P0172 Code

[01gtp23]

My car is running really shitty with no power(puffing black smoke and stinking up the cabin ... ) i know the code i have is P0172 Bank 1 too rich, which could either be the MAF or the 02 sensor are both of these testable measuring the resistance or something. Or can someone tell me which part goes bad usually on the 01 gtp's I have alldatadiy so thats where i got my information from.
Update: I replaced both 02 sensors, still have the chk engine light and the idle is very weird, sporatic.

[tblake]

HAHA, Stinky Cabin..... Nice

You better get the problem resolved before the Cat Converter burns up.

I hate to say this but you probably did not have to replace the O2 sensors, and defenatly did not have to replace the rear (post cat) sensor.

Try unplugging the MAF sensor and driving the car.

Also remove the vacuum hose off the fuel pressure regulator, turn the key to on, and check for gas shooting out.

finally I would check fuel pressure on this one.

[BNaylor]

Wow! Two P0172 DTCs in one day. I agree with Tim start with the MAF sensor.

Check all vacuum hoses at intake system.
PCV Valve
Possible throttle body blockage (clean input screen and body)
IAC (idle air controller valve)
Check fuel injectors (bad o-ring seal)
MAF sensor
EGR valve
Check 02 sensor (before CAT)

[2000gpgtx]

I'll second tblake on the fuel pressure regulator as I've seen a number barfed in VIN 1 and K engines recently and the driveability symptoms described match to a tee .. engine idling, remove vacuum hose at pressure regulator and look for raw fuel getting drawn into it. Most of the 3.8Ls I've encountered showed no signs of regulator failure until there was a vacuum source to 'pull' the diaphram, at which point the raw fuel was drawn directly into the intake uncontrolled and the PCM is unable to compensate for the additional fuel source popping the P0172 as it exceeds the rich threshold.

[01gtp23]

Ok, so ive done the fuel regulator test and i dont see or smell any fuel coming out of the hose and i dont have a pressure tester atm... I bought a new regulator and i'm just waiting for the engine to cool down and then ill update my situation, thx guys

[BNaylor]

I guess it is better to waste money on expensive little parts that may not fix your issue then investing in a fuel pressure gauge which will help prove the fuel pressure regulator (FPR) is bad or not the issue by watching the fuel pressure readings with vacuum on and off at the FPR, fuel pump prime and at idle.

[TheBobsHere]

If the cat is clogged it'll run rich which will clog it more and due to lack of airflow can burn the MAF right up. Also, I'd put the old O2 sensors back in till you get the situation figured out or you may contaminate the new sensors with the un-burnt fuel and that'll be money down the drain.
The GM MAF works on frequency and from my knowledge cant be tested with a meter, you need a scope.

[BNaylor]

You really don't need any fancy test equipment to rule out a MAF sensor issue on a L67 or L36 SII 3800 engine. As tblake suggested just unplug it with engine off, then restart and see if driveability returns. It will default to preprogrammed MAF/VAF tables. I've run with the MAF sensor in my GTP disconnected for about week until the part arrived. The idle may be a little rough until the engine warms up but better than nothing.

The best way to check for a rich or lean trim giving a P0172 or P0171 DTC indication and what direction to head is check the short and long term fuel trims with a scan tool capable of providing that data.

[TheBobsHere]

You should also check the MAP sensor, it's common for them to get out of range and throw the system off. I've seen them go bad and cause this exact sort of problem. Have the catalytic converter checked for blockage if the MAP sensor doesn't help.

[TheBobsHere]

BNaylor, I've seen the MAF go bad and make the car run worse in limp mode after unplugging the sensor. So thats not always a surefire test method.

[BNaylor]

Since this is assumably a '01 GTP the CAT converter is a possibility. If our new or recent members would just take the time to review the Tips & Maintenance subforum or old threads in history many answers are already posted. See thread below.

Click here

Hopefully he has no more than 120K miles or 10 years whichever comes first because converter testing and replacement could be free of charge at the GM dealership.

[TheBobsHere]

It's always a good idea to check the service bulletins before throwing down money on a guess.

[01gtp23]

Well my baby's back up now Popped the new regulator in fired it up, ran shitty for a minute then back to its old self ! God I love the informative peeps on this forum, I needed to replace the sensors and the regualtor anyways seeing how it has 130,000 miles on it !:sarcasm1:

[TheBobsHere]

tblake got it in one, impressive.

[BNaylor]

Originally Posted by TheBobsHere

BNaylor, I've seen the MAF go bad and make the car run worse in limp mode after unplugging the sensor. So thats not always a surefire test method.

You have a point but it really doesn't make any difference since it is a cheap test and easy to do on the MAF sensor. It does work most of the time or otherwise we would not suggest doing it.

In this member's case below he was dead in the water in a parking lot at a shopping center and was able to do more than limp home. See thread below gong back to 2005 and we have many more documented cases on AF so the advice speaks for itself but thanks for your opinion and contributing to the forum.

Click here