2002 Pontiac Grand Prix Repair Question
Mileage: 110,000 miles.
Car has no power and seems to run lean, possible timing issue?
Asked by v84u2nvAnswer
what is the back pressure reading for the cat converter. it can look good but still can be bad
Roy
there is less than 3 lbs, but i have even gone as far as to completely unbolt cat conv, from car and still same results
Really?!? thats it??? no other replies??
forgot to mention, replaced PCM as well , still the same. also after takin car back out again, now have code P0404 present , replaced EGR. cleared codes and comes back.
Did you check to make sure the egr passage going into the intake was clear?
Do you have acess to a scanner to check fuel trims?
did you check the fuel pressure?? it needs to be around 4 lbs.
3 psi back pressure is a lot. was it any better without the cat??
Roy
Yes, I have checked egr passage going into intake, absolutley clean. I have access to Solus scan tool. I checked fuel pressure at idle as well as driving down the road, never drops below 50 psi. 4 lbs , i think you are mistaken, and 3 lbs and below of back presure i was told is acceptible. there was no change even when i unbolted the cat conv. from the car.
did you check the compression?? it needs to be above 120 and even.
the only other thing i can think is fuel integrity.
wondering if there is some bad fuel that may have contaminated the injectors.
Roy
Hi Roy , it does state that I did do a compression test. it is well above 120 psi. As far as bad fuel comtaminating the injectors I find unlikely due to the fact that the engine only faults when under a load ie: climbing a hill or accelrating. If the fuel was bad or inj. were containated logic would dictate that it would do this in all instances. I do believe it is a fuel delivery issue,as stated , seems to be lean on spark plugs and exhaust only under a load like its loosing signal to the injectors. what do you think about the re-occuring P0404 code? the only clue I have. has to do with the EGR circut, but that was replaced and all passages were clear and clean.
did the 404 return??
my gut is at 2 thingd here. the injectors may need to be cleaned, not with additive but with direct injection.
the other is the cat. i know you said other guys said 3 lbs is ok. it has never been ok with me as anything above 1 to 1.5 is not acceptable in my world.
try the cleaning first.
Roy