P0171 P0174

[Bob]

Hello,

I’ve got a 2’01 Catera that I’m trying to troubleshoot. Only 2 codes, P0171 and P0174. CHECK ENGINE has been on for 2 mos. now. When starting, it starts just fine without issues. When put into reverse that initial loading onto the motor makes it almost sputter, then it evens out and the car is totally fine, both city and highway.

I made a makeshift smoke machine, propped open the throttle body with some soft vinyl tubing, and pumped smoke in from the intake all the way through the plenum. It was one pass with the smoke machine for a good 7-8 minutes and I did not see any leaks in the front part of the engine bay.

With car on and PIDs on display pressing the accelerator causes MAF value to change on the scanner. Inspection of MAF sensor with eyeballs looks clean and shiny.

— Freeze frame for P0171

engine 2260rpm
calc load 22.7%
coolant 187degF
LT FTRM1 22.7
ST FTRM1 -0.8%
LT FTRM2 21.9%
ST FTRM2 0.0%
VEH SPEED 60MPH
FUEL SYS1 CLSD
FUEL SYS2 CLSD

end of freeze frame —

Cadillac Forum http://bit.ly/1dmCcRY says that it could be a bad MAF sensor. But mine is still giving values. Maybe they’re bad values?

There was also a Catera post someplace about there being a vacuum leak near the brake booster. Videos by ETCG and ScannerDanner show how to check this, but on this car I don’t know where that is.

Vapor recovery is not working right when I fill up on gas. But it’s been like that a long time before the MIL showed up.

What to try?

Thanks

This issue is fixed. Thanks for everyone’s help! :woohoo:

Attachments:

• WP_20150427_16_28_47_Pro.jpg
• WP_20150427_16_31_22_Pro.jpg
• WP_20150427_16_27_59_Pro_Grid.jpg
• WP_20150427_16_28_09_Pro_Grid.jpg

Topic

[Andrew Phillips]

Nice find. Thanks for the updates 🙂

[Author]

Replies