Mech seems to think the coolant sensor could be bad at the low end. Would something like this affect the idle when cold. Plugs, coils, PCV ect are all new, MAF is clean. Any ideas where to start? T.I.A.
Coolant temp sensor failing=rough idle?
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joegr
Dedicated LVC Member
It could, but it's clear that he's just guessing. There's a lot of other things it could be too, so I don't think that just guessing and throwing parts at it is a good idea.
You can use a scan tool to monitor the temperature sensors. Before you start the engine in the morning, it should read about the same as the air temperature around your car. If it does, it's not your problem. There's absolutely no reason to guess about it.
You can use a scan tool to monitor the temperature sensors. Before you start the engine in the morning, it should read about the same as the air temperature around your car. If it does, it's not your problem. There's absolutely no reason to guess about it.
Hi Joe
Thank you for the reply. Do you know( and I'm sure you do ) how many temp sensors would be on the 2nd gen 3.0L. After searching on my E-Bay Repair man. disc I can only find a manifold temp and oil temp transducer. Does the manifold temp sensor effect the air/fuel mixture? My idle problem is only after the engine sits and reaches ambient temp(30-40F). Are these devices T.C's or R.T.D.'s. Do you know what these devices output are as far as span?(4-20ma/0-10vdc). Not being a car mech I always wondered what the standard was in the in the auto biz if there is one? T.I.A.
Thank you for the reply. Do you know( and I'm sure you do ) how many temp sensors would be on the 2nd gen 3.0L. After searching on my E-Bay Repair man. disc I can only find a manifold temp and oil temp transducer. Does the manifold temp sensor effect the air/fuel mixture? My idle problem is only after the engine sits and reaches ambient temp(30-40F). Are these devices T.C's or R.T.D.'s. Do you know what these devices output are as far as span?(4-20ma/0-10vdc). Not being a car mech I always wondered what the standard was in the in the auto biz if there is one? T.I.A.
joegr
Dedicated LVC Member
I haven't counted them, but there are a few. There's even a fuel temperature sensor.
I think you need to look at the live readings for fuel trim, temperature, and whatever else to see what might be going on. You could also hook up a vacuum gauge and see if anything shows that way. Be aware that this might not be a fault of the engine management when the engine is cold. It might be an actual engine problem.
I think you need to look at the live readings for fuel trim, temperature, and whatever else to see what might be going on. You could also hook up a vacuum gauge and see if anything shows that way. Be aware that this might not be a fault of the engine management when the engine is cold. It might be an actual engine problem.
are you running 91+ octane?
run a bottle of lucas (or whatever kind of injector cleaner you prefer) thru it and it will disappear so long as you continue to use 91+ octane and recalibrate the idle/fuel sensors.
did you clean your IAC valve?
i think i need to clean mine, but i cant find anything on cleaning the gen ii, which looks a bit more complicated then the gen i. lots more screws/bolts poking out of that thing. mine doesnt idle rough tho. got a little whistle occasionally when its cold
run a bottle of lucas (or whatever kind of injector cleaner you prefer) thru it and it will disappear so long as you continue to use 91+ octane and recalibrate the idle/fuel sensors.
did you clean your IAC valve?
i think i need to clean mine, but i cant find anything on cleaning the gen ii, which looks a bit more complicated then the gen i. lots more screws/bolts poking out of that thing. mine doesnt idle rough tho. got a little whistle occasionally when its cold