That map sensor will not work on your car, that is for a newer GM version. The map sensor reads the vacuum in the intake manifold which helps the ecm to calculate fuel delivery and timing. The mass air sensor measures the air entering the engine and also helps the ecm to calculate fuel and timing. Check all your vacuum lines and connections which would allow extra air to enter the engine and cause a high idle rpm.
The MAF sensor should be right around the throttle body. super easy to change but relativly expensive. I would think if that was bad it would high rev all the time not just in nuetral. Mine got some type of fluid on it before and started pulling the car forward when I had the breaks on. kept self revving to over 3,000RPMs. took it out cleaned it with electrical cleaner dryed it and now it works fine. Try cleaning it first before replacing. If thats even the problem.
Thank you for your answers, I will try to clean the sensor at first before I will replace it, also its very hard to find that sensor, Rockauto.com has one and wants 50 euros included shipping, not to bad at all
How can I get the sensor out? Only pulling or like that? Because the sensor is plugged in a metall box (with 4 srews when I remember) and I only see the backside of the sensor if Iam right^^
I would be very happy if someone can write here how I have to pull out that sensor without destroying it
The engine runs somethimes in a high level and some days or weeks it runs normal
Iam looking forward to hear from you
Last edited by Firebird1987; 03-05-2012 at 04:56 AM.
Two days ago, I checked all the sensor that are near the motor, also the sensors near the throttle. I cleaned them all with an electronic cleaning spray and now the engine runs fine and well.......with 700-750 rpm
I hope that I have solved the problem for good
Yesterday I cleaned the trottle body,cleaned the TPS sensor and replaced the idle regulator valve but the engine runs still somethimes with 1000-1500 rpm in the idle
Where is the MAF sensor exactly? Is the MAF sensor this sensor that is left behind the engine with a red plastic mounting? When yes, then it must be this one that is very hard to remove, because it is surrounded by some metal parts, I think^^
Plugs, sparks and airfilter are new, the next week I will change the fuelfilter and change the catalyst by a magnaflow katalyst.
Last edited by Firebird1987; 08-02-2012 at 03:20 PM.
Today I changed the MAP sensor, but the engine runs still at 1500 rpm, but not so often.
When I start the engine the service engine soon sign still is on and turns of, then again on etc......, but the engine runs better now with a better idle.
I drove some miles and shifted in the neutral ( 5 speed manuel) and the engine was running at 1500rpm again (but not immediately), but when I stopped at the gas station the engine came slow down to 700-800 rpm^^
Wednesday I will change the catalyst, the fuel filter and the cooling water (its brown and smells^^)
A buddy told me that maybe the catalyst is broken inside, that means that the oxygensensor has wrong values, but can that be for real? I dont think so^^
Again: I changed the TPS sensor, changed the MAP sensor and cleaned the throttle body, but nothing worked, or not perfect
Lets see whats going on at wednesday.
Last edited by Firebird1987; 08-29-2012 at 02:01 PM.
The thing about a "speed density" motor (the 3.4 is one) is that if you introduce extra air into the engine by any means, this will report a drop in pressure and the PCM will add fuel to compensate (much like hitting the gas pedal).
This means that breaks in hosing are harder to diagnose but it will also mean if you break a line the engine will continue to run (unlike an MAF-enabled system).
Again check all plastic hard lines and fittings. the T fitting on top of the 3.4 manifold ripped on my engine a long time ago and the engine would idle about 500 rpm higher than it was supposed to. I wrapped some electrical tape around it and it almost fixed the problem (only idled around 100-200 rpm higher).