Perplexing Problem
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From: Winter Springs
Perplexing Problem First off , 8k miles on an forged LQ9 408 , AFR heads and all trick parts .
#3 cylinder is running very rich , all other cylinders running normal acording to the plugs .
A/F on the driver side is 10.2-10.5 and passanger side is 13.0 and im pretty sure its because of #3 cylinder burning so rich its black with sute and actually fouls out the plug after 200 miles or so .
When i stab the gas it puts out a black cloud of fuel and ppl have told me its a fuel cloud and not oil .
There is no oil present on the plug .
Compression check , 202-208 psi in all cylinders .
Leak down tested out to 3-5% in all cylinders .
I swapped the coils around and no difference .
I swapped the injectors around and no difference .
What else would cause ONLY the #3 cylinder to run so rich ?
#3 cylinder is running very rich , all other cylinders running normal acording to the plugs .
A/F on the driver side is 10.2-10.5 and passanger side is 13.0 and im pretty sure its because of #3 cylinder burning so rich its black with sute and actually fouls out the plug after 200 miles or so .
When i stab the gas it puts out a black cloud of fuel and ppl have told me its a fuel cloud and not oil .
There is no oil present on the plug .
Compression check , 202-208 psi in all cylinders .
Leak down tested out to 3-5% in all cylinders .
I swapped the coils around and no difference .
I swapped the injectors around and no difference .
What else would cause ONLY the #3 cylinder to run so rich ?
The only thing left to swap is the plug and the wire from that cylinder(if you haven't already). If that doesn't move the problem to another cylinder you need to get a noid light and check to see that the injector is firing properly. But, I don't think this is the problem b/c you should get a check engine light for injector circuit malfunction.
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From: Winter Springs
Originally Posted by 5.3LJimmy
The only thing left to swap is the plug and the wire from that cylinder(if you haven't already). If that doesn't move the problem to another cylinder you need to get a noid light and check to see that the injector is firing properly. But, I don't think this is the problem b/c you should get a check engine light for injector circuit malfunction.
Originally Posted by JAY ROD
is one of the pushrods too long on that cylinder?
Compression and leak down tests came back even across the board .
Im going to tear it down tomorrow and see if i can find anything wrong with anything ,, hehe
Again , why would only one cylinder be running rich and the rest normal .
I have a good working knowlage of how a motor works but dam if i can figure this out
I was hoping someone on this board had this kind of issue before .
