96 Buick Regal misfire, #4 cylinder

Just found this problem, engine light on showed a misfire. Had shop double check all of the injectors and fuel pressure, all good. Install a new fuel filter. Then did a new plugs. Thought it might be a spark plug wire, installed a know good one, no fix. Then swapped with the one next to it, still no fix. Replace coil, no fix. Now trying to decide what is next. Have you heard of a problem with plate the coils set on? I believe it called a solenoid assembly? Not sure though. Thanks, Tom

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tpetaja
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Reply to
Shep

At idle you can notice the miss and also get codes. At higher speeds, you don't really notice. i have not tried resetting the code at higher speeds to see if they stay clear. The car seems to run great, just the low RPM misfire. Tom

Reply to
tpetaja

Vacuum leak Don

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Reply to
Don

AFAIK, there are two engines available in that model. Do you perchance have one of them??

The 3.1 should have the DIS ignition system. One bad wire will cause two cylinders to miss.

That engine has some potential for problems from leaking intake manifold gaskets.

The 3800, which is the other, is susceptible to the dreaded plastic plenum problem. When this happens, coolant can leak into one or more of the cylinders. Often the failure happens rapidly, but in the outset, it can act like a miss, and a scan may well show misfire or multiple misfire.

There are other possibilities as well.

Reply to
<HLS

The engine is a 3800. I did replace the ICM tonight and saw the same issue with #4 cylinder. Only new item I did, was warm the car up and then took it for a ride. I shut it down and cleared the codes. Then I drove around at the higher RPM. I notice that the misfire did not trip. It DID trip, once I got to the house and sat in the drive in gear, lugging the engine. Tell me more about the plastic plenum issue. Some notes: I got the plugs replaced, but did not notice any fouled plugs. Anti freeze seems normal. Thanks, Tom

Reply to
tpetaja

The pitiful plastic plenum pendejada came to birth in 3800 series II engines, made after about 1995.

This fuel injection plenum was made from plastic, which tended to deteriorate and fail, with time... Some failed early, some later.

(Ours failed at 76,000 miles, approximately).

When they fail, coolant can enter one or more cylinders. The car can run rough at first, and later can become impossible to crank over because of hydrostatic lock.

If it is out of warranty, GM just flips you off.

A new and improved plastic plenum is available from NAPA and others for roughly $150. A local independent mechanic quoted me $100 to change it out.

I had the local Buick dealership do ours, and they gave us a decent price... maybe someday GM will face up to it crappy engineering and parts and make it good. (Most likely, they won't)

If you stroll into a Buick shop and try to get this replaced, they often quote $700-$800 US dollars.

Do they all fail? I don't know. Many do, and with time you would expect a lot do. If you are caught on the road, having to stay in a hotel, and at the mercy of whatever garage you may encounter, it can be an expensive vacation

Reply to
<HLS

I will check for this. I did do a search on this one and saw several hits for this problem. To date, we are not drawing much water if this is truely the problem. I guess I can't complain too much, we have

160,000 miles on this car now. Again, I will do some checking on this one and I may just bite the bullet and get this replaced. The engine and car are in good shape and I would rather do that then replace it. Thanks for you help. Tom
Reply to
tpetaja

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