2000 Nissan Maxima Revving Problems.

[Coolie]

I have a 2000 Maxima and when the engine temperature is cold, it revs up to 1 1/2 to 2 RPM's smoothly. When the engine warms up and reaches it's normal operating temperature, and I try to rev it up to 1 1/2 to 2 RPM's it starts bouncing. I'm being told it's a vacuum hose, but I don't see anything out of place. I'm wondering if it's the coolant temperature sensor, but the engine is not overheating. I have yet to find a real mechanic who can figure this problem out. Hopefully someone here will know the answer to this issue.

[Ni2s4s0aSnX]

Sounds like a sensor problem to me. But I'm a 240 guy. Check the TPS and IACV and all the other valves that you would check, it doesn't sound like a problem that would be caused by the Coolant Temperature Sensor to me.

[Coolie]

Ok, I checked it out today and I tried disconnecting one of the electrical connections from the throttle position sensor, and it began to rev a little bit smoother. When I reconnected it, it began to give me my initial problem again. I'm wondering if it is a pin, or something inside the sensor that is in incorrectly, because I know it is a new sensor. Any suggestions?

[Ni2s4s0aSnX]

Yeah, it could be a pin or something, or a loose sensor wire. Also, check the IACV. Try taking the cover off of the TPS and take a look at the sensor itself.

[Coolie]

Ok, I checked the TPS everything is in good condition and working fine. I put a new Idle air control valve, and i'm still getting the same problem when the engine warms up. Now i'm assuming my oxygen sensors must be in terrible condition. I have never changed those since I bought the car and I know an oxygen sensor produces no voltage when it is below its normal operating temperature of like 500 degrees. Could I be right about this new assumption?

[NISTECH]

sounds like an airflow meter problem. Pretty common on the 200 and 2001 maxi. Take a look at the part # on the side of the meter itself If it ends in "AD200" you have an old style meter that is known to crap out. There is an updated meter available from the dealer for around 120 bucks, but you will also have to have your ecm reprogrammed for the updated MAF.

[Coolie]

Ok, I bought one of those OBDII scanners today, and came up with the following codes:

1.) P0100: MAF Circuit Fault2.) P0160: O2 sensor Bank 2, Sensor 2

I noticed the plastic connector that connects to the MAF sensor is not locking into place and appears a bit lose, perhaps that may be the cause of the MAF circuit fault? If so, anyone know where I can get a new plastic connector for the wiring harness, because everything else is good.

As for the Oxygen Sensor, the following site lists the TSB and Nissan recommends that I replace both rear sensors in Bank 1 and Bank 2. I'm assuming that this was my original problem.

http://www.nissanhelp.com/Owne...1.htm

[NISTECH]

The maf code may be due to the loose connector but as I said they are known to crap out and you need to look at its part number. It is printed on the meter outer tubing on the side opposite the strut tower. Also regaurding the TSB on O2's , you also need to reprogram the ecm when you replace those or they will burn out again. The reprogram cuts back the amperage in the heater when the cars cold so it goesnt fry from the moisture in the exhuast.