Random backfire

shagy236 · 10-27-2009, 12:40 AM

I have noticed more now that my exhaust is free flowing that when playing on the throttle the car sometimes makes a loud backfire between shifts. It makes no difference if im shifting fast or slow. As far as I know the car is all stock. The kid I got it from knew nothing of cars and bought it with the rebuild done. I have nothing to compare mine to but it seems really fast for stock.

Ben · 10-27-2009, 03:15 AM

Is there an aftermarket blow off valve?

shagy236 · 10-27-2009, 09:28 PM

Yea it's a greddy

Ben · 10-28-2009, 11:59 AM

That could cause it

drateda.w.d · 10-28-2009, 01:09 PM

With a BOV your car runs rich between shifts because you're releasing all the metered air which in turn leave more fuel and less air in your engine.

shagy236 · 10-28-2009, 09:23 PM

wow that makes alot of sense. maybe thats why everyone says to stick with the stock one

Medusa · 10-28-2009, 09:29 PM

Definitely.

You may or may not be shooting flames out your tailpipe too. What kind of exhaust set up do you have?

shagy236 · 10-28-2009, 09:46 PM

Yea definitly flames. No real exhaust i ran a 3in pipe from turbo to back of car

Medusa · 10-29-2009, 01:11 AM

Well then you'd most definitely get flames.

There's a picture on this forum from when one of the board members was dyno testing his car, and there are 5 to 6 foot flames shooting out the back.

CJMR2T · 10-30-2009, 05:20 PM

As it was stated above an open air vented BOV will cause this. Something else to check specially if the previous owner had messed with the car any and didn't know anything about what he was doing is the TPS adjustment. The adjustment is to set the IDL switch point.
The IDL circuit tells the ecu when the throttle is fully closed. The ECU impliments a fuel cut anytime the IDL is switch is closed and the RPM is above a certian point (typically 1500RPM IIRC). This is the Decel fuel (overrun) cut to save fuel. If the ecu doesn't cut fuel like it should when in the engine is in a decel state about the certian RPM, it'll cause back firing too but usually not to bad though..... But still probably a problem in having a atmo vented BOV.

shagy236 · 11-01-2009, 03:37 PM

Cool guys thanx for the good info

10-27-2009, 12:40 AM	#1 (permalink)
shagy236 Some Skills Join Date: Oct 2009 Location: Tucson Az Posts: 77 Thanks: 0 Thanked 2 Times in 2 Posts My Google Map iTrader Rating: (0/0% )	Random backfire I have noticed more now that my exhaust is free flowing that when playing on the throttle the car sometimes makes a loud backfire between shifts. It makes no difference if im shifting fast or slow. As far as I know the car is all stock. The kid I got it from knew nothing of cars and bought it with the rebuild done. I have nothing to compare mine to but it seems really fast for stock.

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10-27-2009, 03:15 AM	#2 (permalink)
Ben Same In The End Join Date: Aug 2006 Location: Oceanside, CA / Reno, NV Posts: 4,274 Thanks: 20 Thanked 309 Times in 284 Posts My Google Map iTrader Rating: (16/100% )	Is there an aftermarket blow off valve?

10-27-2009, 09:28 PM	#3 (permalink)
shagy236 Some Skills Join Date: Oct 2009 Location: Tucson Az Posts: 77 Thanks: 0 Thanked 2 Times in 2 Posts My Google Map iTrader Rating: (0/0% )	Yea it's a greddy

10-28-2009, 11:59 AM	#4 (permalink)
Ben Same In The End Join Date: Aug 2006 Location: Oceanside, CA / Reno, NV Posts: 4,274 Thanks: 20 Thanked 309 Times in 284 Posts My Google Map iTrader Rating: (16/100% )	That could cause it

10-28-2009, 01:09 PM	#5 (permalink)
drateda.w.d Some Skills Join Date: Jul 2009 Location: Portland, Oregon Posts: 86 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (1/100% )	With a BOV your car runs rich between shifts because you're releasing all the metered air which in turn leave more fuel and less air in your engine.

10-28-2009, 09:23 PM	#6 (permalink)
shagy236 Some Skills Join Date: Oct 2009 Location: Tucson Az Posts: 77 Thanks: 0 Thanked 2 Times in 2 Posts My Google Map iTrader Rating: (0/0% )	wow that makes alot of sense. maybe thats why everyone says to stick with the stock one

10-28-2009, 09:29 PM	#7 (permalink)
Medusa HAY GUISE! Join Date: Sep 2008 Location: Reno, NV Posts: 752 Thanks: 9 Thanked 18 Times in 17 Posts iTrader Rating: (0/0% )	Definitely. You may or may not be shooting flames out your tailpipe too. What kind of exhaust set up do you have?

10-28-2009, 09:46 PM	#8 (permalink)
shagy236 Some Skills Join Date: Oct 2009 Location: Tucson Az Posts: 77 Thanks: 0 Thanked 2 Times in 2 Posts My Google Map iTrader Rating: (0/0% )	Yea definitly flames. No real exhaust i ran a 3in pipe from turbo to back of car

10-29-2009, 01:11 AM	#9 (permalink)
Medusa HAY GUISE! Join Date: Sep 2008 Location: Reno, NV Posts: 752 Thanks: 9 Thanked 18 Times in 17 Posts iTrader Rating: (0/0% )	Well then you'd most definitely get flames. There's a picture on this forum from when one of the board members was dyno testing his car, and there are 5 to 6 foot flames shooting out the back.

10-30-2009, 05:20 PM	#10 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,688 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	As it was stated above an open air vented BOV will cause this. Something else to check specially if the previous owner had messed with the car any and didn't know anything about what he was doing is the TPS adjustment. The adjustment is to set the IDL switch point. The IDL circuit tells the ecu when the throttle is fully closed. The ECU impliments a fuel cut anytime the IDL is switch is closed and the RPM is above a certian point (typically 1500RPM IIRC). This is the Decel fuel (overrun) cut to save fuel. If the ecu doesn't cut fuel like it should when in the engine is in a decel state about the certian RPM, it'll cause back firing too but usually not to bad though..... But still probably a problem in having a atmo vented BOV.

11-01-2009, 03:37 PM	#11 (permalink)
shagy236 Some Skills Join Date: Oct 2009 Location: Tucson Az Posts: 77 Thanks: 0 Thanked 2 Times in 2 Posts My Google Map iTrader Rating: (0/0% )	Cool guys thanx for the good info