Last night I looked at our '93 SSEi to determine why the boost wouldn't go above 0 PSI and the engine stumbled and lost power when trying to accelerate while boost was at 0 PSI. The problem began yesterday. There were no error codes or other symptoms; the engine started and ran fine except when under load.
I suspected the Boost Control Solenoid, Boost Bypass Valve, or maybe plugs or wires. Although I wasn't planning to test them, I decided to check the coil packs first, because they were quick and easy to check, and to my surprise, the problem was that the coil pack for the #1 and #4 cylinders was completely open circuit. I was surprised that the engine could start easily and run ok except under load when a coil pack was open, but that'* what happened in my case.
Maybe this info will help someone else who encounters a similar problem...

Wow, that is amazing, the coil pack delivers no spark?

May I politely ask how you went about testing the coil packs? :?

Macdrive, try Techinfo. Procedures and specs are there.

Mac, go here for the procedure

http://www.bonnevilleclub.com/forum/...e=article&k=33

Billha, that seems really strange. With an open, you wouldn't think that it would fire that pack and the engine would idle and run terribly. Is it the primary, or secondary windings that are open? The only explanation that I can come up with is that the windings were capactively coupled, which could sustain spark under light loads.

I used one of my digital multimeters, and testing only took a few minutes.
Sorry if I assumed that others knew about that kind of stuff...I'm an electronics engineer.

Whoa!
What you describe is exactly how my SSEi is behaving. It has a tough time getting over 0 boost, and when it does it stumbles, and makes a sound like it is backfiring out of a carb (which is impossible.)
Will also suggested I check the coil packs, I'm going to pick up a multi-meter tonight, follow the instructions, and let you know how it goes.

Thanks,
Adam

Good luck. Mine didn't make "backfiring" noises, but I let off the accelerator when the engine bogged down. In my case, the coil pack looked normal on the outside - there were no cracks or unusual marks, and the posts were clean and intact (not loose).

If it'* not a coil pack problem and there aren't any error codes, it could be caused by several things, but the next step may be to check the plugs and wires, and then the boost control solenoid and the boost bypass valve and the vacuum connections to those parts.

Hi everybody.
I'm happy to report it was indeed a malfunctioning coil pack.
Crazy stuff.
Thanks to Will'* link for testing the packs, I found one that had the primary resistance all over the map.
As luck would have it, I happened to have a set of packs in my basement from when I had a 2.8L Chevy Celebrity. They used the exact same packs, same part number marked on the bottoms. I checked that set, and replaced all 3 and off I went.
I took it for a test drive, hit the gas, no more hesitation, no more funky noises, gets to boost quickly, and the car takes off nice.
When I walked back into my house I looked like this:
My wife said, "I take it the car is fixed"
Yes it is, for now...

Thanks again to all. I have a few posts on the go, so I will add this note in case others are experiencing the same problem.

Cheers,
Adam