Misfire at idle

[souljasmooth]

I have a 93 Typhoon that has a bad misfire. It seems like it only misfires at idle. When you start the car up in the mornings, it seems to fire fine for a few seconds, then it misfires. When I am at a stoplight, it seems to misfire way more. Is there a simple fix for this? The truck only has 75K miles. I went and got a full tune-up including spark plugs, Wires, Cap and Rotor. The old spark plugs actually looked okay. I had a compression check done, and it turned out perfect. The mechanic checked the injectors, and found one that wasnt running 100%. So I replaced them all with flow-matched injectors, and it still misfires. The mechanic was very sure that it was the one bad injector. Where should I go from here?

 

[Syclone #1721]

Re: Misfire at idle

Lower intake gasket....I had the same scenario and the intake gasket was leaking. It ran ok too but when I pulled the gasket, it was very badly blown. was a worldf of difference after replaced...just a thought.

 

[souljasmooth]

Re: Misfire at idle

I think the lower intake gasket was changed when the injectors were changed out. Unless there is another set of gaskets he changed out. Ill have to ask my mechanic tomorrow.

 

[Syclone #1721]

Re: Misfire at idle

fyi, he may changed it but for the record, the lower intake does not need to be removed to swap injectors so may have not.

 

[Flyin Ryan]

Re: Misfire at idle

I hope he put in the right plugs and at least at factory gap

 

[souljasmooth]

Re: Misfire at idle

Whatever gasket that needs to be removed when changing out injectors, is the gasket the mechanic changed. Im thinking he did NOT change out the lower intake gasket. Ill ask him about it tomorrow. What is factory gap?

 

[Tooky]

Re: Misfire at idle

Factory gap is .035. Nobody would replace lower intake gaskets when doing fuel injectors, there's absolutely no reason. Not to mention the fact you'd have the add'l hassle of pulling the distributor and re-timing the truck, when doing a lower intake.

Check for vacuum leaks in all vacuum hoses. Read my website: www.powertuneplus.com

What are your IAC counts at idle on a scan tool?

 

[souljasmooth]

Re: Misfire at idle

You guys were all right. It is the lower intake gasket that is causing the misfire. Now where can I get a set? I tried calling everyone, and nobody has any. The dealer discountinued the set years ago.

 

[Loeryder]

Re: Misfire at idle

Mike Hood at Tucker Auto Parts can hook you up.

Ive bought nearly all of my gaskets from him

 

[souljasmooth]

Re: Misfire at idle

Talked to Mike, he had exactly what I needed...thanks

 

[ZavzTy547]

Re: Misfire at idle

Talked to Mike, he had exactly what I needed...thanks

I'd check your timing first before you change the gasket.
Alot of misfires are caused by advanced or retarded timing. especially at warm up when the ecm is trying to compensate in closed loop.