<E28 M5> low rpm shudder - due to steam clean?

[<rkoo@xxxxxxxx>]

Hi All-

Another problem has cropped up on my recently acquired '88 M5. I had the
engine steam cleaned yesterday (need to find oil leaks), in anticipation
of the Major II service I'm having done today (it's sitting at Dinan as I
write this).

Immediately after the steam cleaning, I began to notice an intermittent,
pronounced shudder/rough running, only around 1500-2500 rpm. I figured
something that preferred to be dry, had gotten wet (or knocked loose). It
was intermittent and quite varied in severity, from something feeling like
minor driveline  shudder, to a really bogged down,
holy-crap-what's-going-on magnitude. No stalling out, no problems at idle,
though. It didn't creep up again this morning until I got within a mile of
Dinan (engine was warm - 25 mi drive = 1.25hrs, go figure).

Like I said, I suspect the steam cleaning caused this only because I
hadn't experienced it before - I know correlation doesn't always imply
causation, but I'm mighty suspicious in this case. Somebody, anybody,
please venture some guesses as to what's going on, before Dinan empties my
wallet troubleshooting!

Rick
'88 M5 (kind of a dog, but a fun daily driver nonetheless)

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