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

Can you feel a miss or just getting the code?
> wrote in message
oups.com...
> 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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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

On 16 Apr 2006 14:32:12 -0700, wrote:

>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

Vacuum leak
Don
www.donsautomotive.com

> wrote in message
oups.com...
> Just found this problem, engine light on showed a misfire.

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.

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

> wrote in message
oups.com...

> 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

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

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