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2004 GTP strange problem

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dakcornholio

New member
So I have a 2004 GP GTP with 52k miles. I have recently noticed the car doing something very strange and I can't find any similar problems online. When I put the car in drive and start going the car starts moving and then suddenly stops accelerating. The RPM's start dropping (900-400) and the car seems like it is going to die. The further I push on the gas the worse it sounds. Then while I am still pushing on the gas it finally catches up and the car suddenly accelerates (usually squealing the tires). The car also did it today while in reverse. It is a very intermittent problem and usually occurs when the car is warmed up but it seems to be getting worse. This only seems to happen just after shifting the car into gear. It has never happened after I have been driving for a while.

Car is stock except for a 180* T-Stat and Spectre air intake. I also already cleaned the throttle body. The transmission shifts smooth and there is no slippage. Has anyone ever heard of this problem or have any suggestion to what it might be? The next thing I am going to do is change the fuel filter and plugs but I seriously doubt they have anything to do with it. Any advice would be much appreciated.
 


unplug your mass air flow sensor. it will turn on the MIL but it will also default it to speed density "mode" which basically determins the amount of air entering the intake without the use of the maf. anyways try driving it with the sensor unplugged and see if the concern goes away, if it does your gonna need a maf. let me know if this works at all. these cars also have an electronic throttle body and sometimes have issues with 1 of the 2 electronic throttle position sensors (part of the throttle body assembly) unfortuntatly this is harder to diagnose than a MAF issue if you need further assistance i can pull a diagnostic chart from my GM database to see if that will help you.
 
It is not throwing any codes what so ever. I will unplug the MAF sensor and give that a try. What does MIL stand for? I will update you with what happens
 
Ok, so I unplugged the MAF sensor and drove around with it unplugged. This completely magnified the problem. The car did the same thing it was doing but more frequent and for longer durations. No check engine light came on the entire time I was driving it (weird). On a side note my AC also did not work with the sensor unplugged but started working as soon as it was plugged back in. I read on some other GP forums about cleaning the MAF sensor. I went and got some MAF cleaner to see if that will fix the problem because it is a whole lot cheaper than buying a new sensor. I am thinking there may be a bad connection or the MAF sensor is just going out. Let me know what you think, thanks.
 


If the problem still existed with the MAF unplugged then im betting thats not the problem, Do you have anything to scan with?
 
No I don't have anything to scan with but would I be able to if there is no check engine light? I did clean the MAF sensor and I wasn't able to get it duplicate the problem. I seriously doubt that fixed it but I will have to drive it around more to see if it does it again.
 
your ac stopped working on your car because the MAF sensor has an integrated intake air temp sensor. and when unplugged defaults to negative 41*F. its a safety feature so the evaporator core does not freeze. this also causes the engine to run very rich. i wonder if the oxygen sensors are working too "slow" and cant read the oxygen content in the exhaust fast enough to control the fuel flow to the engine. (thats just me thinking out loud) you really do need a scanner like they said so you can actually read data as the car is running and determine what is not reading properly.
 
The car is still having the problem so I took it to a mechanic shop today and had it scanned. He told me there were no history codes and everything checked out fine. I guess I am just going to have to wait for a check engine light to come on since this is such an isolated problem and nobody has heard of it before. Thanks for all the input!
 


Two of them.

One in the rear manifold and one after the converter in the downpipe, right before the catback flange.
 
FYI, dunno if the dealer charged you for the scan, but they typically do. Local parts stores like advance, oreilly's, etc... have a scanner you can use for free.
 
Yeah a mechanic I know did the scan for free. Thanks for the input I will keep you posted on what happens after I replace it. I probably won't get around to to until next week or so.
 


So I did not end up changing the O2 sensor. I didn't want to take the chance of wasting money since they are about $70.00 a sensor. I would be really surprised if it is the sensor because there is no check engine light and I am still getting over 20mpg. I did end up changing the spark plugs, wires, and fuel filter (It did not fix the problem). The has started idling funny when you start it up after it has been warmed up but still no check engine light. Today when I was in park it started idling down to about 500-400 rpms and was acting like it was going to die. The rpms suddenly jumped to about 2500 rpms without me pushing on the gas and went back down to normal idle. I am also still hearing quite a bit of pinging so I am not sure if the two problems are related.
 
And 70 bones is cheaper then a new motor. Letting the problem persist because you don't want to spend money to fix it makes zero sense
 
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