ThirdGenKen

I have a 1987 Iroc with a 383 stroker and a supercharger. Every since the last time I did a burnout, the car has been running real crappy. It idles ok and everything, but under load it feels so restricted. It's like nothing is there. When I get on it, it just doesn't go like it should.

I thought the coil pack was bad, because I saw it sparking outside the wire. I installed a new coil pack and coil wire, but it's still doing the same thing. Someone I was talking to said it could be a fuel issue. That it might be getting enough fuel under load. They said I should put a fuel pressure gauge on it.

What do you guys think??

ThirdGenKen

bump

ploegi

Is the ignition system working as it should now?

Think I would be tempted to do a compression test....

ThirdGenKen

Yea I believe so. It has an MSD ignition system. It has MSD wires. New MSD coil. New AC Delco spark plugs.

I do have a 100 psi liquid filled fuel pressure gauge in the car. It is always at 40 psi and never goes down. When I turn the key off, it slowly goes down between 20 psi and 10.

So, does that mean I have a fuel problem or is that normal?

One other thing I noticed is that the exhaust sounds different ever since it started running like this. Is it possible that something in the muffler could have broke loose?

I was thinking possible clogged fuel filter, but I would have less fuel pressure right?

ThirdGenKen

Chances of it losing compression are low. The crate motor only has about 25,000 miles on it.

Damon

Did the distributor possibly slip and retard the timing? Or, if you're running an old-school non-computer controlled distributor the centrifugal advance could have gotten hung up. Check the cap and rotor visually inside just to be sure you didn't toast some internal contact or something (burnt coils and/or coil wires are often a sign there is a high-resistance issue further down the line, although this is somewhat par for the course in a boosted application with much higher than normal cylinder pressures).

When you say it "sounds different" that usually means timing changes, unless the valves are making noise (which you didn't note, so I'm going to assume nothing bad happened to the valvetrain).

Do you run a cat? If so, it IS possible the bricks inside have come unglued from their moorings, shifted or slid back and have become a restriction, but this is pretty rare unless the cat is old. A muffler with similar "broken inside parts" would be exceedingly rare these days, and is usually accompanied by a notable rattle, usually worse when cold.

Doesn't sound quite like a fuel issue to me, either. It would be worse than just low on power. It would be stumbling, surging, popping and generally falling on its butt under boost as the RPMs climb.

If it sounds like I'm leaning more towards an electrical/timing/wiring issue than a mechanical one, you'd be right.

ThirdGenKen

I guess it is possible the distributor could have slipped. I'm pretty sure it's a computer controlled distributer, but not positive. I will pull the distributor cap and check that next. The coil is new and I tried changing the coil wire. It didn't change anything so, I put the old one back on.

The exhaust sounds different. Almost restricted I guess. The engine sounds ok.

I do have a cat, but not sure how old it is. It was all on there when I bought the car. It doesn't look new though.

The muffler looks pretty old too.

ThirdGenKen

Well, I found out why my car was losing power. When I replaced the spark plugs, I must not have pushed one of the wires on all the way. When I lifted the car up in the air, one of my plug wires had come off the spark plug. Although, I did do a full tune up.

New MSD wires
New MSD coil.
New MSD distributor cap and rotor
New spark plugs.
New fuel filter.

It's running better now, than it ever has since I bought it. This car is nasty.