2001 Maxima ECM/Idle/Etc Issue (Updated 7/20)

[mrm121]

Hey guys!

So driving to the airport my car started doing weird things. It was idling at 2000 rpms, then it would sometimes start bouncing around between 1k and 2k rmps and it would also sometimes just die while idling. I have done some research and it seems the IAC Valve is probably to blame. The main questions I have is whether my ECM is toast (I heard an electrical "pop" while restarting and giving it gas and I assume that was the ECM. Electrical burn smell after the pop.). The other question is why my cluctch pedal would get stuck down. When I was getting to parking, the clutch got less and less useful and I was having to do a little forcing into gear. When I got back from the trip, the clutch pedal is at the floor and there doesn't seem to be any clutch response. It started and idled at 2k rpm, but no clutch at all. Any ideas???

Also, any suggestions on getting it fixed would be appreciated. I hear this could be $2000 at the dealership and I am a pretty handy guy under the hood so maybe doing some of the labor myself would help?

[maximapwnage]

hey have you checked your clutch fluid

[mrm121]

Called a tow truck today. While I was waiting I checked the clutch and it is back to normal. Maybe it got a little overheated with everything. I also checked the ecm/ecu and as I suspected, one of the big black components has a crack and a littleblack on the white letters. I'll have to get that repaired and replace the IAC valve and throttle position sensor. Any way to prevent the ecu from blowing in the future? It seems like I read something about unplugging the electric mounts but that may have been unrelated...

[loystock]

The IACV probably shorted out and 'fried' the ECU based on the symptoms provided. The IACV stepper motor and, if applicable on cars with electronic engine mount, their drivers (power transistors) are in the ECU. So if the IACV or electronic engine mount coils are shorted out, it can kill the ECU. You can buy new or used ECU but for warranty, you have to replace the IACV and TPS. The resistance of a good IACV coil is 30 ohms but most likely, you'll see zero (short circuit). If you are concerned about the electronic engine mount causing ECU failure in thew future, you can disconnect it. The electronic engine mounts dampens the engine vibration at idle and stiffens at higher RPM. The clutch is a different story and the suggestion of OP.

[mrm121]

Dealer called this morning. Bad ECM/ECU (as I expected). He did say that the IAC Valve was still good, but I will be replacing it regardless. They wanted $1400 for just the ECM. I am going to drive it home and repair it myself. I will use one of these to repair the ECM:

http://www.autoecu.com/ - $305 (Lifetime Warranty) - "B-" BBB rating
http://circuitboardmedics.com - $199 (1 Year Warranty) - "A-" BBB rating
http://www.aesmodules.com - $? ("Full Warranty") - "A-" BBB rating
http://www.goecm.com - $495 ($100 core refund, Lifetime Warranty) - "B" BBB rating

I am leaning towards the second. They also send instructions for the relearning of the new IAC Valve. Not sure where I will get the IAC or TPS...maybe RockAuto.com? They seem to be simple enough to replace by myself. If everything goes according to plan, I could get everything done for somewhere in the neighborhood of $500 rather than $1400 for just the ECM. Hopefully I will get at least a few more months out of the Max' before I sell it and get something newer.

[mrm121]

Alright. I installed the new Idle Air Control Valve, Throttle Position Sensor, and repaired ECU/ECM. I also cleaned the throttle body while I had it out. The car is running GREAT!...except for one small issue. if you slowly rev the engine, the RPMs will bounce starting around 2000 RPM. If you don't continue to push the pedal (holding it stationary), it will continue to bounce until you let off the accelerator or press it in further. Any ideas on why this would happen???

I have done the re-learn process. I am considering disconnecting the battery and re-doing the relearn process.

[ERUOTANEN]

My 2000 Maxima has been on the shelf since middle of June. First it would ocassionally not start. If it did start, it would run until you stopped it. Took it to my mechanics who thought fuel pump, which it was not. They also checked all the obvious sensors. Then I had the ECM rebuilt at ECM Depot ($400). Mechanics put it back in, still would not run. Sent back to ECM Depot and they checked it and sent it back. Meachanic put it back in, still would not run. Took my older NATS key, turned to ON for 5 seconds and then OFF, did this 3 times and car started and ran great. For a day. Next day at 65MPH the engine died. Dragged to dealer. told him I suspected NATS key, so I had some new ones programmed. Still ran like crap. Dealer checked all codes and replaced Crankshaft sensor, then he gave up unless I wanted to throw big $$ without a guarantee cure. So I drove the car home, but soon after you start the car it starts missing, running rough, stalling. Will restart and run rough again so I made it the 10 miles home. Put in some gas treatment and topped off the tank with premium. Started in the yard and ran for 10 minutes at 2-3000 rpm, and it seemed OK. I am now thinking Mass air flow transmitter as my 94 MAX had a similar problem, no error code was given for mass flow transmitter, but replacing it fixed the problem and the car ran great until my daughter totalled it. (Anyone needs parts, that one is sitting in the yard; using it for parts on the 94 Max that my daughter now drives)
Any ideas on my 2000 MAX problems? thanks,

[wyliecaver]

mrm121,

I am in the same situation with my 01 Maxima and am considering circuit board medics. Is this the service you ended up using on yours? Is your car still running fine, no P0505 code?? I had pulled my ecm a while back and inspected it thinking I would find a burned chip but it looked perfect inside. Something still has to be wrong with it though because I have a new throttle body from the dealerships repair and have never been able to get the P0505 code to go away or relearn procedure to take. I mainly wanted to inquire if you were satisfied with the service and your car was running as it should a month later.

Thanks