popping and backfiring out of exhaust

[mtlman22]

i am having issues all the sudden on backfiring and popping out of the exhaust on decel and sometimes on a hard launch and its getting worse. anyone have any good suggestions?

 

[OL' WHITEY]

I had a similar situation and it turned out to be a rotten/broken vacuum hose on the underside of my upper intake. You may have to pull the upper to get to it. Poke around some and see if you see hear or feel anything.

Dave

 

[Modular2v]

popping on decel is pretty normal

 

[310stanger]

I had a similar situation and it turned out to be a rotten/broken vacuum hose on the underside of my upper intake. You may have to pull the upper to get to it. Poke around some and see if you see hear or feel anything.

Dave

found this same problem when i went to do my valvesprings. the oil ruins the hoses or in my case the cap. i had a weird hissing sound for a lil while and the car jus didnt run good anymore. no popping though. jus running really rich.

 

[mtlman22]

well all the intake hoses and lines are all new and prior to the car running like crap i was having an issue with it bogging out and backfiring on accel only and i did notice the AFG went way lean when it happens. it sounds like to me like it has a dead cyl?

 

[jrichker]

Do the basics first...

Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.

Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great.

See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html

IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.

Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.

Wal-Mart may now have the LCD display scanner for less than $35

 

[mtlman22]

i have no codes present

 

[v8only]

my popping was solved with a spark plug change

 

[billison]

i had the same problem and it changed when i changed the dizzy

 

[Swede958]

I have the same thing going on, bugs the heck outta me. I'm gonna check my vacuum lines again. Plugs didn't solve mine, I'd run regular, side gapped, and regular + MSD and no change...

 

[LtDavis]

I just started having almost the same exact problem within the last week. Mine seems to pop and backfire mostly at partial or half throttle on acceleration, if I give it a lot of gas it doesn't seem to do it as much. Once the engine warms up it doesn't do it nearly as bad or as much.

My autolite 25's are not more than a year old and I just installed the "Screamin' Demon" coil from Performance Distributors yesterday but it's been popping/backfiring a little before that. Two weeks ago I had my timing advanced to about 12 or 13 degrees (can't remember which he said it was) and I've been running 93 octane for a long time.

I haven't closely checked the vacuum lines yet and I haven't had time to use my nifty scanner from midway auto supply yet but I've been thinking a valve was sticking but I'll wait to see what the scanner says.

 

[postalbunny]

plugs

Had the same problem after I put long tubes in, turns out i put plugs 1 & 2 on backwards... check and make sure you didn't do the same.

 

[mtlman22]

well all the vacume lines are good the plugs have 600mi on them and so does mostly everything else. it basiclly runs like it has a crossed over wire but it doesnt it just started doing it all the sudden one day. i wonder if it might have anything to with the MSD box when i was welding in the cage? but i cant remember if i put the cage in before or after the Box

 

[mtlman22]

any other good thoughts?

 

[gt1986]

i had that same issue mostly on the decel it ended up being an exhaust leak between the my new headers and x pipe being as wise as i am i left the new nuts on the headers studs and attached with the old ones. done any exhaust work lately?

 

[mtlman22]

yea it has a whole new system on it, but those bolts are tight cause ive always had a problem with them backing out. when the popping and backfiring happens the car usually falls on its face and my A.F.G goes way lean

 

[just4bob50]

I am having the same issue also right now, but I believe it is from my new Crane HI-6 ign. and MSD dist. I was running stock dist. and an inductive ign. My starts poping below 2500 rpms, but I think the new ignition is burning up the fuel better because of the multiple sparks at low rpms now.

 

[AZNEAL311]

Will the vaccum line under intake manifold also cause a ticking if it cracked or disconected? I am having almost the same symptoms only i have a TICK, sounds like it is coming from under the upper intake manifold but doesnt sound like it is internal as in lifter or valve.Any Ideas?

 

[mtlman22]

Wow! it seems alot of people are having the same problem. i might very well be the MSD setup i have in there but i find it very hard to believe. ive tryed a few things and still havent found the problem?

 

[LtDavis]

I don't have the MSD and mine is still doing it though. Its been over 2 weeks since I advanced my timing and it just started this popping about 3 days ago. I checked the distributor to see if it was loose, its not. After I installed the Screamin Demon coil it still did it, only other ignition mods are FRPP wires and the plugs are only a year old.

I checked all the vacuum lines I could see and none seem cracked. I pulled codes and got 67 which is some kind of clutch switch failure I think, and 33 which is EGR valve not opening properly... could that be the problem? The car has 120,000 miles and really only the last 3000 have been hard (dragstrip twice and some street racing)