JIM73240Z Posted October 20, 2008 Share Posted October 20, 2008 just started on friday. start the car up and it sounds like it is muffled too much like there is a bannana in the exhaust. then after 30 sec or so it clears up like normal. drive around and then it sounds like fire crakers or m-80s are in the back of the car. pop. pop. this goes for 30 sec or so. no noticable difference between easy throttle or harder throttle. after it is done, i can hot rod it around or grand mother it for the rest of the trip. wtf. the temp has gone down here in the phx area. like mid 60's for the lows. ????? any ideas. jimbo Quote Link to comment Share on other sites More sharing options...
woldson Posted October 20, 2008 Share Posted October 20, 2008 Do you have a cat on the car? Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted October 20, 2008 Author Share Posted October 20, 2008 nope. tuned header, 2 1/2" pipe with a 36" glass pack. been like that for 3-4 months. just started doing it with no changes that i made. ???? jimbo Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 20, 2008 Share Posted October 20, 2008 Cooler Air, denser, possibly has gotten your exhaust to a point where it was too rich to combust spontaneously before now is juuuust right? Free flow exhausts will backfire if there is enough fuel in them, and enough aspirated air... Put a shot of Propane in a gallon paint can, poke a hole in one end, and light the hole. Thing burns out the hole for a second, then 'goes out' only to BLAM! Fire off several seconds after the visible flame went inside the can. You go from a combustible mixuure, to an explosive mixture, and the burn rate accelerates, giving the loud bangs. Same thing in your exhaust. I'd say you are leaner now instead of really rich out the tailpipe, and it's more combustible for a little while till everything gets up to operational temperature. Vague post, but that it goes away leads me in that direction. A bad condenser on the points can do something similar giving a backfire out the exhaust, but it won't go away with the car warming up...same for incorrect firing order or plug wires crossfiring, etc... Those stay... Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted October 20, 2008 Author Share Posted October 20, 2008 thanks tony. it happend also when the temp was in the 80's. the exhaust reeks of gas too. i went out this morning and stood by the pipe and held a piece of paper behind the pipe and it was getting black from the exhaust. maybe running too lean. idk. jimbo Quote Link to comment Share on other sites More sharing options...
JSM Posted October 20, 2008 Share Posted October 20, 2008 If it's black your running to rich, not lean. I'd check your plugs first. Likely they are fowled causing the issue your having because it's not getting burned. I'm assuming carbs??? Quote Link to comment Share on other sites More sharing options...
JIM73240Z Posted October 20, 2008 Author Share Posted October 20, 2008 nope. 76 280 with fi. will check the plugs when i get home. jimbo Quote Link to comment Share on other sites More sharing options...
JSM Posted October 21, 2008 Share Posted October 21, 2008 So what was the outcome? If the plugs are fowled it may only relate to your issue. You will still have to sort out why your running rich. Quote Link to comment Share on other sites More sharing options...
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