backifire under boost

[chris_mile]

Iknow it sounds silly but what are some common causes for backfiring? i was on I-94 doing 70 and gave it some gas chip and wastegate set to 15lbs. of boost on 93 octane. right when i build boost i get a huge pop and you can feel the loss of power however its not setting of the knock detector and i know the sensor works. any ideas? 1 more thing it threw a 42 on scanmaster saying electronic spark timing module bad or unplugged after the pop and it keeps coming back. the check engine light came on but after restart disappeared.

 

[The Darkside]

Sounds like it could be the ignition module or coil pack going bad.....

maybe a loose intercooler hose.....

or the positive battery cable is coming into contact with the passenger side exhaust header...This happened to me & it threw a code 42...

 

[chris_mile]

thanks ill check the batt tonight if not aggressive performance is like a 20 min. drive foor me in the D.

 

[87buickracer]

Iknow it sounds silly but what are some common causes for backfiring? i was on I-94 doing 70 and gave it some gas chip and wastegate set to 15lbs. of boost on 93 octane. right when i build boost i get a huge pop and you can feel the loss of power however its not setting of the knock detector and i know the sensor works. any ideas? 1 more thing it threw a 42 on scanmaster saying electronic spark timing module bad or unplugged after the pop and it keeps coming back. the check engine light came on but after restart disappeared.

also make sure your not loosing any fuel pressure under boost..

 

[ronbuick]

bad cam, lets hope not!!

Ron

 

[ronbuick]

What did you find out?? on your backfire, get it fixed yet

 

[chris_mile]

funny thing is after my rebuild ive felt slower and yet i should be making 100+ HP im gonna chase the electric codes first and prob. pull the motor and rebuild again. my rear main is blownout anyway.

 

[Whut]

Check the plugs? I could run all day first-second-third and in the 1/8th no problems. The car would feel solid and strong. Get it to a quarter mile track though and things would change for the worse. Same deal, get under boost and stretch it out and POP. I have been chasing a fuel related issue (read that, I have been getting better at tuning my own fast setup) and found two blow torched plugs. That stopped the backfire for me.

 

[GW2]

Dont even check the plugs just change them all! its cheap and it saved my car having similar problems. new plugs never hurt anything.

 

[chris_mile]

ok well havent got to the plugs yet but my cam sensor cap was loose and bounceing everywhere! cant believe it ran like that. fixed it and everything was great 4 a couple days of driving but this morning was going to college and at 14 psi and 45 mph it backfired with great intensity and 2 black clouds of smoke from my exhaust. no retard was detected or SES light. any Ideas???

 

[GW2]

PLUGS!!!! change them! its cheap and it may just fix your problem.

 

[Whut]

Yeah, just change the plugs. Also, you might as well order a new cam sensor while you are at it.

 

[DMan]

Are you using DirectScan?

 

[chris_mile]

no direct scan just scan master im thinking of upgrading to something recordable since i have so many tuning issues all the time. doesnt matter though ive decided to drive it til oct. then im rebuilding again after only 4K on the motor. did a dye test and im laeking oil from every imaginable location.