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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Pontiac
Satisfied Customers: 1526
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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Pontiac Grand Prix GT: I have a 2002 grand prix gt, that

Customer Question

HI I have a 2002 grand prix gt, that will accelerate fine in park and neutral but in gear it will not accelerate and misses. The trac off light comes on, but the check engine light has not come on?
Submitted: 2 years ago.
Category: Pontiac
Expert:  Gary replied 2 years ago.
Welcome! My name is ***** ***** I will do my best to assist you with this problem.
when in gear and trying to drive does the engine bogg down like is choking out ?
there are NO codes in the computers history or current set at all ?
any codes in the ABS ?
Customer: replied 2 years ago.
Yes the engine gets to around 2000 rpms and just boggs down and no codes or check engine light has not come on. The only light I get is the low trac light comes on when in gear and trying to accel. and once you put it back in neutral the light goes out.
Expert:  Gary replied 2 years ago.
are there any ABS codes set ?
the traction control is run through the ABS and if the traction control comes on there should be a code
if the converter is brand new is the fuel filter new ?
what size engine is in this car ?
any idea what the fuel pressure is key ON engine OFF ?
Customer: replied 2 years ago.
Fuel filter is not new, the engine is the 3800 v6. Not sure how to check fuel pressure on this. If there is a abs code won't the abs light be on? My code reader is not a real expensive one, so may no be able to pick up these codes. Where is the fuel filter on this engine?
Expert:  Gary replied 2 years ago.
what size engine is in this car ?
Customer: replied 2 years ago.
It is the 3800 v6
Expert:  Gary replied 2 years ago.
The fuel filter is located on the cross member just in front of the fuel tank
cut and paste this link for the picture of it
change the fuel filter and see if the power comes back!1054&authkey=!AKRC3DLpWILcPKg&v=3&ithint=photo%2cgif
if after changing the fuel filter it still does this there is a test port on the fuel rail on the engine see if the fuel pressure is reading 53 - 59 key ON engine OFF if its not then the fuel pump is bad
Customer: replied 2 years ago.
Ok thanks will try those.
Expert:  Gary replied 2 years ago.
ok let me know
you can always get me back through this post with any follow up anytime with this question even after you rate us here at Justanswer !
Customer: replied 2 years ago.
HI Gary,Replaced the fuel filter and no improvement.
Fuel pressure tested at 46 lbs., this is below what you said it should be, do you feel that is enough to make the car run this way?
Expert:  Gary replied 2 years ago.
it could be
very hard to tell right now
if you unplug the MAF will it rev up ?
Customer: replied 2 years ago.
Unpluged the maf and did not help, seemed worse
Customer: replied 2 years ago.
What would you suggest I check now. Running out of patience with this vehicle. Still can't understand why I am not getting a check engine light, as bad a this thing is running. Does not make any sense to me.
Expert:  Juan Crespo replied 2 years ago.
Hi there. Different expert here. You might not be getting a CEL for various reasons; bad bulb, bad circuit, no OBD-II codes, just to name a few. The main function of the CEL is to warn the driver when something is making the engine emit at least 1 1/2 times more emissions than allowed. Then there is the whole OBD-II protocol to consider as well.In any case, the "Traction Low" warning might be giving us a clue of what the real issue is. Having that in mind, what I would like you to do is turn the ignition off, open the hood and disconnect the ECBM (see attached graphic). Then start the engine and see if you can now get normal power out of it. If the power is back, then you can either shotgun the repair and replace the EBCM and see if that fixes the issue, or you could try to get a hold of a scan tool capable of communicating with the ECBM as well as with the PCM so I could guide you through a systematic diagnosis process. Best Regards.
Expert:  Juan Crespo replied 2 years ago.
I guess the system did not accept the attachment the first time. Let's try that again.