My 2002 has been giving me trouble over the past month, I'll list what has been done to get a full picture:

1. MAF died on me merging onto the highway, was in limp mode unsafe to drive. Had it towed home, couldn't believe the price difference between 2k1 and 2k2 MAF's. Found thread on using 2k1 MAF with thermistor swap, worked perfectly for me. Car ran great for 2 weeks.

2. Alternator died draining battery to the point that the car did not want to stay running (on the highway yet again). Big $$ tow 40 miles back to my house. Consider tackling job myself but fed up with car so I charge battery enough to drive it to local garage for ALT replacement. $450 later I have a functioning alternator.

Yesterday was the first day I drove the car for an extended period to work, I noticed in the afternoon that the idle would drop below what I would consider normal...almost to the point that it wanted to stall but would catch itself. I noticed this the most when in traffic or coming to a stop where the clutch would be in before completely stopping, the idle would drop to 500rpms or so then come back up in the 575-650 range. The car runs great otherwise, I've been unsuccessful with performing the idle relearn the couple times I tried it but from everything I have seen in searching the idle relearn is done for a high idle not a low one? It will idle normally after it dips low and surges a bit, it also seemed like it took about 45-50 minutes of driving this morning before I noticed the first 500rpm surge. I had no check engine light yesterday when I first noticed the problem. Could this just be a failing sensor or do I need to just get the timing down right on the relearn? Any help would be appreciated.

 

Seems like you need to do the Idle re-learn as well as the TPS.

 

Some codes will not pop a check engine light until it has been recorded for a certain amount of miles. This is called a pending code and may be worth pluggin in a scan tool.

 

It seems like the part I'd like to try replacing is the idle air control valve...problem is I cannot seem to find this part by itself (I do see it on rockauto included with a new throttle body). Somebody please tell me I don't need to buy a new throttle body if I do infact need to replace the IACV?

 

Good point, I do have a check engine light on today but this has been the normal routine for this car over the past 2 years having to do with an EVAP code, I will check the codes when I get home for good measure.

 

The iacv is a part of the throttle body on the vq35 motors.

 

Terrific, replacing parts on this thing just keeps getting more and more frustrating. Hopefully I can get the relearn to stick later on today.

 

im in ct. I do have an extra throttle body from my old engine.

 

^^ I'll keep that in mind, thank you.

I just went for a ride at lunchtime to try the idle re-learn again, this time I got it to flash like it's supposed to. First start up after that it died immediately, then started right back up and idled a bit rough for a minute or two. It seems to be returning to 600-625 idle but I am not 100% confident that the problem is fixed.

I had a thought about the new belts that were installed...if the tensioner was too tight could it cause a surge when returning to idle?

 

Well it seemed to do better on the ride home compared to yesterday, however there wasn't as much stop & go today. I did notice 1 500rpm surge when coming to a stop though, checked the SES codes and it was only a P0455 EVAP leak as I've had for a few years now...any other ideas?

 

Was this 2000 2001 maf from nissan? If not that can be your issue.

 

The MAF is a brand new 00-01 that I got from DaveB. and then swapped the thermistor, it ran excellent for 2 weeks no idle surge problems until after the alternator died and was replaced.

 

other than the idle air relearn there is an ecu reset thing. iirc it send your ecu into a relearn maps mode. Other than that Id say to get the evap crap fixed cuz u never know.

 

It's not the EVAP, like I said I've had this code consistently on and off for the last 2+ years.

Solution might be a for sale sign.