Okay so first the SES light came on and the code read P0158 (rear bank o2 sensor). Reset the code but light came back again, this time code P0160 (different 02 sensor.) Car stalled a few times and was generally sluggish. Took it to the mechanic, he replaced an 02 sensor but the light came back again. He claimed that he replaced the wrong sensor and the code was being given because of a problem in the TB. He then cleaned the TB and reset the light. Car ran fine for about 50 miles. Parked for several hours and after restarting it, it revved up to 25000 rpm and stayed there for a couple min (60 deg weather so it wasn't cold out). I floored the accelerator and then it dropped to 1500rpms and ever since has been fluctuating between 1500-2000rpms at idle. The mechanic claimed that it may have been the idle control valve but replacing it didn't fix the problem. Car is now at the mechanic and supposedly he's took it to another mechanic to reprogram the ECU but last time we spoke the problem was still there. Anyone have any idea what the problem could be??? Could he have messed up the TB when he "cleaned" it??? Thanks...

 

now, he's saying the problem is with the idle control switch. Putting in the new switch didn't fix the problem so he checked the computer to make sure power was going to the switch. Power is going there, and everything seems to be working fine, but for some reason the switch itself is not working. So if the power is going there, and the switch is brand new, what can be wrong... Well now the car is at the shop and needs to go to the dealer to have the computer reprogrammed. The mechanic says this should be the problem. Any input/ideas?

 

Sounds to me like engine misfire. A bad coilpack...maybe even bad injectors could be your problem. How many miles do you have? Have you replaced the coils yet? The VQ30 was notorious for bad coils. Is the car running rough during idle/driving?

 

I thought it might be bad engine coils. It's not the injectors, they were all checked. The car has about 87k on it. It's not really running rough at all, it just doesn't idle smoothly. RPMs just go up and down. Other than that it drives fine.

 

If the injectors are alright, then I would begin testing the coils. I am not exactly sure how you do it but I know that if you search on this site there are fourms that describe it pretty well.

 

if the coils were bad, wouldnt the car have a rough idle/ride?

 

This is NOT a coil or injector issue. Ask your mech. if he is working to the Factory Service Manual? We've already seen enough blown ECM power transistors/circuits related to the the idle control on the Gen. 5s. Not sure what "reprogramming" your mech. thinks will cure this idle problem. It won't. There are only two components on the TB. The Idle Air Control Valve and the Throttle Position Sensor that also incorporates a Closed Position Switch and a wide open throttle switch. When you replace either one of these components there are several procedures/adjustments that have to be done. All of these procedures are CRITICAL. Has he done them? Yes, cleaning the TB has been known to cause problems.

 

He obviosuly did not do them...the car is at the dealer now and they tell me it need a new ECU and MAF!!! $1600!!! The MAF and ECU were completely find until the mechanic started playing around with the car. It basically disappeared for a few days to his friends shop while they were trying to fix the problem. It is pretty clear that he turned a small problem into a very big one by messing with the TB. Now my car is out for 2-3 days while they are gettin the parts...

 

ok so I did some research http://forums.maxima.org/showthread....highlight=IACV and I think this thread pretty much sums up my problem.

The mechanic cleaned the TB and must have done it incorrectly so now I'm getting the high/fluctuating idle. So now either the TB has to be replaced or the ECM? I need some evidence that the mechanic messed this up so I don't have to pay for all the new parts.

 

This is probably your problem or at least part of it. GOOD LUCK

http://forums.maxima.org/showthread....ighlight=p0507

 

thanks but the weird thing is that I don't even have a code. I looked at the car today at the dealer. There are absolutely no codes, the idle is just high and bounces up and down by itself. A new ECM is on backorder as well as a MAF...

 

Isn't the ECU covered under the emissions warranty? If you really need to have it replaced the dealership should not be charging you for it.

 

The idle you describe sounds like a blown maf. Did he spray any cleaner THROUGH the maf? If so, it may be dead. Unplug the maf while the cars idling and report back with what happens.

DF

 

My car is no longer under warranty...also I found out when he cleaned the TB he used carb cleaner and just sprayed it all over. I'm not sure about the MAF, all I know was that it was working fine before the mech started touching the TB. Basically it's not my problem...I will have the dealer fix the car and then take it up with the mech and garage owner. I shouldn't have to pay for any of it...

 

This is only to 8years/80k... His car has 87k.

Sublimer., definitely try and get that money back from the Mech... It sucks that its so much money... Wao, that just plain HURTS.

 

dude i'm sorry to tell you but it's the ECU, it's not the MAF, coils, or IACV. It's the ECU. A bunch of us have all had this problem and time and time again it's the ECU, they are going bad and screwing with your idle. If you change out your IACV your idle might stable out for about 10min, and then will start dancing around like it is now whenever you put it in park or neutral.

See - http://forums.maxima.org/showthread....20#post5531820

 

is there any way to obtain a copy of the factory service manual to prove the mech messed up when cleaning the TB or replacing the IACV?

 

I had a similar problem a year ago and it was the TB going bad.

 

I have the FSM if you want it... Just tell me of a place for me to send it to you. It's big 44MB... PM me.

 

Sorry I missed the 87k part. However, it's not that far over. The dealership may do it out of goodwill. Anyway, doesn't sound like its an ECU issue any more. I'll go and hide now.