93 Gran Prix intermittent problem

'93 Gran Prix, 3.1, 120K miles, mom's car. Engine will run perfectly for a time and then suddenly lose power, idle very rough, and then after a short time it will come out of it
"instantaneously" --which suggests to me it's something electrical rather than fuel related. She says she smells fuel when it's doing this. Took it to a dealership, described the symptoms, and they couldn't get it to act up on them (of course), but they changed plugs, wires, & fuel filter, just because it had never been done in 120K miles. The car's not had anything but a battery and tires replaced since she bought it at 59K, so I'm quite sure nothing's been done to the car other than what we've done. I knew that making the above mentioned repairs wouldn't address the way the car had been acting, and it didn't. I'm wondering if it's not a coil pack going bad, since it had original plugs and the coils have probably been working WAY overtime trying to fire those worn out plugs which probably had huge gaps by now. That's kind of how it runs when it's acting up--like one of the coil packs suddenly delivers weak spark, then snaps out of it. BTW when it first happened, it had just gone on a long drive on interstate, 3 hours at 70 mph, stopped to eat, came out and it would barely run. Then it just snapped out of it and ran fine all the way home until sometimes when I'd stop at stop sign, it would run very rough and then I could give it gas and after a short time it'd instantly snap out of it and have full power. Is that typical behaviour of a bad coil pack, ign module, something else..?
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James Goforth wrote:

EGR is probably all gunked up.
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Check engine light on? Sounds like its more of an electrical problem to me. Ignition modules that go bad, act this way sometimes. Nothing like having a F'IN dealership throw parts at it! Worse than lawyers!!!
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No check engine light. I went ant talked to the tech today, seemed competent, ben there for 11 years. I went there to describe how it acted since it didn't act up for him and he's getting his info from a 79 year old lady. But he had just driven it and it finally did do it and he thought it acted like maybe a bad coil pack. So anyways...she comes home with it this afternoon and they installed 3 new injectors..said they were "weak." And maybe they were, but--say it with me-- it still acted up on the way home. In all fairness to the dealership, though, I thought it was a bad coil pack and so did he, and he ruled out those for a reason. Another poster said the egr could be gummed up, now I think that might be possible, although I'd think there'd be a MIL for that. I found the one on my '89 2.8 multiport to be stuck solid, although it ran fine, put another one on and it wouldn't run right until I plugged off the vacuum to it (what's up with that)?
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If the mechanic also suspected the coil pack why were only the injectors changed and not the coil pack. The ignition module is integrated in the coil pack. If they are going to start throwing parts at it, tell them to start there. Jim
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No it's not.
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Timing signals below 400 RPM come from where Big Steve. Atta Boy./.. Knew u could figure it out! Change the coil pack or ECM to fix prob. Jim
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I got you a present for Christmas, a free subscription to my killfile.
Merry Christmas.
Your Pal,
Steve
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Problem was a bad ignition module. I guess it logically follows that you'd get no MIL for this.
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Was the coil pack replaced to repair the prob?
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They found tracking on one coil pack and replaced it, but the problem persisted. Replaced ign module itself and so far so good.. They haven't presented us with a bill as they want her to drive it around a little while and make sure that was the problem. I gave him a little bit of crap about messing with the injectors when the problem wasn't anything that replacing injectors could possibly address.
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Now I'm thinking it's just the cmputer itself, putting the timing way out of whack or something, no MIL due to this..? That happened to my '89 2.8 mpi once. Will post findings.
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