Currently dealing with P0171 and P0174, both banks are running lean. I have a new genuine BOSCHE MAF sensor that I put in less than a year ago so I am thinking vacuum leak or fuel filter. I'll probably run a pressure test after work to see if I can rule that out.

Noticeable symptoms, occasionally on accelerating the car will hiccup ~3K RPM and mileage has dropped by about 20%

Anybody have any ideas?

 

I would look around the base of the throttle body for a crack or small leak.

 

Did the fuel pressure test and pressure held right at ~57psi so that's ruled out I guess.

Next step: Get some cigars for me and my friends and find the vacuum leak!

 

Haven't found the leak yet. MAF sensor is unplugged currently to see if the lean codes come back while the car is running on the default maps. I ran down a stretch and got accelerated a few times to recreate the occasional jerking I've felt. No luck and no codes so far.

I've already cleaned the MAF once, hopefully it didn't go bad.

 

Update:

Found the elbow from the Needswings intake pipe to the Throttle body below the MAF sensor was loose. Both codes went away for about 100 miles, P0171 Lean Bank 1 is still showing. Possibly another vacuum leak somewhere, really wish I had access to a smoke machine to make this easier.

 

Can use a squirt gun or catsup bottle full of soapy water. Engine should slow down when you hit the leak. And if you don't find it you can still have fun.

GM used to have a fixed fast idle position to help with diagnosis, don't know about CJF.

 

Or use an unlit propane torch - engine will speed up when you find the leak .....

 

Problem with a good computer car is that it can change very fast to maintain a specified idle speed. You can even pull a plug wire and there will be little change except for a misfire code being set.

In the '80s a GM ALDL could sense addition of a scan tool and would set a "service mode" that would act more like a carb for troubleshooting. Can the Crossfire do this ?

 

If I had a second set of eyes I could watch the fuel trims while testing with propane. I'll try the soapy water.

Since I have fixed the main leak my mileage has gone back up.