Car backfires when shifting.

gt-351 · Sep 21, 2005

The car backfires when I powershift or speed shift at high rpm. I have played alittle with fp & timing. I have made no changes sence the car was tuned. I run mac exhaust with a prochamber dumped 2 1/2".

mo_dingo · Sep 21, 2005

do you mean a backfire or some exhaust crackling? Because if you are backfiring, you have a timing problem, or maybe an a/f ratio problem...

Try cleaning your maf and IAT sensor and see what happens.....

And stop powershifting, what the heck is wrong with you? Do you want a blown transmission???? T-5's don't take much abuse.....sorry, just my opinion on the matter.
Scott

CManT1914 · Sep 21, 2005

Popping is normal, backfiring (the REAL LOUD bang) means you're running too rich generally. Pull your plugs and see what they look like. Like Scott said, you might try cleaning some sensors too.

gt-351 · Sep 27, 2005

Just making sure the IAT sensor is screwed into my cold air intake right? That was cleaned & the mass air meter. Ith IAT was pretty dirty. Hard to tell on the mass air. I cleaned both with a q-tip.

CManT1914 · Sep 27, 2005

gt-351 said:
Just making sure the IAT sensor is screwed into my cold air intake right? That was cleaned & the mass air meter. Ith IAT was pretty dirty. Hard to tell on the mass air. I cleaned both with a q-tip.

Yea IAT is threaded into the intake pipe (cold air kit). Make sure it's indexed to where the actual sensor is broadside to the incoming air.

HISSIN50 · Sep 28, 2005

If you dont run cats, that can help unmuffle the backfire.

That with dumps might do it.

Good luck.

mytight95 · Sep 28, 2005

Couldn't a vacuum leak be another reason for it to backfire... at higher rpms... when vac. is usually higher....

jason

Zero Signal · Sep 28, 2005

You guys are confusing what the IAT is. Scott isn't talking about the ACT which is what is screwed into the pipe.

I got a mean backfire the other day while shifting at 4k while the motor was in startup mode. Scott. . . Once we get our stuff going, we definitely need that PLX unit!

95Vert · Sep 28, 2005

Check your timing. I had backfire and messing with it was the solution.

HISSIN50 · Sep 28, 2005

Zero Signal said:
You guys are confusing what the IAT is. Scott isn't talking about the ACT which is what is screwed into the pipe.

Huh? John, It seemed to me that he did mean the IAT (Intake Air Temp sensor - I dont know what else the acronym can mean). ACT does = IAT.

CManT1914 · Sep 28, 2005

Zero Signal said:
You guys are confusing what the IAT is. Scott isn't talking about the ACT which is what is screwed into the pipe.

Then what is he talking about? Like JT said, IAT = ACT, same thing. I hope you're not confusing it with the IAC, which would have nothing to do with his backfiring problem.

Zero Signal · Sep 28, 2005

ACT Air Charge Temp., same thing then. I'm just used to ACT. Yeah not the idle air control.

robertdale · Sep 28, 2005

If you are not running cats and still have the smog pump hooked up that is the problem. Mine would pop a little when I shifted and if I shifted hard it would be worse. I removed the smog pump and that fixed it.

gt-351 · Sep 28, 2005

no cats,Im on my way to the dyno to ck my a/f raito & play with timing & fp. I'll also ck for vac leaks. But I did clean the RIGHT senors right???

CManT1914 · Sep 28, 2005

gt-351 said:
no cats,Im on my way to the dyno to ck my a/f raito & play with timing & fp. I'll also ck for vac leaks. But I did clean the RIGHT senors right???

CManT1914 said:
Yea IAT is threaded into the intake pipe (cold air kit). Make sure it's indexed to where the actual sensor is broadside to the incoming air.

If you're still asking about the IAT sensor, yea, you got the right one.

HISSIN50 · Sep 28, 2005

I am curious about something said, as it never occured to me that anyone would do it. If one has no cats and the smog pump hooked up, what did the person do? Just leave the diverter tube dangling next to the H-pipe?

Mustang95GTS · Sep 28, 2005

I had this condition also, it was because of my coil for some reason. Check into that first.

Sean

90bronconate · Sep 29, 2005

HISSIN50 said:
I am curious about something said, as it never occured to me that anyone would do it. If one has no cats and the smog pump hooked up, what did the person do? Just leave the diverter tube dangling next to the H-pipe?

hmm. curious as well. and why would it the exhaust pop? what exactly is happening to make it pop?

CManT1914 · Sep 29, 2005

HISSIN50 said:
I am curious about something said, as it never occured to me that anyone would do it. If one has no cats and the smog pump hooked up, what did the person do? Just leave the diverter tube dangling next to the H-pipe?

JT, aftermarket mid-pipes without cats, still have a hookup for the smog tube. I actually hooked my smog tube up to the h-pipe, although it just blew air through. Now since I don't have smog, I capped off the pipe on the h-pipe.

HISSIN50 · Sep 29, 2005

CManT1914 said:
JT, aftermarket mid-pipes without cats, still have a hookup for the smog tube. I actually hooked my smog tube up to the h-pipe, although it just blew air through. Now since I don't have smog, I capped off the pipe on the h-pipe.

Wow, I learn something every day. I would have never guessed that a non-catted pipe would have a hook up for the smog heffer. That is kind of like tits on a bull.

Thanks Chris - now this all makes more sense.

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