Hello I'm new to these forums, but have read many articles on them about high idle problems due usually to throttle body cleaning. My problem is different. I bought a used 2003 Nissan Pathfinder SE with 82,000 miles on it almost a month ago and I love it, but I've had idle problems since I got it. When I took it on a test drive it was perfect, then I went to pick it up and drove about a half mile from the dealer (not a Nissan dealer) and the service engine soon light came on and it was idling around 500 rpms and would stall occasionally on restart unless I gave it some gas. I returned it to the dealer and they said the problem was the throttle body so they replaced it and the idle was no longer low but high around 1100 rpms. They did an idle air relearn 3 times now and it'll run fine at 750 rpms until it's run a bit then it's right back up to 1100 rpms. It takes about 2 days for the service engine soon light to come on, but inevitably it always does and gives me a p0507 idle control system idle higher than expected warning. All the hoses appear to be good so I don't think it's a vacuum leak, and I think the mechanic who's been working on it is stumped why it won't take the idle air relearn and stay. If anyone could possibly help or has had a similar problem any input would be greatly appreciated. Thank you.

From what I've read on this forum if all else fails it's the MAF. I'm not an expert but thats my guess.

That's crossed my mind as a potential cause, I took it to a Nissan dealer and they didn't have a solid answer, but said it was the computer and wanted to put a new ecu in. Then another Nissan dealer out near the dealer I bought it from said it was not the computer. I'm hoping that this mechanic my dealer is taking it to can track down the problem, I'll post what it is as soon as it's all figured out, but again any input anyone has would be helpful.

I tried to do a manual idle air relearn but it would not take. According to the Nissan dealer sometimes the idle air relearn done with the consult II doesn't take and it needs to be performed manually. I went through all the steps about a dozen times and my ses light stayed on. On the last time I went through the procedure I went all the way to the end and revved the engine a few times. I noticed something interesting when I let of the gas the idle would immediately come down to 1500 rpm, then it would drop to about 1250 rpm, and finally settle on 1100 rpm after each rev. Is this normal? Or is this indicative that something else may be wrong? Again any help would be greatly appreciated this high idle has been going on for a month now and it seems no one has the right answer to fix it.

I got the manual idle relearn to work but the idle never came down from 1100 rpm. Is there anyway I can test the MAF? I have a OBD II computer I can hook up to read codes and eliminate ses lights, but it's no consult II. Please advise.

Replace it and see if it makes a difference.

I had rough idle and I was able to diagnose it as the MAF. I found this out when I disconnected the MAF and the car had a much better idle. Replaced MAF and all rough idle/misfire is gone!

As I promised I would post what the eventual solution was to my high idle problems. It took months to resolve and wasn't the MAF. Finally a Nissan troubleshooter tracked it down as a couple of problems, first being the throttle body we got from Nissan was defective and I needed a new one, second there was an internal computer problem which contributed to the problem. They decided to reflash my computer to fix the issue and UPS lost my computer when they sent it back to the dealer. So the dealer had to get me a whole new computer. After the new throttle body and new computer went in the idle was perfect!

Another problem arose after about 48 hours. I got a p0172 engine running rich in bank 1. So I went back to the dealer and they got a new MAF as they figured that was the problem, it wasn't. My service engine soon light came back on 48 hours after the new MAF going in. So that is where I am now after 4 months of wrangling with this pathfinder. I'm leaning towards a faulty oxygen sensor, or a bad fuel regulator. My car is back at the dealer yet again and hopefully this will be resolved quickly.

Thank for posting your solution. I have 2003 Nissan Sentra SE-R 2.5L with 31000 miles. my idle rpm stay at around 1100 (this happens after I change the air filter, it has been two days but it never came down even I put back the old air filter.). I have done "idle relearn" few times but it doesn't help.

I also try to troubleshoot by what you found. Please correct me if I misunderstand.
1. it was computer problem so you have computer replaced.
2. it was throttle body issue, so you have this replaced.
3. However, in the end, it was MAF issue too, so you have MAF replace?

I am thinking to replace MAF since it is the cheapest component in the list. However, it is not the issue, then I will skip this.

thanks!

Bob

Hi Bob,

I thought I had it licked with the MAF cause the light stayed off for over a week them back on. After months of wrong diagnosis and a long list of new parts the dealer threw at it (O2 sensors, MAF, Injectors, Fuel trim line) they came back to the computer. Turns out it was a refurbished computer and it looked right but when taken apart it had the wrong board in it all along and was causing the engine to run rich. A new computer and the code was gone but my catalytic converter was fried from raw fuel being dumped down it. So the had to be replaced. Now I had a functional Pathfinder for a year with no problems. If you have a rich code check the O2, MAF, and Throttle body they are the most likely culprits. Y