backfire?

[bl1tzk1213g]

everytime i shift or just press on the gass pass 3.5-4K rpm i hear popping sound. I dont feel any jerk or whatsoever. My cousin drove my car and i followed him with his lancer and when he shifts i saw smoke puff comming out from the muffler. i cant remember what color it was, it was 2 weeks ago. little dark if i remember. my car is stock except for SSQV and BCS mod. haven't installed boost controller, no pod yet. is this bad or what?

[DragonofBC]

What kind of gas are you using? I remember the only time my car backfired was when I put in 89 from a non-branded gas station (you can all take turns slapping my wrist for my sin).

[bl1tzk1213g]

91. i used to use 87! lol kill me if u like. well most of the times Vons/Albertsons/Costco 91 with my parents card lol.

it only backfires when i let go of the gas all the way. If i let go of the gas slower and not all the way it doesn't do that.

[ez1286]

What are the conditions of the plugs wires? As DragonofBC said it could be bad gas.

[DragonofBC]

Good call ez. At that RPM range, you'd be boosting and bad plugs/wires would cause some problems. If you did run 87 consistently, I'm speculating it would have detrimental effects on at least the plugs. Get some NGKs and see if that clears it up.

[bl1tzk1213g]

i used to stall on near full boost. i thought it was the gas so i started using 91, (only dad wanted to use 87). didn't fix, i changed plugs with bpr7es and it fixed to the problem so i guess they're fairly new, 2 weeks my opinion. maybe wires?

[ez1286]

Could be wires, if they haven't been changed in a while. If it still occurs after new wires it may be a problem with the coils.

[bl1tzk1213g]

prolly the wires, they're old and stock. any recommendations?

[DragonofBC]

Check plug gapping first, then check the wires. You play with fire if you are boosting using 87.

[bl1tzk1213g]

no, im using 91 now. i dunno how to check or adjust gappings.

[DragonofBC]

There used to be a great sticky on gapping spark plugs...

Here is a good site that should help you out:

http://www.dsmtuners.com/forums/showthread.php?t=174130

If you didn't gap them when you put them in, I'll bet that is your problem. I didn't properly gap mine when I got them and my car did all sorts of funky stuff.

[ez1286]

So are you saying you put the plugs in without gapping them? If so you need to pull them out and gap them (i would suggest getting Haynes repair manual goes over little stuff like gapping plugs) This could be causing the problem. New wires aren't a bad idea either.

[bl1tzk1213g]

Cool thanks. imma go to autozone tomorrow. Btw, my friend has a gst and its somewhat modded except turbo and hes got a dp and test pipe and vents to atmo and he gets backfires with flames. That normal with test pipe and venting? my other friend thought it was because my car is turbo.

[DragonofBC]

Improper venting is bad, backfiring is bad, and fire is bad. Improper venting is a one-way ticket to dead turbo/motor/car/wallet.

[BoostedSpyder]

you need to recirc your BOV. i'm pretty sure there is a kit for that one, you just need to find it. you are running rich in between shifts and that is the smoke/backfire.

and this is basic DSM knowledge... you guy's need to search a bit more.

when the BOV pings it is blowing air that has already been 'counted' back into the intake, after the MAS. when you vent it, the engine thinks there is more air in there than is really there, so it feeds fuel in accordingly. you run rich and you end up smoking a bit and backfireing a bit. i had stories of 2 foot flames comming out the back of my car when i was venting and i shouldn't have been.

it's a small price to pay for the BOV sound, so if you can stand it, keep rocking. but if you don't like to draw attention to yourself as the guy with the cool car that backfires and must be running like crap because it is smoking... keep on rocking. and you are going to foul your plugs too. so check them very soon...