Intermittent Misfire/Stutter/Shudder

[Danderson]

We’ve been having a problem that seems to be an intermittent misfire. The car is a 1st gen 92 Laser RS Turbo. The problem is the most obvious at low rpm and idle, such as when starting the car, stopped at a light, moving slowly, etc. In these instances, there is a very pronounced stutter/shudder and the check engine light usually comes on. Pressing the gas will usually stop the shudder and clear the light, but if you don’t gas it, it will often stall. It’s only a significant problem when stopped on an uphill grade and it takes a while for the rpm to “catch” and increase enough to allow forward movement. Sometimes the stutter happens while driving at full speed. At these times, the CEL may or may not come on, but the stutter can be felt for several seconds, and then either stops on its own or gassing will stop it.

Here’s where we are so far… We upgraded to Buschur’s 10-mm plug wires about a year or so ago when we switched to Bosch Platinum+4 plugs. We just took it to a garage, and of course it didn’t happen for them. One plug looked darker than the rest and they changed it, along with all of the belts and the fuel filter, but we’re still having the problem. The mechanic mentioned the possibility of a coil pack, and I just read some things today that talked about the ECU.

Any ideas? We’d love to have some good advice before spending a couple of hundred dollars for the wrong part. Thanks!

 

[ddavisaf]

You're running Platinum plugs? That would be your problem. DSM's don't like platinum plugs. Switch to NGK 7's and you'll notice a world of difference.

If it were your coilpack you'd have more trouble than you're having.