Backfiring

chuck88 · 04-02-2003, 05:35 PM

I have an 88GT (speed density) GT 40 upper lower (Lower is ported) I have been told that I may have to much intake for stock heads.

My question The car backfires between 2000 & 2500 rpm when you push the pedal down semi hard (ok at wide open throttle)

what could cause this?

I am thinking of going heads, cam, & mass air conversion in the near furture would this cure the backfiring?

Thanks in advance

Chuck88

Hethj7 · 04-02-2003, 07:53 PM

My car had a backfiring problem for while. I found out I had a bad fuel injector. It wasn't flowing what it should and was essentially leaning out that cyclinder.
I replaced all 8 of them and haven't had a problem since.

When I had this problem a Ford dealer pulled the codes for me and did a flow test on the injectors. They just charged me for an hour of labor, which I didn't think was too bad at dealership.

cyberstang5.0 · 04-03-2003, 08:11 AM

Also, double check your timing. That can cause you to backfire.

james87gt · 04-03-2003, 09:16 AM

check for vacuum leaks, timing, fuel pressure and also read your spark plugs

SilverSN95 · 04-03-2003, 06:54 PM

From what I understand a backfire is when you get combustion happening in the intake instead of the combustion chamber as intended. I thought there was only a few reasons for this to happen. First would be the timing of the valve positions and/or spark not matching the fuel injector firing. The other would be an extreme rich condition in the manifold such as when an injector is stuck open. Add a little spark and boom!!

Maybe a complete tune-up would help?

Hethj7 · 04-03-2003, 07:26 PM

SilverSN95- That is a good point. My problem was a popping sound, probably not as loud as you would think a backfire would be, but still very audible. Sorry if this confused anyone.

drtbiker · 04-03-2003, 08:46 PM

sounds like timing to me, my car did the same thing and i advanced the timing a little more and it was fine
later
raini

94snake · 04-05-2003, 12:05 PM

You should check your spark plugs. My 94 cobra had a similier problem, it would backfire betweem 2500 and 3500 rpm's. it was a bad spark plug that was grounding out on the header!

04-02-2003, 05:35 PM	#1
chuck88 Registered Member Join Date: May 1999 Location: Wood Ridge NJ USA Posts: 341	Backfiring I have an 88GT (speed density) GT 40 upper lower (Lower is ported) I have been told that I may have to much intake for stock heads. My question The car backfires between 2000 & 2500 rpm when you push the pedal down semi hard (ok at wide open throttle) what could cause this? I am thinking of going heads, cam, & mass air conversion in the near furture would this cure the backfiring? Thanks in advance Chuck88 __________________ So what if its "midlife crisis". Wife, 2 kids, busy job, "fixer upper" house, and I still have time for the Mustang!!! I Love my kids!!!

04-02-2003, 07:53 PM	#2
Hethj7 Mizzou Tigers Join Date: Apr 1999 Location: weston, MO United States Posts: 1,455	My car had a backfiring problem for while. I found out I had a bad fuel injector. It wasn't flowing what it should and was essentially leaning out that cyclinder. I replaced all 8 of them and haven't had a problem since. When I had this problem a Ford dealer pulled the codes for me and did a flow test on the injectors. They just charged me for an hour of labor, which I didn't think was too bad at dealership. __________________ 2006 Mustang GT 1990 LX GT-40 motor 262 horsepower, 307ft-lbs (sold but forever loved) 1998 Contour SVT Rice Haters Club Member #244

04-03-2003, 07:26 PM	#6
Hethj7 Mizzou Tigers Join Date: Apr 1999 Location: weston, MO United States Posts: 1,455	SilverSN95- That is a good point. My problem was a popping sound, probably not as loud as you would think a backfire would be, but still very audible. Sorry if this confused anyone. __________________ 2006 Mustang GT 1990 LX GT-40 motor 262 horsepower, 307ft-lbs (sold but forever loved) 1998 Contour SVT Rice Haters Club Member #244

04-03-2003, 08:46 PM	#7
drtbiker Registered Member Join Date: Jan 2002 Location: Mt. Prospect,IL Posts: 474	sounds like timing to me, my car did the same thing and i advanced the timing a little more and it was fine later raini __________________ 87-ford-mustang-SOLD! mods: 3:73's, off road h-pipe, b303 cam in gt- 40 motor w/ Power Plus intake, edelbrock 70mm tb & egr spacer, 72mm C&L, bbk long tubes, tremec tranny, centerforce dual friction clutch, upr and lwr CA's 255lph FP and soon more to come.... when i have money again SOME ADVICE Don't do burn outs in reverse it is very expensive New times with dead hook on dr's 13.27@103 with 2.0 60 foots w/100lb system Fastest time to date: 12.8@113

04-05-2003, 12:05 PM	#8
94snake Registered Member Join Date: Nov 2002 Location: Panama City Fl. Posts: 152	Backfiring You should check your spark plugs. My 94 cobra had a similier problem, it would backfire betweem 2500 and 3500 rpm's. it was a bad spark plug that was grounding out on the header!

04-03-2003, 08:11 AM	#3
cyberstang5.0 347ci of HORSE POWER!!! Join Date: Jul 2001 Location: Houston, TX Posts: 1,416	Also, double check your timing. That can cause you to backfire.

04-03-2003, 09:16 AM	#4
james87gt Registered Member Join Date: Jan 2002 Posts: 62	check for vacuum leaks, timing, fuel pressure and also read your spark plugs

04-03-2003, 06:54 PM	#5
SilverSN95 Registered Member Join Date: May 2002 Location: Ontario Posts: 39	From what I understand a backfire is when you get combustion happening in the intake instead of the combustion chamber as intended. I thought there was only a few reasons for this to happen. First would be the timing of the valve positions and/or spark not matching the fuel injector firing. The other would be an extreme rich condition in the manifold such as when an injector is stuck open. Add a little spark and boom!! Maybe a complete tune-up would help?

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