1997 trans am with the le2 heads, gm847 cam, 30lb accel injectors, Lt headers. We did the install of everything over the past few months. recently the car has been running but not up to par at any means. the car backfires anytime gas is given. so far we have changed the plugs and made sure the wires were correct. Hooked up the scan tool and got the codes 0335 and 0336 all being crank sensor issues. we replaced the crank sensor as well. There has been no change in the way its running. please help.........

BTW: searched the backfiring topic already and tried all the different fixes but still nothing

 

what kind of headers? pacesetter, if so i had to replace my 02's for a similar problem due to the coating burning off on initial start up and coating the 02's

 

I hate to say it but P0335 & P0336 are indicative of opti issues as is the backfiring. Actually P0336 points to a bad low resolution pulse stream out from the opti.

 

ha its a brand new opti spark too. good thing i can get opti's done in about 3 hrs time.

 

BTW all the spark plugs were black as night with the exception of cylinder 5

 

Black plugs means your running rich and probably fouled the plugs out. Just out of curiosity, have you had the computer tuned yet?? If not, that's your problem. These cars tend to run pig rich after a big cam swap and without a tune. Also, if you already have a tune, is the 4 wire opti harness new also??

 

so... just out of curiosity what type of headers?

 

yea computer is a mail order tune now, yep and a new harness and opti

 

bump what else should i try

 

Pacesetter Long Tubes

 

Try another set of injectors, accels are garbage.

o2's don't make a difference at WOT, as far as I know.

Do me a quick favor. It only takes 15 minutes to swap the injectors.

Put in the stockers and the stock tune and see how it runs.

Just because your opti is new doesn't mean it's in good working order.

Do an opti test and make sure you're getting the proper voltage.

 

well lol the stock injectors were sold haha so thats out of the question but like i said before there or no codes present right now and when running.

 

I had the same problem as you. I had 30# svo's. On a whim I swapped the stock tune and injectors back in, and the car was cured. Before it would mis, backfire, stall and not start until it sat for a bit, etc...

I kept thinking opti/ignition. It was the injectors.

 

^^^ do you think they were just dumping too much fuel

 

your right, but as far as i know the computer does use the long term fuel trims during wot to help regulate fuel, and he said anytime he gives it gas not just wot. i had a very similar problem when i first finished my build and i got advice from bryan at pcmforless to swap o2's and that fixed it