Annoying elusive misfire

[Gasser64]

What are the most common misfire causes on the 302 cars? I have a 94 GT and its got a bit of a stumble at idle. I talked to my long time mechanic friend, and he said that 99% of the time, its the same problems coming in on the same cars. He said they'll get some odd stuff in every once in awhile, but once you've fixed a few, you begin to notice a pattern. He said nowadays, he can pretty much go right to the problem a given vehicle is having, just because he's fixed that same problem on so many others already. And that this is a recurring theme with most vehicles.

Given his response, I wanted to ask this question. So what is the common misfire that most of these 94-95 5.0's get? My other one also had it. My buddies cars have had it, before they sold them. I'd be willing to bet its something that most, if not all of them suffer from until its corrected. Anyone have any idea?

I've given it a full tune up, dizzy cap, rotor, plugs, wires, O2 sensors, air filter, fuel filter. It has maybe 5k miles on that tuneup. So what else? What are some areas I could check? I dare say that I do have a few automotive repair skills, but apparently, finding misfires isn't one of them. Cause this one is eluding me. Might have to send a PM to Whiteboy if he doesn't post in this thread.

[BMCSean]

An sn95, interesting. They are notorious for computer issues. What mods are done to it?

[black90notch]

I had an issue with the reluctor wheel in the dizzy hitting the pickup for it and causing a miss.

[Gasser64]

An sn95, interesting. They are notorious for computer issues. What mods are done to it?

Little. Sve lowering springs, Bilstien shocks, K&N, 3:55 gears. Might be a couple more, I'll mention later if they come to mind. The standard laundry list of repairs.

I had an issue with the reluctor wheel in the dizzy hitting the pickup for it and causing a miss.

Somehow that sounds like the type of crap that would happen to me. lol

How the hell did you find that. Hours and hours of troubleshooting?

[shumpertdavid]

How the hell did you find that. Hours and hours of troubleshooting?

You take the cap off, grab the rotor and see if the distributor shaft has excessive side to side play.

[Gasser64]

Now that I've done before, at the time of the tune up. Didn't have any play at the time but its been about 5k miles. When I get time I'll give it another try since its so easy to get the cap off.

The intake gasket has already been replaced, so I'm fairly certain its not that. When I got the car it had a BAD misfire due to the plenum gasket being bad, so that was replaced immediately.

[A+]

Does anyone have a moded 94-95 that works well?

[Gasser64]

Does anyone have a moded 94-95 that works well?

hey bruh, you got a problem with sn95's?

[Gasser64]

I'm aware that the 94-95 cars are known to develop distributor issues. And I think rebuilding the dizzy would be fairly cheap. Minus the cap and rotor, which are fairly new. Anyone still got that diagram of the dizzy guts? I know I've seen it on this site somewhere. Shoulda saved it

So maybe if I replace the pickup coil, the PIP (which is known for causing phantom misfires) and the coil, I can eradicate this annoying miss that is driving me crazy.

I found this, anyone here recommend it?

http://www.americanmuscle.com/accel-tficoil-849550.html

[AnthonyS]

I'd pull the codes. Just because you have no CEL doesn't mean you aren't throwing codes. If you have a spare TFI module swap it out too.

[Denny]

Ya, TFI was my first thought after you mentioned the recent tune up.

[lilvega]

I chased issues with my 94 until I narrowed it down to the computer. O2 sensor had shorted somehow and lunched the computer. I put a new one in and it was instantly better. Then I purchased a Moates j port chip and tuned it. Ran much much better.

[snacksnack]

If your interested I have a reman dist from either oreillys or autozone ( cant remember which one) with maybe 50 miles on it I would let go for 50 bucks. Seems like I paid around 100 for it when it was all said and done.

[Gasser64]

Think I'm just gonna rebuild mine, but thanks anyways. Thanks for the help everyone.


Gonna have the TFS tested... somewhere. Maybe vatozone


EDIT

Isn't there a way to test your coil with just a voltmeter? Cant remember

[Gasser64]

Found this:

"To test the coil;

get an Ohm meter and

check primary resistance between Pos and Neg terminals on the coil
resistance should be 0.3 - 1.0 ohms

check secondary resistance between Pos term and coil wire terminal
resistance should be 8000 - 11500 ohms

repeat secondary resistance test between Neg terminal and coil wire terminal
resistance should be 8000 - 11500 ohms

check resistance to each terminal and gound(coil case)
resistance should be infinite."

Hmm... Everything is in spec according to what I posted in bold, on the older coil I had laying around. But on the coil that came off the car, it says infinite resistance between both the terminals and the coil wire terminal. So to clarify when I check each terminal against the coil wire terminal, the resistance is infinite. But between both smaller terminals themselves, the resistance is in spec. So now of course I have to ask how the car could even run with infinite resistance between the terminals, and the coil wire terminal. Seems like it shouldn't. And I'll go ahead and replace the coil with the older one I had on the shelf.