Check engine light help

[timm]

2003 Denali Check engine light help

Hello all and i would like to thank you in advance for any input.

2003 Denali

problem- check engine light is on, very rough start up usually when the temp is below 40. After it warms up it is fine, but can feel a fine missing of the plugs I think.

solution attempt-went to autozone. they hooked up the scan tool said lean bank 1 bank 2. tuned up my truck with AC Delco iridium plugs gapped at .40, put new wires in(I think duralast), replaced the Mass Air flow sensor because they said it was bad(they disconnected the sensor while the truck was running and it stayed running so they said it was bad), replaced fuel filter.

Now, I am in PA, so the temperatures are really fluctuating so its hard to tell whats going on because it usually just runs really crappy at first in the bitter cold. I did notice though after doing all of these things that the truck still feels like its missing and the check engine light is still on(I did the work this past friday and the light is still on as of today) I don't know what else to do or check?

thanks for any input!

 

[greenhornet]

It is worth getting your fuel pressure tested,GM say's 55 to 62 psi but better to be closer to 60+lbs.s

 

[timm]

thank you greenhornet! Is there a sensor for the fuel pressure? If so, let me guess its located on top of the tank that I just had dropped in october to have my fuel pump replaced!

---------- Post added at 08:52 PM ---------- Previous post was at 08:37 PM ----------

It is worth getting your fuel pressure tested,GM say's 55 to 62 psi but better to be closer to 60+lbs.s

Just got back from autozone. code reader says bad fuel tank pressure sensor. Your good!! thanks. now....how to replace?

 

[bkboatnsleds]

I have to replace mine too..

and yep - I just dropped the tank about 6 weeks ago..

its right on top the tank - its got to come down ..

 

[chip]

I will say this: Taking the tank down is not as bad as it could be. I had to drop mine not too long ago, and I was able to get it down and back up by myself with relative ease. Still sucks, but hopefully it helps.

 

[greenhornet]

The fuel pressure test port is on the fuel rail right side engine (pass side) needs a special fitting and gauge.

 

[Systems1x]

Lean on bank 1 and 2, p0171 & p0174?.. Check for vacuum leaks around/on the intake itself. I've had lots of issues with those intakes and gaskets. Could be fuel, but I always start with vacuum.. Start the truck, get some carb cleaner or brake clean, and spray the intake around all the seams and cracks and note any difference in idle speed. Check all the intake duct clamps too. If all that looks good, get a pressure gauge and check your fuel pressure. Let me know what you find...