"JM" <jmsn@[EMAIL PROTECTED]
> wrote in
news:478d3622$0$4077$9a566e8b@[EMAIL PROTECTED]
> "jcb" <mail.jun.l@[EMAIL PROTECTED]
> wrote in message
> news:a7733402-c7c7-4fa1-9e1c-980af78b5df4@[EMAIL PROTECTED]
> .
>> Hello experts,
>> I ran into a weird idle speed problem on my '02 Nissan Sentra SE-R
>> (QR25 engine, 5-speed M/T).
>> After about an hour of hwy driving (~60mph), I noticed that the idle
>> speed was up around 1200 rpm when I stopped at a traffic light.
>> Shortly after got home, while the car is still at normal operation
>> temperature, I performed the "Idle speed learning" procedure (I'm
>> sure I did everything correctly, because I've done that before);
>> however, at this time, instead of having the idle speed drops to
>> ~750rpm, during the learning stage, the engine sets the idle speed up
>> exactly at 1500rpm.
>> I've repeated the idle speed leaning steps few times, but every time,
>> it just sets to 1500rmp (btw, I read this number from the Scan tool
>> and there is no MIL light on. ECU doesn't sense any error)
>> I ran out of ideas. Any hints would be much appreciated.
>
> I had the same kind of problem with my '99 Altima. When I bought it
"pre-owned" or new?
> it idled close to 1000 rpm all the time, and it liked to want to rev
> up and hang there for a little bit whenever I came to a stop and
> pushed in the clutch. I couldn't adjust the throttle speed because
> the adjust screw was seized, but I eventually replaced it and was able
> to adjust the idle down, but I had to turn the screw all the way to
> get it close to 750rpm.
No idle speed screw on the 2000(Sentra) and newer QR25DE motors.It's all
done by the ECU.
> I still had the issue of it wanting to rev up
> when I came to a stop however.
>
> I also noticed that when in the idle adjust mode (with TPS
> disconnected) my revs were higher than with the TPS connected
> normally, as if the ECU was already compensating for the high idle but
> in adjust mode I was seeing the true scale of the problem.. Anyway I
> unfortunately didn't find the cause of the problem, but I thought I'd
> throw this (small) bit of info out there in case it helps at all.
> I checked for any codes, and didn't find any, tested the TPS with no
> problems, replaced the coolant temp sensor with no change, verified
> the MAF output as well as I could. I always wondered if I had some
> air in the cooling system that was affecting the coolant temp sensor,
> but never did disprove that one.
>
> I've seen a few posts of similar issues, mostly with Sentras for some
> reason, but I never saw a followup with what the solution was...
>
> Anyway I hope you find the problem, let us know if you do -- I sold
> the car to my dad so I can pass that on to him.
>
>
>
Perhaps a sticking idle air controller valve? (IACV)
It's on one end of the intake manifold,opposite from the throttle body.
my Haynes book says it can suffer from excess carbon deposits.
--
Jim Yanik
jyanik
at
kua.net
|
