90 Sunbird Suddenly Running Rough

[KrazyLoCo]

Hi All,

I have a 1990 Pontiac Sunbird SE. 2.0L non-turbo.

Last night, I was driving back from my girlfriend's on the highway and everything was fine. I came to the first stop sign, still everything was fine... then I came to the stop lights at the end of the road (about 300 feet from the stop sign) and when I stopped, the car started shaking violently and the revs went under 600 and it was trying to hang on for dear life. When I took off it sputtered badly and wasn't moving very fast. So I drove it home and parked it.

This morning, I went out to investigate. I started it up to see if anything had changed, but it was still shaking and sputtering. There was also a high amount of black smoke coming out of the muffler.

I checked the spark plugs and the gaps were fine. However, the ends were pitch black (I am guessing the same reason why black smoke is coming out of the muffler). My mechanic pulled out the spark plug wires from the distributor cap one at a time. Three of them made a little difference when taken out, and the last one we tested almost made the car stall altogether.

The distributor cap and spark plug wires are brand new. The spark plugs are about 8 months old. The fuel and air filters are new. The thing that baffles me is that at the first stop sign it was running like a champ, and when I came to the next stop a few hundred feet away, it was rattling like crazy and barely staying alive!!!

It really seems like it's getting too much gas, and that's why it's sputtering and that may explain the black smoke. The condition it's in now, I can do 0-60 in about 5 minutes. Heh... (Sarcasm... I hope)

I am so stumped and depressed. If anyone could throw some ideas at me, I'd be very grateful.

Thank you.

[abaird]

did you replace the distributor rotor when you changed caps? If the cap needed replacing than the rotor probably did too. Autozone will pull codes for free. I have used them on my truck, its cheaper(free) than having a mechanic hook it to his diagnostics machine and it might tell you something.

[abaird]

Sorry, forgot to mention a few things. I have seen plug wire sets that are shit as well as cheap spark plugs failing. If the ends are pitch black it might not be a bad idea to try a new set of plugs anyway. Or clean the carbon off the ones you have but since you only need 4 anyway I would try just replacing the plugs and rotor.

[KrazyLoCo]

Hi,

Thanks for the replies. I changed the distributor cap and rotor along with the plugs.

And today I bought 4 new spark plugs. There wasn't barely any black smoke coming out of the exhaust, but it was still chugging like before.

Also, I hooked up a code reader that my mechanic friend lent me, and it didn't see any codes.

Any other advice? I have read somewhere that I should check/change the fuel pressure regulator... does this seem accurate?

[KrazyLoCo]

Alrighty, my mechanic friend came and checked it out.

Turns out all of the chambers are getting a spark, but the number 1 piston isn't working.

My engine also makes a loud ticking noise when it's running. But it has did this since I got it 8 months ago. Is this the valves?

[KrazyLoCo]

Ok, turns out piston # 1 is burnt out.