RE><E28> Hard starting when warm?

["Chao, Harvey" <harvey.chao@xxxxxxxx>]

Chris wrote:

>>Here are the symptomes:
- - -Car starts fine when cold or after sitting for a period of time
- - -When restarting the car 15 minutes to a few hours after shut-off it
starts, but it doesn't rev up to around the normal 1500 rpm and then
drop to idle; it starts and goes to 200 rpm then revs up by itself to
idle speed. It doesn't stall. I can quickly press the accelerator and it
responds and then settles into its idle if I rev it when it starts.>>

Depending upon driving habits and pattern, this could be carbon deposits on
the back of intake valves.  I am told that if present, these deposits absorb
fuel.  So the hypothesis is that when cold, the cold start injector provides
a rich enough mixture that this absorption is overcome until the deposits
are saturated.  When warm, the absorbed fuel has evaporated, and the
Motronic is not calling for a rich mixture, so the deposits initially absorb
some of the fuel and the engine runs lean at first until the deposits
saturate again.

Try a can of BK-44 and see if that has any effect or perhaps a more
aggressive approach - there are machines at shops that temporarily hook up
to run the engine on concentrated cleaners for 15 or 20 minutes and this is
supposed to clean out deposits.

If the above works, you might consider running Redline SI-1 cleaner at one
oz./10 gal in your fuel to try and keep deposits from re-occurring.

Harvey

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