Stumped on an issue......
07-08-2014, 05:36 PM
#1
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Stumped on an issue...... I DD a 2001 Formula with a bone stock ls1 in front of a T56. The only bolt on the car has is a flowmaster catback. It has 128k on the clock, but is very clean and well maintained. Car starts and runs awesome. I run nothing but 93 octane. Gets great fuel mileage, and no smoke.
So here is the issue. Zero codes. When I crowd the car without downshifting, I hear the valves clatter pretty bad. Almost as if I have 87 octane fuel in it. If I stay in it long enough, it will shoot a bank 2 lean code. Very rarely does it shoot the code, but when it does, it will eventually clear itself.
I've tried different fuel stations with no luck. What could be the issue?
So here is the issue. Zero codes. When I crowd the car without downshifting, I hear the valves clatter pretty bad. Almost as if I have 87 octane fuel in it. If I stay in it long enough, it will shoot a bank 2 lean code. Very rarely does it shoot the code, but when it does, it will eventually clear itself.
I've tried different fuel stations with no luck. What could be the issue?
07-08-2014, 08:31 PM
#2
Most likely a bad Maf sensor. As a bad Maf will under report the airflow to the pcm causing lean fueling (positive fuel trims) and will cause the spark timing to be over advanced because the pcm falsely thinks the engine is under less than actual load.
A quick test is to unplug the Maf, and if the fuel trims shift to normal values then replace the Maf.
Russ Kemp
A quick test is to unplug the Maf, and if the fuel trims shift to normal values then replace the Maf.
Russ Kemp