Backfire Issue
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 1,158
Likes: 6
From: Winter Springs Fla
Backfire Issue
What would make a motor backfire through the pipes at 5400 rpms in any gear ?
This stupid problem has been rearing its head for 6 weeks now .
It usaly happens at wot but has backfired at 3/4 throttle .
The local shop had it for 2 weeks and couldnt figure it out either .
Ive tried swaping out the MAF , Computer , crank sensor , cam sensor , ive checked the wiring harness for issues and replaced a couple falty wires , changed spark plugs , swapped coil packs , built a new fuel system .
The car was running great right before i spun a rod bearing ,, had the motor rebuilt by Shaker , reassembled the car and now i get a backfire every time i go 3/4 to full throttle .
The car runs great other wise and there are no typical signs of a problem .
A/f is 12.750ish right up to the time the car does this .
When the car backfires it stops the logging and the car shuts off and stumbles from 5400 down to 4000 rpms then trys to catchback up to itself but cant .
Im at a total loss here and will try anything i can to get over this issue .
HELP ! ! !
This stupid problem has been rearing its head for 6 weeks now .
It usaly happens at wot but has backfired at 3/4 throttle .
The local shop had it for 2 weeks and couldnt figure it out either .
Ive tried swaping out the MAF , Computer , crank sensor , cam sensor , ive checked the wiring harness for issues and replaced a couple falty wires , changed spark plugs , swapped coil packs , built a new fuel system .
The car was running great right before i spun a rod bearing ,, had the motor rebuilt by Shaker , reassembled the car and now i get a backfire every time i go 3/4 to full throttle .
The car runs great other wise and there are no typical signs of a problem .
A/f is 12.750ish right up to the time the car does this .
When the car backfires it stops the logging and the car shuts off and stumbles from 5400 down to 4000 rpms then trys to catchback up to itself but cant .
Im at a total loss here and will try anything i can to get over this issue .
HELP ! ! !
Racer
Joined: Aug 2005
Posts: 335
Likes: 1
hey russ, sounds like the cam timing might be a tooth off... also check for chassis/block gounds as well. are you logging any codes? also check for proper baro and map reading on datalogger as these can cause a lean misfire- seen it hundreds of times as i can see on your graph one thing i notice on your graph is that your short term fuel trim is off the chart. it should be no more than +/- 3.00%...
btw, when are we all gonna take a trip back down to monz?
btw, when are we all gonna take a trip back down to monz?
Last edited by Blowndave; Oct 24, 2008 at 11:47 PM.
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 1,158
Likes: 6
From: Winter Springs Fla
Thread Starter
Burning Brakes
Joined: Jan 2004
Posts: 1,158
Likes: 6
From: Winter Springs Fla
Always check the reluctor wheel even tho you have a brand new motor before putting everything together :/
Someone had dropped either the crank or the wheel when the motor was being built.
Lucky for me i was able to straighten it out and clean up the burrs .
Hopefully everything is in good working order now .
Someone had dropped either the crank or the wheel when the motor was being built.
Lucky for me i was able to straighten it out and clean up the burrs .
Hopefully everything is in good working order now .
