dave85c4

I have an 85 that was running fine, then started to miss. Changed plugs,wires cap, and rotor. Ran good for about 3 days. Started it up and some garbage came out the exhaust and it started missing again. I have a new fuel filter to put in but what else may it be? At crusing speed without appling gas it doesn't seem as bad. When you get on it it starts to miss. The warmer it gets the worse it is.

Mace

That's a tuffy. What kind of 'garbage' came out of the exhaust? Could be injectors or ecm. I had a problem like that years ago with my first 85 and was the ecm. But my problem occured only at higher rpms.
Mace

dave85c4

a little oil smoke, but that may have been from a valve seal. It doesn't do that all the time. Coming to work this am if you hit hit at crusing speed the car shook but still took off. You can feel the miss.

95CYC4

Since you said it gets worse with heat it might be a resistance problem with something electrical. Have you checked your coil yet? Maybe you should change that and see what happens. Also pull out your plugs and check them for discoloration. At least you can see if your ignintion system is working correctly. Have you filled up with a new tank of gas lately? Maybe you can try adding something to your gas to see if you have something clogged or bad gas. Air cleaner is clean? EGR valve working correctly? These problems can come from alot of sources, just try all the easy ones first since it is most likely one of them. Good luck, and lucky you don't have an opti-sprak on your car or you would have had an easy answer from the people on the forum. :cheers:

dave85c4

I just checked the engine codes, just 12. I've tried gas treatment and filled the tank with fresh gas. tonight I will put in the new fuel filter and check the plugs again. Maybe one of the new plugs went south. I hope. Gas mileage is going to hell so maybe its only running on 7.

BobMachus

Since you have replaced most of the ignition components, you should look close at your coil, and then your coil module. Especially with the shaking at part throttle when cruising, this could be a miss that only appears under load. Look at your plugs they can tell you alot about what is wrong.

dave85c4

replaced fuel filter tonight, no different. Replced coil, Took cap off and found #1 post looked bad. Checked #1 plug and that didn't look good compared to others. Cleaned up old cap and rotor and it seemed somewhat better. Will get a replacement cap and rotor Friday and try again. If that doesn't work its time to head for the shop. :confused:

BBA

I had a similar problem on a 3.8L V6 once...I found one of the plug wire terminals inside the dist cap had arc'd through the cap and was grounding on the coil's body. A new cap and rotor fixed it good as knew.

dave85c4

Well put a chevy cap and rotor still no change. New air filter too. It's really starting to bug me. My have to put my 5.0 GT back on the road, ya right.
Checked the dip stick no coolant showing. Level is fine. What do you guys think. Injectors dirty or plugged?

LT5

kill those CATS!

importeater

could be a few things, normally a leaky injector won't do that, a bad coil would but since you replaced it. test fuel psi. make sure it's stable, if the regulator goes it would cause that condition. hmm..what else. a vac leak comming from somewhere would do it. i had a similar probelem & never did figure it out {mine was probably the coil} after i put a msd box and blaster 2 in it cured it. also had issues with the adj fuel regulators..i HATE these things on L98's i seriously have heard more bads than goods. they all seem to create sputters, leaks and issues..from now on my fuel curves are going to be tuned with prom curves and injector size

importeater

also did you know a code 12 means...diagnostic mode; no distributor signal to electronic control module; system PASS

dave85c4

Turns out I had a bad injector on number two. Leaking real bad to the point of getting in the crankcase. Have got the motor torn down waiting for new Accel injectors. Hope to have it running by the weekend. While I have the the runners off anyone have any ideas on how to clean the up. The other owner (female) took care of the mechanics but did not clean the engine.