Intermittant miss

[scott209]

I am new to Reattas. I have a 1990 convertible. I have noticed on occasion that I get an intermittant miss when going up 2-3% grades at freeway speeds at 2000 rpms. I've seen similar posts and answers most notably from Padgett. His comments concerned the ICM. I've taken mine out and had it tested. It was okay.

Is this an ignition problem or is it a transmission problem because this is the speed when the transmission is deciding whether to be in 3rd or overdrive?

Scott

[Guest F14CRAZY]

It's very possible for an ICM to test as "good" and be bad, at least with Magnavox 3800 coils. I would suggest going ahead and getting a newer style Delco coils, you won't have to worry about it.

If the miss shows up in overdrive but seems to go away in 3rd gear (highway cruising) I'd say with pretty good certainty it's your ICM. If you haven't replaced your plugs and wires in a while I'd suggest that too for good measure

[padgett]

Actually that miss is usually one of the coils in the triple pack going bad (ICM may be good). I recommend going to the Delco unit because the coils are individually replaceable if one goes bad and the spark is stronger.

[Guest F14CRAZY]

My bad Padgett, I forgot that the "ICM" is just the base, not the black towers

[matthewlawe]

Keeping this thread going as I have just experienced something very similar.

Shifting into overdrive, speed around 45mph, the engine would “shudder”.

My first reaction amazingly was to shift manually (old habit) into a lower gear

but I haven’t driven a manual since I bought the Reatta. I did shift to D2, it

helped, but when the RPM’s decreased as I slowed down, more shuddering.

Would you please take a shot at a diagnosis? I had also just had the water

pump replaced. Thank you.

Regards,

matthewlawe

1989 White/Blue

[Lucky91]

Sounds like a lock-up problem. How many miles on this car. When was the last time the tranny was serviced? Could be as easy as having the tranny seviced with a fluid changed. Then again it could be more. You might want to have it checked out. Good Luck..

[Ronnie]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 91Polo</div><div class="ubbcode-body">Sounds like a lock-up problem. How many miles on this car. When was the last time the tranny was serviced? Could be as easy as having the tranny seviced with a fluid changed. Then again it could be more. You might want to have it checked out. Good Luck.. </div></div>

To confirm the lock-up problem, go into diagnostics mode on the CRT and see if the shudder occurs when the TCC light comes on.

[Vincent Vega]

More than likely it is plug wires. Very common symptom.

[matthewlawe]

Thank you very much, fellows. This will get me started.

I'm currently in the middle of recarpeting the interior

and when I finish up, I'll look into this - diagnostics

and all. Two to three years for both plugs and transmission.

Regards,

1989 White/Blue

128,000 miles

[scott209]

I just finished "The Padgett Upgrade." I found a Delco mounting plate, ICM and coil packs on a 1995 Buick Park Ave. I installed the Delco unit but it didn't fix the problem of an intermittant miss at 2000rpms.

The next step seems to be to replace the plugs and wires. The plugs and wires were replaced 4 years and 3000 miles ago. Should I replace them anyway and with what?

[padgett]

I like AC Rapidfire #14s gapped to about .055" (real tight .060) with the Delco ignition. YMMV

[scott209]

Update.

I ended replacing the wires and plugs but the problem still happened occassionally at 2000 rpm, slight incline when the car shifted between 3rd and overdrive. I checked the transmission fluid again(I previously had a transmission seal leak) using the precise directions in the owner's manual. It turns out I was about 3\4 pint low and this seems to have corrected the problem.

It's probably my imagination but the Padgett upgrade seems to have added a little pep.

Scott

[BillN]

I had the same problem and it turned out to be the ECM(Engine Contol Module) that wasn't firing one of th einjectors. Easy to diagnose. Mine would come and go at idle also, so when it was acting up, I pulled the injector connectors off and looked for a drop in RPM, when I didn't get one, I knew something was up with that injector. I then plugged a test light into the injector connector, and it didn't illuminate, so I checked the continuity of the wire and it was fine, leading me to suspect and change the ECM. Replacment at the auto parts store was $95.

[Guest tomt]

I don't see it mentioned in the thread, and I had the same problem. I replaced the wires and the fuel filter. The problem is gone, but I don't know which fixed it. The wires tested marginal, so I think the filter may have also been a culprit. It's simple and cheap, so if you haven't you should.

[Guest MauiWowee]

The 3.8 must be sensitive to their plug wires. I had a miss that was only fixed by the second set of new wires.