Idle Air Control Value Question

[bratfry]

Maxima 1999 Se

I have been battling the idle misfire problem for a couple months now. It comes and goes. I have done the O2 sensors, cleaned the throttle body, adjusted the throttle position switch, cleaned the Mass Air flow sensor and checked various other sensors. Sometime the car work great but the misfire always comes back. It also seems that the acceleration was not up to snuff and the transmission shift was funny. How is that for a technical description?

I finally got around to take off the Idle Air Control. I checked it out as per the manual, it was ok and even took it apart just to see how it worked. I did notice that the pintle valve was not uniform in appearance, looked different where it might be seating against the throttle body. Never seen a new one so I don’t know how they should look. Put it back on the car and the test drive showed the old misfire problems at idle and some misfire under hard acceleration.

Now for the heck of it, disconnected the connector to the Idle Air Control and went for test drive. No misfire on acceleration and no misfire on idle. Of course I got a Check engine light. The shift was better and the idle speed dropped faster to about 600-700. The idle speed at start and at a normal idle was very erratic prior to this test.

The question is, Is the Idle Air Control valve defective or is it not being controlled properly, maybe some other sensor isn’t giving the Engine Control Module the proper signals. I think that pintle tip looks very strange to me. Anyone got any ideas or any comments.

Thanks for any inputs...

Gary

[BP2K2Max]

your best bet is to just get a new IACV at autozone, they're like $3. if it fixes the problem, great, otherwise it's something else.

[bratfry]

$3, this thing is a steeper motor device like a computer disk drive. It has four winding phases to control it. I bet its well over $150, unless a person can just buy the value part. I don't know. I will look it up on autozone or Napa...

[BP2K2Max]

you're right. i'm thinking of the pcv valve. that'd be too easy.

[Nahkapohjola]

Originally Posted by bratfry

...and the transmission shift was funny. How is that for a technical description? Thanks for any inputs...

Cold engine uses TPS.
Tranny ctrl TCU uses TPS.
for TPS see: http://www.cardomain.com/memberpage/748507/6

for IACV: http://www.cardomain.com/memberpage/748507/4

Theyre very similar in any nissan, so maintenance procedures about the same. TPS resistance, (locations) varies between models, but in TPS linearity is the main issue...

[Nahkapohjola]

Originally Posted by bratfry

...and the transmission shift was funny. How is that for a technical description? Thanks for any inputs...

Cold engine uses TPS (after warmup O2 replaces TPS in engine ctrl)
Tranny ctrl TCU uses TPS always.
---> possibly worn TPS

for TPS see: http://www.cardomain.com/memberpage/748507/6
for IACV: http://www.cardomain.com/memberpage/748507/4

Theyre very similar in any nissan, so maintenance procedures about the same. TPS resistance, (locations) varies between models, but in TPS linearity is the main issue...

[bratfry]

Solution, at least for a while. I removed the Idle Air Control Value and used some 600 sandpaper and sanded the pintel ( I think that’s what its called) value end so it was somewhat uniform in color. The car has been running great ever since, great acceleration, nice idle, almost like new. So I guess I have to buy a new value. These things are not cheap, the best price I could find was about $240, thats a lot of beer money. I’m still suffering from Nissan parts sticker shock. My Ponitac IACV was $60. Must be the exchange rate of the yen. I am sure it is worth it.

Thanks for all the help, everyone.

Gary