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My 2004 Grand Prix GT2 began making a strange noise which I would describe as a whirring sound when I step on the gas. I decided to see if I couyld hear it when I was in park. I have now found that the engine will not rev above 3500 RPM and will sit at that with the gas pedal to the mat. Any ideas? Could it just be a sensor?
The whirring noise could be because idler pulley/tensioner pulley/water pump pulley or maybe the power steering fluid is low. I would remove the belt and start it up, see if the noise is gone. If so, then its a belt driven issue (pulley, pump, etc...). If not, it could be the transmission.
As for it not revving up past 3500, its designed to do that. If the trans is in Park or Neutral, the Powertrain Control Module limits RPMs to 3500. As long as it goes past 3500 while in gear, you are OK.
I went out and checked on the RPM issue after I posted the question as I thought this might be the case with the newer vehicle (88 Lesabre did not have this feature). You're right because it did rev past the 35 when moving. The whirring is an intermittent thing, however, it is occurring more and more. Seems to disappear if I shift into 2nd. Should also mention that I have checked all fluid levels and they are OK. Also, the sound is not present when engine is in park or neutral.
Are you sure you checked the power steering? I ask because the Power Steering reservoir is very difficult to get to. You need to look at the dipstick that is attached to the cap (not trying to insult you, but power steering noises are very common on these cars due to low fluid).
I have checked all the fluids and they are all ok. Sound is only present when gas is applied when moving. Nothing when just turning without applying gas.
So the noise goes away in second gear?
Does it come back in 3rd or 4th?
Will it do it in first gear if you let off the gas or only while accelerating?
Only when gas is being applied and it is present in all gears, just not as noticeable in 2nd.
Can you put the e-brake on and put the car in drive while pushing the brake pedal to stop the car and rev the engine while listening for the noise (use a long screwdriver pressed against your ear)? Put it against the alternator, water pump, top of transmission, etc. See if you can pinpoint the noise. All of the aforementioned can make a whining/whirring sound along with the power steering pump.