backfire under load please help!!
backfire under load please help!! car will sit and ilde fine all day long once you put it under load it backfires by backfire I mean a loud pop out the exhaust . Its very random it might do it once in a minute or 5 times . Just about everything on the car is new . Everthing listed is new : Opti,ICM,coil,plugs,wires,fuel filter, . The fuel pressure stays around 35 may go up to 38 or 39 but falls no less than 35 psi. I was gonna change the fuel pump but not sure if its the problem . Not showing service engine light or any codes on the scanmaster. Im not sure what to do ive triple checked everthing . Someone told me could be a stuck valve and to double check the valves. Everyones imput is greatly apreciated
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you can get a long screw driver and put the tip to the valve cover when running right over where each rocker is and then put your ear to the handle of the screw driver and you can listen to the motor like that and get a decent idea or you could pull your covers and watch the motor run.
hows your o2's? maybe your coolant sensor? ive heard it can make your car run funky but all this sensor **** to lt1s is new to me seeing im a carb an points person..
hows your o2's? maybe your coolant sensor? ive heard it can make your car run funky but all this sensor **** to lt1s is new to me seeing im a carb an points person..
any one else have an idea. I checked the fuel pressure with the vaccuum of the regulator it was 39 psi with no fuel in the vaccuum line when I hooked it back up it went to 35 psi just not sure what direction to go .
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Joined: Apr 2007
Posts: 420
Likes: 0
From: Kempner, TX
Check the most obvious, basic stuff first.
I'd first verify the spark plug routing. Two cross wires; one wire arcing to another, arcing to ground, etc.
Yea, I know, whenever I recommend that, I get responses "I've checked the plug route "X" number of times, etc" Look again and try using "better eyes". Many guys have found something as simple as that as the cause.
One or more lifter preload settings too tight is another one. Bent pushrod, broken valve spring, something else in the valve train.
There are a LOT more things to check, but get back to us once you've verified the above. Throwing more parts at the problem "ain't" gonna get it done.
Jake
I'd first verify the spark plug routing. Two cross wires; one wire arcing to another, arcing to ground, etc.
Yea, I know, whenever I recommend that, I get responses "I've checked the plug route "X" number of times, etc" Look again and try using "better eyes". Many guys have found something as simple as that as the cause.
One or more lifter preload settings too tight is another one. Bent pushrod, broken valve spring, something else in the valve train.
There are a LOT more things to check, but get back to us once you've verified the above. Throwing more parts at the problem "ain't" gonna get it done.
Jake
car will sit and ilde fine all day long once you put it under load it backfires by backfire I mean a loud pop out the exhaust . Its very random it might do it once in a minute or 5 times . Just about everything on the car is new . Everthing listed is new : Opti,ICM,coil,plugs,wires,fuel filter, . The fuel pressure stays around 35 may go up to 38 or 39 but falls no less than 35 psi. I was gonna change the fuel pump but not sure if its the problem . Not showing service engine light or any codes on the scanmaster. Im not sure what to do ive triple checked everthing . Someone told me could be a stuck valve and to double check the valves. Everyones imput is greatly apreciated
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What is fuel pressure when vacum line is off fuel pressure regulator?
Datamaster will allow you to see what is going on some scanners are good others won't tell you other than a code. Datamaster will allow you to collect data and send it to others and get many eyes looking at it.
I can guess as good as anyone but seems you have listen to many guesses already...post the file once you get the cable.
Good luck
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First of all I really apreciate the help. im kinda nearing the end with this car . I just changed the opti it has no miles on it .Ive though about tearing it back off and rechecking the opti itself . First im gonna recheck the wires on the opti . I was wondering if any tunning software would help with monitoring what the motor is doing
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