I bought it used from a seemingly anal dude who took extreemly good care of it. It has about 200,000 kilometers, burns (no / hardly any) oil and usually purrs like a kitten. Once in a while it starts idling very roughly. After quite a while it settles down again and is fine. Any ideas?
I've got an 93 3.3 and the same thing happens to me. I still don't know why. Cleaned the throttle position sensor, throttle body etc., everything people say to do, but it's still there. I would think if it's one of the above issues, it would always happen. Seems to me that something kicks it on and after a few seconds (30-45) it shuts off. No codes either. I'd be interested in the replies.
Nick
Just a thought, but does it may be the coolant temperature sensor incorrectly reporting a warm or hot engine when it is actually cold. These have not been reported here as common failures so I'd make sure I checked the more common things first: Throttle body/choke plate, Air Intake Servo, spark plug wires, spark plugs, fuel injectors, and vacuum hoses.
Bob
Let me offer this possibility. A faulty EGR system can cause rough idle. The EGR system allows exhaust gases to enter the intake manifold and mix with fresh air. This has the effect of diluting the intake gases into the cylinder and thus reducing the ignition temperature. Nitrous Oxides are thus reduced since they are produced at those high temperatures.
Diluting the intake gases isn't good all the time though, like during idle and during full throttle. This is because a diluted fuel mixture easily upsets engine performance at idle and reduces power during wide open throttle. So the EGR is not active during idle nor wide open throttle. If the EGR valve is stuck open (even intermittently) then idle will be rough and power is reduce during wide open throttle.
I believe there's a fault code associated with EGR malfunction so try to pull the codes using the ignition key method (on-off-on-off-on and watch the check engine lamp flash the codes) or go to AutoZone where's they'll scan codes for free.
There are other causes for this kind of temporary rough idle. One thing that is always temporary is engine temperature. Does the rough idle seem to coincide with cold engine temp, i.e., does it go away when engine temp reaches it's normal operating temp?
of it. It has about 200,000 kilometers, burns (no / hardly
very roughly. After quite a while it settles down again
I agree that a defective (stuck open) EGR could be the cause, but why would the rough idle smooth out after some period of time assuming it remains at idle and nothing else changes? The OP also did not report the SES light or any trouble codes. This is what led me to think it might be something related to the operating temperature.
Bob
It has happened after the engine is warmed up and I'm driving around town. Pulling up to a red light or a stop sign I'll notice it's idling roughly. Try to rev the engine a little doesn't help and it will stay that way until it's started the next day, then runs fine again. Like I said doesn't happen all the time, just maybe once a week. I looked up EGR and now that I know what it does, can anyone tell me where it might be located and what it looks like? Maybe if I swat it with a hammer it'll smarten up : )
I tried that and it flashed five times paused a second and flashed five more.
A google tells me this means 55 "End of error messages (If you get this only, no errors were found)" so nothing there, nice to know there are no problems.
Yep, 55 is "end of codes". At least there's no problems for which a code is set!
only, no errors were found)"
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