jcb wrote
innews: snipped-for-privacy@s13g2000prd.googlegroups.com:
>
>
>
>
> > > >> jcb wrote in news:a7733402-c7c7-4fa1-9e1c-
> >> snipped-for-privacy@21g2000hsj.googlegroups.com:
>
> >> > 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. >
> >> > Have a nice day
>
> >> I'm no expert....but
>
> >> I have a similar problem with my 03 SE-R SpecV.the idle increased to
> >> ~1500- 2000 rpm,drifted around,and soon enough,set the MIL light with
> >> an error code of P0507(too fast an idle speed).I had to go thru the
> >> idle set procedure,too.
> >> Eventually,the code cleared itself(MIL went out),it took quite a long
> >> time,though.
> >> my idle has been pretty stable recently.One thing that bothers me is
> >> the long time it takes for the RPMs to drop back after I get off the > >> gas pedal.
>
> >> there's a tech bulletin out on the power steering pressure switch
> >> going intermittent,causing idle problems.
> >> the switch normally tells the ECU to increase the idle when the
> >> steering is moved,to keep from stalling.
>
> >> this site is a big help;
formatting link
> >> you can download parts of the factory manual,one DL per 24hr period.
> >> They list all the bulletins for each Nissan model.
>
> >> --
> >> Jim Yanik
> >> jyanik
> >> at
> >> kua.net- Hide quoted text -
>
> >> - Show quoted text -
>
> > Thank you Jim for the quick reply...
> > I've done some research before posting this msg, so I am aware of the
> > website you mentioned. I am not sure my issue is the same as the PSP
> > switch, because while idling, if I turn the steering wheel, I saw the
> > idle speed changes (by dropping a bit and then jumping back to
> > ~1200rpm again), which means that the ECU receives the feedback from
> > the PSP switch and reacted accordingly. If the PSP switch is failed as
> > the bulletin described, then it should be always "ON" and there
> > shouldn't be any changes while tuning the steering wheel.
>
> In my case,I suspect the PSP switch is sticking intermittently.
>
> > I'm not really a mechanical savvy guy, so I'm not sure my analysis
> > makes sense or not.
> > I found another website saying that it could be "Idle Airflow
> > Controller" problem, but I haven't checked it out yet. I'll update the
> > group once I figured out what the real issue is...
>
> I don't think our model years(2002 and newer) have an idle air controller.I
> believe it's all controlled by the electronic throttle control.That's why
> you have to use a "procedure" to set the idle.
>
> Perhaps it's just the throttle body gummed up and needs cleaning.(SWAG) >
> Ther's a recall on the ECU for my 03,I'm not sure if it covers your year
> too,but it is something about stalling(IDLE PROB?) and involves a
> reprogramming of the ECU. I may get that reprogramming done.
>
> Maybe that would solve your problem,although I'd try cleaning the throttle > body first.
>
> --
> Jim Yanik
> jyanik
> at
> kua.net- Hide quoted text -
>
> - Show quoted text -
Hi Jim and folks, Just wanted to give you all an update... Unfortunately, I'm still not able to figure out what the problem was, but fortunately, the problem is gone ;-) This may be even more scary because who knows when it'll come back again. Anyway here is what I've done... I know it's essentially an air/fuel ratio problem, so started to trace done from the air intake end. I opened the air filter box and discovered that the air filter was kind of dirty and a bit of smoky too, so I replaced it with a new one. Then I tied up all connectors around the throttle area, as well as both O2 sensor connectors. I didn't expect any magic could happen by doing these, but after I drove the car to work, I performed the Idle Leaning Procedure one more time, while the car was warm. May be my persistent touched the heart of my car (I've done this learning procedure so many times since the problem occurred), or may be your great support created a miracle, the re-learning steps actually worked this time. The idle speed was set back to ~700rpm and still there since then. Now my car runs perfectly (very quiet, smooth and powerful), but sadly I don't know which specific thing that I've done fixed the problem. Anyway, life is back to normal... I may bother you guys later when the problem comes back. Have a nice day...