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View Full Version : Very bad idle, and high emissions


sqd
03-02-2011, 12:46 AM
Neccessary info that you may need to know:
SR20 blacktop
850cc SARD injectors
Walbro fuel pump
PowerFC
Z32 MAF
+ a whole lot more, but I don't think any of it can cause this.

To make a long, long story a bit shorter:
Emissions read fine in May last year, then I recirculated the SSQV (because the car sometimes stalled when putting the clutch down when in higher rpms), then my exhaust manifold cracks, I think it's the manifold that causes my bad/high emissions, but I later find out it isn't. I remove the recirculation and get a custom built exhaust manifold & downpipe, emissions are OK for like a day or two. Then, the idle starts going bad, but just SOMETIMES. But even if the idle is ok, the emissions are still bad/too high.

I've replaced sparkplugs, O2 sensor, water temp sender, moved the MAF further away from the turbo (this made the car way more easy to drive in low rpm) and made sure that the exhaust has no leaks.

Now I've checked the fuel pressure and with a stock SR, it should be around 36 PSI, right? Well when I checked yesterday, my pressure was at 29 PSI.. So adjusted it to just over 36, and it started idling like this:

Video - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting (http://tinypic.com/player.php?v=5139fo&s=7)

Also, do you hear that strange, kind of squeaking sound? What is that? You can only hear it when it's idling rough like it does in the video. It comes from the head/intake somewhere, but it's kinda hard to locate.

And I THINK the reason why the bad idling has come and gone, is because when I was checking the fuel pressure, i noticed that the nut on top of the FPR was loose, so it could've adjusted itself, since the nut is supposed to prevent that..

Also, the car runs fine on boost/WOT.. But it feels a little sluggish, maybe due to the fact that the car is running rich, which is proven by the emissions test, they're all too high.

DreEzed
03-02-2011, 12:53 AM
Bump! Have a similar problem. Have you tried checking knock sensor or cleaning the IACV.

Does your car jerk at lower rpms in 1st or 2nd gear?

sqd
03-02-2011, 01:27 AM
No, I haven't checked the knock sensor, but I unplugged my IACV once, and it idled worse after that.. could it still be bad perhaps?

Well it used to, yeah - it became noticeably better when I moved my MAF further away from the turbo (I read that having it too close would create "turbulunce" in the intake pipe and cause the MAF to readings to become uneven and unstable).

sqd
03-07-2011, 09:33 AM
Bump! Have a similar problem. Have you tried checking knock sensor or cleaning the IACV.

Does your car jerk at lower rpms in 1st or 2nd gear?


So, have you gotten any further with your problem?

Got some more info:

Bought an AEM wideband sensor, shoved it into my tailpipe, AFR reads 11.6-11.7!

Took another video:
Video - TinyPic - Free Image Hosting, Photo Sharing & Video Hosting (http://tinypic.com/r/oiazic/7)

It idles fine, then i rev it, it "catches" the revs pretty late, then the revs starts bouncing up and down like it does at the end of that video. Then 2 minutes later, it idles fine again. Then, again, it can start bouncing/idling erratic again... And still that weird "squeaking" sound like in the video in my first post.

And also, tried adjusting the fuel pressure (vacuum disconnected), and the AFR won't get much better, even if i set it to super lean, it's still not better than say 13, but then the idle is even worse.

Also i disasembled the IACV, removed the spring and plunger - and the plunger can move freely within the IACV. Could it still be causing troubles? Also, unplugging the IACV kills the car immediately.