Need CEL help
 

2000 Boxster S with 75k miles
P1126 and P1133 codes
Replaced AOS and oil filler tube which did have holes in it.
Did fix backfiring through exhaust however still throwing same codes after running for 10-20 miles.
I took following Durametric readings:
FRA1 1.31%
RKAT1 -0.52
FRA2 1.31
RKAT2. -0.56

Mass air flow not running. 1.02v
Mass air flow at idle. 1.32v

Cold engine
Intake air temp. 33.8C
Engine. 28.5C
Oil. 27C

I am not real familiar with using the Durametric software so I'm looking for help on how to troubleshoot from here. Engine is running fine and I don't understand why the CEL comes on repeatitly after resetting it.

Ron

Look at this thread: P1123, P1125, P1128 codes - 986 Series (Boxster, Boxster S) - RennTech.org Forums

A bunch of possibilities listed
- MAF failed
- Intake air system leaking
– Fuel pressure too low
– Volume supply of fuel pump too low
– Fuel injectors fouled
- Exhaust system leak

Check in that order.

With my long term trim numbers (RKAT) being negative does that mean I am running rich and the correction is leaning out the fuel mixture? Before I replaced my "holely" oil fill tube my RKAT values were + 3 something.

BTW - I have cleaned my MAF with MAF cleaner.