Ok....just recently my 94 Formula started running rough. It's not horrible, but just a little rough...noticeably. I replaced the plugs and wires a few months ago.

I'm wondering if I have a burnt wire maybe, but I was wondering how you check the wires with them still being on the car??

Also, could it be a coil? And how do you change the coil on an LT1???

I did a search through the archives and read about some EGR or PCV-related problems, but would appreciate more detail on these. How to replace, etc. Could either of these be my problem?

Any help is really appreeciated!

Phil

 

The engine can be connected to an anylizer while it's running of course and the signals can be checked for bad condition to each plug and it can be determined if wire or plug or distributor.

The coil is on the front of the drivers cylinder head close to the opti. Check all the connections for the computer and ignition system for loose, corroded or bent condition. Take your time think about the symptom closely before you just start buying parts.

The $60.00 or so to anylize could be a wise investment if it saves you from spending $198.00 for an opti(not to mention the time to replace it) and turns out to be something much easier.

Did this occur before you changed plugs and wires or just since you changed them? What parts did you use (GM or some other brand?) Are there other parts that are in need of routine relacement like O2's? The folks on this board are pretty sharp they can help you. Remember to check the easy stuff first and check check check before you buy.

Good luck

 

By the way does it run rough at idle only or at all speeds, is it when cold or after warm up? Knowing these things means a lot.

Stupid suggestion, look under the hood at night with the light off, and see if you see arcing anywhere.

 

Alright...thanks for the advice. I changed the plugs and wires (Moroso LT1 Bluemax wires and AC Delco plugs) several months ago, and the rough running started just a couple of weeks ago.

It runs rough pretty much at any speed...at all times. I've had the car since approx. 75K miles (now it's at 102K) and I've never replaced the) 02 sensors. How do you tell if those are bad?

Thanks for the help,

Phil

 

Maybe someone has a different idea but I would have the injectors professionally cleaned through the fuel rail. Not like Jiffy lube does with stuff in the tank. That's ok for routine (every oil change) but they need a good blowin out so to speak. I got my hose & connectors to do it myself from NAPA and only use the 3M refill cans.

I would also check the throttle body for cleaning and while your there clean the IAC it never hurts. Check and clean the EGR and finally replace the O2s with OEM units. Dal can probably save you money on them call him at 877-448-5451. Got the best prices in US on most GM parts. Nice guy too.

If none of that solves the problem get it hooked up to an ignition analyzer.

Enjoy working on it don't think of it as a chore.

I hope you fix it.