Car doesn't seem to be running "right"

[Chris07GT]

Car doesn't seem to be running "right" - FIXED!

My car doesn't seem to be running really strong lately. It kind of started around the time that I had my headers installed, but I don't think it's related to that. It kind of seems like it has a little bit of a misfire or something. I can notice it mostly at lower speeds, like just off idle. I also got a misfire CEL the other day. I dont think it's tune related, because I switched from my dyno tune to a brenspeed tune and it's still there. I noticed it a lot on Sunday during my car clubs cruise, at high speeds it felt pretty good, but from a stand still it seems to have a hesitation.

I'm not really sure where to start. One thing I did is bought a used set of factory COP's to see if it's related to that. I have the MSD ones and I know a lot of people have had problems with them. I recently changed my fuel filter and my spark plugs and also cleaned out the MAF and the air filter. Any other thoughts on what it could be?

 

[Cali HP Addict]

My missfire and progressively poorer running turned out to be clogged cats. They visually look perfect, it took a special pressure gauge in the o2 sensor bung at Ford to finally diagnose. I did have some initial tune overfueling problems which probably aided in their deterioration.

 

[Chris07GT]

My missfire and progressively poorer running turned out to be clogged cats. They visually look perfect, it took a special pressure gauge in the o2 sensor bung at Ford to finally diagnose. I did have some initial tune overfueling problems which probably aided in their deterioration.

I'm running an off-road H, so no cats to get clogged up

 

[Jeffs FRC]

Did you install the factory COP's yet?

 

[Chris07GT]

Did you install the factory COP's yet?

Not yet, I just bought them last night, so they aren't here yet

 

[Jeffs FRC]

Not yet, I just bought them last night, so they aren't here yet

Well, since your getting that misfire cel I would bet on the COP's. It does seem like many have problems with those msd's... If the COP's don't fix it I would have your tuner take a look.

 

[07 Boss]

I had a broken insulator on the tip of one of my plugs once that gave me the misfire CEL and it was a bitch to track it down. One reason why it was tough was if you held the plug tip up, you couldn't see anything wrong. When you held it tip down, the ceramic insulator would slide down shrouding the electrode. Took me two times pulling the plugs before I spotted it. Only reason why I mentiond this was because you just changed yours out and I had just changed mine out when I had the issue.

 

[TonyN]

I have a feeling you are on the right track with the coils. OEM ftw!

Also, when you install the coils blow out the spark plug wells to ensure there is no moisture in there from possibly spraying down the engine or something. Make sure your TB is squeaky clean. Even though that typically won't cause a miss, they can give you some idle issues when gunked up.

What chemical did you use to clean the MAF? No noticeable exhaust leaks?

 

[Chris07GT]

I used MAF cleaner to clean the MAF. I've never touched the TB, should that be cleaned. I'm at 30k.

Would an exhaust leak really cause a misfire/hesitation?

 

[navbtcret]

Did you reoil your air cleaner? If so you may over oiled it and have oil on your MAF causing this.

 

[J2L06GT]

I had a broken insulator on the tip of one of my plugs once that gave me the misfire CEL and it was a bitch to track it down. One reason why it was tough was if you held the plug tip up, you couldn't see anything wrong. When you held it tip down, the ceramic insulator would slide down shrouding the electrode. Took me two times pulling the plugs before I spotted it. Only reason why I mentiond this was because you just changed yours out and I had just changed mine out when I had the issue.

+1 on this, had the same problem when first installed Champions,
started out as slight miss at idle then got worse, after new plug
been running good for 2 years.

 

[Chris07GT]

I'm going to start out changing the cops and see if that fixes it. If not, I'll check the plugs. I just installed the champions gapped at .035, so maybe the plugs are causing it.

Is there any way to tell which cylinder is misfiring?

 

[J2L06GT]

Only if keeps missing all the time, then unplug COPs
one at a time to find.

 

[jroc07gt]

That's a small gap for just bolt ons and could give you a rough idle and hesitation at part throttle if not tuned for it

 

[one eyed willy]

I'm going to start out changing the cops and see if that fixes it. If not, I'll check the plugs. I just installed the champions gapped at .035, so maybe the plugs are causing it.

Is there any way to tell which cylinder is misfiring?

you sure we gapped them that close? i was thinking .045?

 

[Chris07GT]

you sure we gapped them that close? i was thinking .045?

Yeah, I made a typo, it was .045

 

[MikeVistaBlue06]

Have you used any octane booster? If so, search on the term MMT and you'll find your answers.

HTH

Mike

 

[FORDIFIED3V281]

I was having this problem and just changed my msd's yesterday. I had another set you could have got from me for free to see if that was the problem or not. If thats not it there is a local guy to us that can look at your tune, he fixed my miss that i had under a slow accel.And now i had a miss fire on start up, so thats why i changed the msd's. So far so good.

 

[Chris07GT]

Have you used any octane booster? If so, search on the term MMT and you'll find your answers.

HTH

Mike

Nope, never used any fuel additives. Just straight 93 octane

 

[Chris07GT]

Replaced my MSD COP's last night with a set of factory ones and the problem is still there. So it's good that I know that my COP's aren't bad, but that leaves me wondering what the problem could be. I guess the next thing would be to check the spark plugs? I just changed the factory plugs over to the champions plugs. What would I look for that would tell me if a plug was bad?

The only other "issue" that I know the car has is a slight leak at one of the valve cover gaskets. Could this have anything to do with it? What about an exhaust leak? Would that cause lost performance?