I know it's been asked before but...this one was bad

[Roland69]

I was driving my car kinda hard (not that hard) and I was shifting at around 4500 and I let off once I got near the top of 4th gear.....when I let of I got a nice big BANG so I looked in my rearview and there was a still cloud of smoke ...kinda looked like when you set off a fire-cracker and you get that still cloud of smoke.

what could that of been it's been doing it alot lately and mostly when I shift from 2nd to 3rd in the 4K range but I don't think it matters much what gear I'm in or going to.

Any thoughts

 

[srothfuss]

It's hard to tell what a puff of smoke is.. What color was it? That might narrow some things down.

A guess: The bang / smoke is from your clutch.

 

[Strype]

Has the car had a tune up lately? Does it have the stock intake?

 

[HISSIN50]

I let off once I got near the top of 4th gear.....when I let of I got a nice big BANG

When you let off at high RPM's you shut off the engine's supply of air, even though it's still pumping at high RPM's. It sounds like you simply had a rich backfire.

Does your IAC work decently? There is a dashpot function in the puter programming for no throttle deceleration and it requires a decently functional IAC.

Otherwise, you might simply be running a hair rich.

Random thoughts. Good luck bud.

 

[Busted07]

Otherwise, you might simply be running a hair rich.



I would lean towards this also

 

[Roland69]

yes it is the stock intake and no tune up lately...HISSIN I think what you said is the problem it does run a bit rich in the upper RPM's and it has a back fire burbble when I let of the gas and let the engine brake for me...But when I rod it and let off it gives one big bang (not everytime) and this was the firse time I seen smoke left from the back fire.

Should I try cleaning the IAC and will I need a new gasket for it. I don't want to take it off and have to walk to the parts store lol

 

[s&k stangs]

Should I try cleaning the IAC and will I need a new gasket for it. I don't want to take it off and have to walk to the parts store lol

The gasket on the IAC is pretty stiff. I just took mine off for cleaning recently and the gasket popped right off. You shouldnt have a problem unless sealant was used last time it was put back on. You may want to get one before you remove the IAC just in case. you can always return it or keep it as a spare.

 

[Roland69]

I don't think the IAC has ever been off

 

[s&k stangs]

I don't think the IAC has ever been off

we,, I don't know what the protocol for installing the gasket is, but when I took mine off, there was no evidence of any sealant on the IAC or TB side, Also check your PCV valve. MY car was having similar problems not too long ago.rough surgy idle(from 500 to 1100 was not uncommon, chugged and lurched under throttle, and would sometimes stall out for no reaon while i was driving). When I took the IAC off, oil was literally dripping out of it, and the gasket was covered and it was all in the throttle body opening as well. I sprayed everything out with intake cleaner(make sure you use a teflon friendly throttle body or intake cleaner when spraying it into the throttle bodyand even sprayed some into the intake. After seeing all the oil, I replaced the PCV valve and the screen filter underneath it.i then reset the idle and adjusted the tps which was reading 1.7 volts(key on engine off)back to .99v. I also replaced the fuel filter just to be sure. The car runs better than it has in a very long time. almost like new, but its runnong a little rich, so I may need to address the timing. Hope this helps

 

[Roland69]

thanks for the tip's..I want to give her a tune up here soon.

 

[3 eyed snake]

mans thats explaining alot bout my 90GT. i ought to try some of that stuff out. its good to have people that knkow what the hells going on... thanx

 

[HISSIN50]

The PCV side of things is one reason why some folks like using an air/oil separator in the PCV.

 

[Roland69]

and they look cool lol

 

[DMAN302]

Tune up Timmeh..pull the TB and IAC and give em hell with some carb cleaner, replace plugs,wires,filters..if it's been a while it will help you out quite nicely. Don't give the backfire a second thought unless it becomes a common occurence.