What causes a backfire? I just put on headers, H pipe, and Flowmasters on a 88GT with 46K miles (yes original) and now it it has noticably more power [sm=gears.gif]and that is good but I am seeing some issues[sm=shootshoot.gif]
1) backfires during Deceleration, especially during 2nd and 3rd gear once I put in the clutch and only when RPM's around 4500-5000. does it only once..
2) Sometimes when I come to a stop the idle will drop, normal is about 750rmp and it willdrop to like 100or all the way then pop back up to normal, and a few times the car has turned off.

I think the back fire means a lean mixture. Maybe I just need to let the computer adjust to the new sh-tuff but I am not sure about the idle and how to resolve.. have ideas?

 

i dunno... mine does it too... prob has to do w. not having cats anymore...

 

Are either of you still using the smog pump and tubes to the back of the heads?

 

if they say no is that the reason, or were you going to recco. removing them?

 

my car did that I had a bad header gasket that I was neglectin to change due to the weather after I would get off the throttle when racing or getting on it I would hear a Pop or back fire you could say .What it was is air getting sucked in threw the leak in the header gasket and "explodin once it works it way threw you exhuast system I change my leaking gasket to day and it stoped doing it all together

 

It has been known to cause the backfire on decel like the old glass packs. If you remove The cats then there is no reason to leave the smog pump or tubes. The pump is pushing air into the back of the heads causing the popping. I have experienced this personally. I deleted the smog pump and capped the heads and it went away.

 

no ****... yup mines still hooked up... will that cause some small random ones when above 4500 too?

 

4500 ....... Hell I dunno aboout that. On accel or decel?

 

accel... it doesnt do it alot, but sometimes up above there itll give me small, random back fires... its no good, lol

just changed recently all my spart stuff(cap, rotor, wires, plugs, coil) tryin to fix it, its better, but not gone

 

um. smog pumps.. are those the annoying hoses and junk that are on the passenger side that were causeing me havoc while trying to tighten my pass side header? and there is a tube that goes into the H pipe... If so then yes still hooked up? Also if so are you suggesting i take that OFF and plug the holes?i will if that will fix it but obviously want to make sure it is not causeing another problem. oh and I no longer have cats... so what is the fix? I might tighten my header bolts again maybe I do have a leak like someone suggested.... Thanks