i need some help with a few things and i cant get any answers from people on other websites theyare a** holes,i got a code 91 on my 89 gt the other day and i changed my 02sensor and it went away but i did the koer test and it came up again but the koeo test says 11,i have no cats and i think my car is running rich but cant tell becuz the cats.my book says 91 could be 02 or injectors or regulator,i need some help on this becuz i think this fuel problem is making my car miss a lil.

 

code 11 is system pass,whats your fuel pressure at 35-40.

 

an occiliscope can determine what and where the miss is..could be a secondary or primary ign prob

 

For code 91 to be logged as a KOEO code, requires the failure you see in the KOER self test to be repeated for x times during a few drive cycles. Since a code 41 is not present, the "lean" condition is on the driver side bank. Suggestions:

- Make sure you don't have an exhaust leak on that header causing the lean reading from the O2.
- Check for vacuum leaks that could be focused on that side/bank of the engine.
- Run a cylinder balance test to verify which cylinder(s) are low in output.
- Follow the test diagram for the O2 below and LUK the results.