88irocz28

My 1994 Trans Am has had this high load miss ever since I bought it. I never noticed the problem until I paid for it and got out on the highway. It will basically sputter and jerk around like crazy if the motor is at low revs (< 2000 rpm) and engine load is high, i.e. throttle open a fair amount. It rarely happens when the air is cold but now with ambient temperatures in the 70s and 80s, it is becoming more and more apparent, especially if I have been driving in the city. I have a 160* thermostat and manual fan override but even then the heatsoak in slow city traffic tends to make this very obvious. It has done this even in 1st gear several times when taking off on inclines. I nearly got t-boned yesterday when the car did this again and nearly died on me. Otherwise the problem usually confines itself to highways speeds where I'm trying to accelerate moderately in 5th or 6th gear.

I am pretty sure it's an ignition problem. The car's got 114k miles on it. Plugs and wires look good to me but I have doubts about the coil. The wire going from the coil to the opti tends to crud up over time and cleaning it up somewhat bandaids the problem for a little while until the car gets decently hot again.

I've been told it could be the optispark, but those things usually go out well before 100k miles so I doubt I'm still running the factory unit. The people I bought this car from were pretty ignorant and no idea what i was talking about when I asked if the opti had ever been replaced .

Short of throwing an aftermarket coil and Accel ignition box on there that I can't afford right now, I don't know what to do. Any ideas on what might be causing this miss? Any suggestions would be greatly appreciated .

88irocz28

nine views and no replies ?? Come on guys, throw me a bone here. I know somebody's had this problem before

LT1derful

From what I've heard, Optis tend to go with little-to-no warning. You say you've checked plug/wires...have you literally pulled them all and looked? Aside from that bro, I'm no electrical trouble-shootin' pro, but I might be leaning toward the coil, like you said. Spend a little time and try to save a little money by checking everything out VERY thoroughly...if you haven't already.

BTW--I had a split plug wire that had me thinking my whole motor was ready to fall out of the car...so, don't worry too hard, might be something small and simple.

Umbrae

Things to check for:

sparkplugs, wires (may be bad and not know it, change them), coil, coil wire, try your fuel filter too. Try the cheapest stuff and then work your way up. A fuel filter is something that is often overlooked and it made a big difference on my car when it was swapped out.

-Cam

LT1derful

Very good point about fuel filter. I take for granted that not everyone is like me. I'll often replace stuff like that on the fly, just to have a fresh one. I've always liked having fresh stuff in the car.

Rodrigues

You said your problem seems to increase with heats... The main thing that makes sense to me is your ignition control module. Sometimes these can get pretty flaky because they are pretty much directly connected to the head by metal... Also another common fix is the coiil wire being corroded.

turbo_Z

sounds exactly like an arching wire or busted plug. change those and i bet your problem goes away. you are saying the car shakes real bad until you get over 2500 or so where it clear up? that would be plugs and wires.

FireAm94

Make sure your intake elbow isn't torn where to bottom connects to the throttle body.

88irocz28

Hey thanks for the replies everyone .

FireAm94, my intake elbow is a little busted up where it meets the TB but I made sure I put it on so that it seals properly.

Rodrigues, where is the ignition control module located? I definitely gotta check that out.

I will change the fuel filter and plug wires soon. Whats a good brand of plug wires to get? I have Taylor Spiro Pros on my Camaro. They've held up ok except for the coil-cap wire. It fried itself in about a year. I want something that'll take the heat this thing dishes out. All my underhood wiring looms are like glass. I touch them and they go crunch. Ironically, the Camaro, being 6 years older, has perfectly OK underhood wiring .

Fatdog

I would replace the coil wire first.See if that helps.They are good for 6 months at most here.My02

Rodrigues

The ICM is located perpendicular to the coil on the front of your drivers side head. They are both located on the same mounting bracket, I recommend spacing the ICM to reduce temps...

GeneCamaro

Sounds like your opti might be on it's way. I just had the same problem. My car got worse and worse. First it missed under high loads at around 2000RPM and then it started missing at high RPMs under WOT. Then it started stalling on me and the revs would jump. All this happened it would heat up.

Hope it's not your opti and something else mentioned over here. Good luck.

88irocz28

Wow !! thanks guys Muchos gracias for all the help. This place rocks

turbo_Z

just change the things that are cheap first. i am pretty sure a basic tune up will take care of your problem so plugs and wires man.. plugs and wires. i guarantee this will fix your problem. anyone out there whos ever burnt a plug wire in a 6 spd car should know exactly what im talking about. so dont worry b/c its not your opti.

LT1derful

I certainly do!!