Check Engine Light
Thread Starter
Pro
Joined: Oct 2005
Posts: 623
Likes: 0
From: SpringHill Florida
Check Engine Light
My 99 coupe is coding P0171 and P0174 Fuel trim system lean Bank 1 and 2. I reset it and tightened the gas cap to make sure this was not the problem and it came back after a few miles. Reset again and drove it for 150 miles and it came back with only the P0171 code.Any ideas??
could a vacuum leak cause this?I think I have to fix the dreaded a/c vac line as the defrost lets air through during the a/c cycle.
could a vacuum leak cause this?I think I have to fix the dreaded a/c vac line as the defrost lets air through during the a/c cycle.
Melting Slicks
Joined: Jul 2007
Posts: 2,087
Likes: 11
From: Austin TX
Ive got the same codes, but I got them after I had my cam installed and tuned. In my case its probably in the LTFT, in yours, it could be a vacuum leak, post MAF. Check around the injectors, intake manifold, TB, or anything else that could become loose
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Mr lead foot is having simular issues and it may be somewhat related to a POOR ground issue The O2 sensors are grounded at G-105/G-203.
If you have:
- Checked the intake ducting between the MAF and TB for 100% tightness!
- Check the ENTIRE PCV tubing and fittings for deterioration/damage (very common issue)
- Other vacuum leaks
Make sure that the Grounds for the O2 sensors are in good shape and tight!!
Hows those HIDs doing????
Bill Curlee
If you have:
- Checked the intake ducting between the MAF and TB for 100% tightness!
- Check the ENTIRE PCV tubing and fittings for deterioration/damage (very common issue)
- Other vacuum leaks
Make sure that the Grounds for the O2 sensors are in good shape and tight!!
Hows those HIDs doing????
Bill Curlee
