I have not checked the fuel pressure or the coils.

My mechanic was equipped to check for codes and I think he's very competent.

When he scanned the original pcm it was so flaky he was sure it was bad. It was showing lots of codes that didn't make any sense, and the readout would change every time he turned the car on and off, so I do think it was bad even if it was not the cause of the problem. Before he replaced it I was unable to calibrate the compass, so that may have been another indication of a bad computer.

The plugs and wires were recently replaced, and are good.

Coolant level has been fine.

If it flakes out on my trip Sunday, I'll have him check the coils and the fuel pressure.

I think I already gave a good description of what the car was doing, but here is is again. On a trip a few weeks ago I was cruising at around 80 for 2 hours when the car began running bad; bucking and gradually losing power. I exited and tried to drive to a friends house. It died in town on the way, would not start until I let it sit for 15 minutes. It started right up and ran fine. Then next day I replaced the fuel filter. On the trip home the next day, it did the same as the day before.

New computer was put on, but the next day the car crapped out in town. It was 96 degrees that day, and I was running errands with a friend, and between short trips in town he stayed in the car, so I left it running in park 2 or three times within a 45 minute period. It crapped out after that just like the previous times. It finally died completely, but started right up and ran fine the rest of the day.

It's been running well today so far since I got the cat replaced with a straight pipe.

Your PCM has no effect on the compass whatsoever.

Go to your local parts store and BUY a fuel pressure tester. The next time the car stalls, pull over RIGHT AWAY, hook up the gauge, turn the key to on (no start) and record the fuel pressure. I suspect your pump is failing, especially after a long run (getting hot).

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Thanks WillWren and everybody. I'm taking a 100 mile trip today, and we'll see how it goes. If I flakes out I will buy a fuel pressure tester. I'll keep y'all posted! Larry

You should have it in the car before you leave. Otherwise you won't catch the problem if it's fuel pressure related.

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Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

Somebody is gonna throw a rock at me, but I still think there's a good chance it's the ICM. It can take out your coils too, at least on the Magnavox of mine it did. Mine never threw a single code. - BC

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Big difference. Delco ICM's typically won't even let the car start when they fail.

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The car ran perfect today under pretty much the same conditions under which it's been flaking out in the last month. Willwren-- I know you're right, but I just can't afford to buy many tools or gages right now, so I thought today's drive would confirm whether or not it was the converter. So far that seems to be the case, but I've got a 450 mile trip tomorrow, and am hoping it runs well on that trip also.

Larry

If you went 100 miles today and the outside temps were at least 80°F, your catalytic converter is not your problem.

As far as a fuel pressure gauge goes, Autozone will loan one to you for a deposit only. It's also an invaluable tool that will work on nearly any modern vehicle, and they don't cost much. I suggest the Actron at Autozone. While I usually try to steer people away from teh zone, Actron is a recognized name brand with quality. It will be less than $50, and will last you a lifetime.

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Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

I already had the cat replaced 3 days ago, so since it ran good today I'm thinking that was probably it. The temp was about 90 today.

I just re-read your post above. That straight pipe is costing you fuel economy and performance. It's also illegal as hell, and may get you fined.

When it was cut out, did someone CHECK it for you? I would hope so, because that would have answered your question. Did you keep it? I hope so. It's worth $50 or more in scrap value.

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Comprehensive guide to troubleshooting, rebuilding, and modifying Eaton Superchargers

If your convinced with a couple more runs that the problem was indeed the cat, buy a magnaflow replacement cat and have the place that cut it out put it in.

Look for something like this.

http://cgi.ebay.com/ebaymotors/Magnaflo ... ccessories

The car ran like a charm-- 7 hours at 70-85 and no problems, plus my mileage was 29 which is a big improvement.

Thanks for the cat link, I'll order one soon and have them put it on.

Thanks again for all the help, everybody.

The drama continues. I started off on a trip this morning and the car suddenly completely died. No missing, stuttering or bucking like previously. Fortunately I was only 2 blocks from my mechanic. There is no spark, so now we're thinking crank sensor. I'll keep y'all posted on what we find out...

Sounds like a completely different problem has sprung up.

yeah, I agree. The old ECM was definitely bad, and replacing the cat did fix the latest problem, but this does seem like a new issue.

OK, back from the shop. The crank sensor tested bad, and got replaced. Car running fine, so far.... Hopefully we can close this thread, I hope to make no more reports!