backfiring

srv1 · 09-03-2001, 11:52 AM

has this happened to you? i was giving my friend a ride yesterday, and i was haulin' threw the gears on the highway, and all of the sudden, POP! backfired out of the exhaust! this is the second time it did it! runnin' 13 degrees, new O2's, and stock everything, except for a complete exhaust system. oh this all seem to start when i put the MAC shorties on. any suggestions?

Topless In Texas · 09-03-2001, 12:48 PM

Hey SRV!

The same thing happened to me last week. Topless was running kind of ragged, and then she started backfiring. NOt loud but little pops, just during regular driving.(enough to be embarassing!)

Turns out My O2 sensors were wasted. She's running great now.
Mike hooked her up to the tester and she threw the codes. Sure made it easier testing it that way instead of starting to replace crap thats not necessary! Good luck, I'd get it tested if you can. Ive got MAC shorties on mine too, but never a problem...Maybe someone has an opinion??? Seeya! Topless

------------------
1994 GT CONVERTIBLE
TOPLESS IN TEXAS Girls can too's July "Mare of the Month"

Performance Red. Cold Air Ind.,K&N,H.P. Pulleys,OffRoad H-Pipe,Subframe Connectors,Flows,3.55,Light bar,Custom HeadRests.Lotta Chrome

PKRWUD · 09-03-2001, 09:53 PM

When, specifically, did it backfire? Where you accelerating, cruising, or had you just let off the gas?

Have you checked for codes?

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

srv1 · 09-03-2001, 10:49 PM

hey Topless! no mine is running great. i dont know what it is. no codes though. i hooked it up to my scanner and nothing.

pkrwud. it happened when i was at WOT climbing up in speed and RPM. around 4500 i believe. it didnt hesitate or anything. just popped! i think it has to do with the exaust system. velocity went down with the overall bigger pipes, so im thinking that the exaust gases is running real high on the HC side. i know its supposed to at WOT, but i think all the HC's are sitting in the muffler and then getting ignited when it hits a certain temperature. thats just an educated guess. give me your input.

PKRWUD · 09-04-2001, 12:13 PM

Do you have cats in your new exhaust?

srv1 · 09-04-2001, 05:27 PM

no Cats.

PKRWUD · 09-04-2001, 08:20 PM

Hard to say. Almost sounds like it's floating a valve, but I reall need to see it. Traditionally, a backfire like that happens the split second after you release the throttle, or start to, and is usually caused by a hole or an opening along the pipes (usually where the pipes bolt to the headers). What happens is: when you are in the throttle, and suddenly back off, even just a little bit, you create a vacuum. This applies to the exhaust, too. The vacuum pulls oxygen rich air into a very hot spot in the exhaust, and it ignites.

If that's not your case, then you probably don't have enough back pressure.

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

srv1 · 09-04-2001, 11:03 PM

well i was on the throttle and the valves werent floatin' at 4500. i think your right, backpressure/velocity are the keys to my backfiring i think. yeah i know the concept if the backfiring when you let off the gas. for know, i will just live with it. besideds it doesnt happen all the time. thanks.

09-03-2001, 11:52 AM	#1
srv1 Get down..... Join Date: Apr 2001 Location: Room 103 Posts: 2,095	backfiring has this happened to you? i was giving my friend a ride yesterday, and i was haulin' threw the gears on the highway, and all of the sudden, POP! backfired out of the exhaust! this is the second time it did it! runnin' 13 degrees, new O2's, and stock everything, except for a complete exhaust system. oh this all seem to start when i put the MAC shorties on. any suggestions?

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Help! Backfiring and loss of power	spuckie	Blue Oval Lounge	1	11-24-2003 01:08 AM
Help! Backfiring and loss of power	spuckie	Windsor Power	1	11-21-2003 07:40 PM
Backfiring Problems!	MITCHL	Windsor Power	5	11-21-2002 01:52 PM
Backfiring on deceleration fixed !!!!	70 Pony	Classic Mustangs	2	09-01-2000 08:37 AM
Backfiring on Deceleration...	Idhomustang	Classic Mustangs	12	08-31-2000 01:59 AM

09-03-2001, 12:48 PM	#2
Topless In Texas Not broken anymore! Join Date: May 2001 Location: La Porte, TEXASS :) Posts: 1,963	Hey SRV! The same thing happened to me last week. Topless was running kind of ragged, and then she started backfiring. NOt loud but little pops, just during regular driving.(enough to be embarassing!) Turns out My O2 sensors were wasted. She's running great now. Mike hooked her up to the tester and she threw the codes. Sure made it easier testing it that way instead of starting to replace crap thats not necessary! Good luck, I'd get it tested if you can. Ive got MAC shorties on mine too, but never a problem...Maybe someone has an opinion??? Seeya! Topless ------------------ 1994 GT CONVERTIBLE TOPLESS IN TEXAS Girls can too's July "Mare of the Month" Performance Red. Cold Air Ind.,K&N,H.P. Pulleys,OffRoad H-Pipe,Subframe Connectors,Flows,3.55,Light bar,Custom HeadRests.Lotta Chrome

09-03-2001, 09:53 PM	#3
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	When, specifically, did it backfire? Where you accelerating, cruising, or had you just let off the gas? Have you checked for codes? Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

09-03-2001, 10:49 PM	#4
srv1 Get down..... Join Date: Apr 2001 Location: Room 103 Posts: 2,095	hey Topless! no mine is running great. i dont know what it is. no codes though. i hooked it up to my scanner and nothing. pkrwud. it happened when i was at WOT climbing up in speed and RPM. around 4500 i believe. it didnt hesitate or anything. just popped! i think it has to do with the exaust system. velocity went down with the overall bigger pipes, so im thinking that the exaust gases is running real high on the HC side. i know its supposed to at WOT, but i think all the HC's are sitting in the muffler and then getting ignited when it hits a certain temperature. thats just an educated guess. give me your input.

09-04-2001, 12:13 PM	#5
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Do you have cats in your new exhaust?

09-04-2001, 05:27 PM	#6
srv1 Get down..... Join Date: Apr 2001 Location: Room 103 Posts: 2,095	no Cats.

09-04-2001, 08:20 PM	#7
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Hard to say. Almost sounds like it's floating a valve, but I reall need to see it. Traditionally, a backfire like that happens the split second after you release the throttle, or start to, and is usually caused by a hole or an opening along the pipes (usually where the pipes bolt to the headers). What happens is: when you are in the throttle, and suddenly back off, even just a little bit, you create a vacuum. This applies to the exhaust, too. The vacuum pulls oxygen rich air into a very hot spot in the exhaust, and it ignites. If that's not your case, then you probably don't have enough back pressure. Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

09-04-2001, 11:03 PM	#8
srv1 Get down..... Join Date: Apr 2001 Location: Room 103 Posts: 2,095	well i was on the throttle and the valves werent floatin' at 4500. i think your right, backpressure/velocity are the keys to my backfiring i think. yeah i know the concept if the backfiring when you let off the gas. for know, i will just live with it. besideds it doesnt happen all the time. thanks.