[V8] Who Works on ECUs?

Buchholz, Steven Steven.Buchholz at kla-tencor.com
Wed Jan 18 13:58:12 EST 2006

... the fact remains that the behavior changes simply with the ECU swap.  Perhaps a case can be made for a temp related idle difference, but it is still true that each ECU is seeing the same temp sender.  Personally, I can't see a connection between an OXS and idle speed.  

Steve B
San José, CA (USA)
> My thought as well - the ECU would not idle this high unless maybe it thought
> the engine temp was below zero F?? even then I doubt it, and you would also
> have a very rich mixture.
> Most likely you have a major air leak or the throttle linkage is binding.
> There are a few known trouble spots. I would pull the throttle body off (not
> hard to do, but there are some rubber gaskets that could break) and inspect
> thoroughly. There are lots of bearings and bushings to get sticky.
> Dave
> Quoting Ingo Rautenberg <i.rautenberg at waratap.com>:
> > See, I still see a problem.  You shouldn't have a steady idle of 1100 to
> 1200
> > rpm (even with the auto ECU).  That is too high. Have you checked the O2
> > sensor by unplugging it?  I've had sheared O2 wires that threw the O2 values
> > way out of wack trying to  get the engine to compensate.  Bad info in  --
> bad
> > info out or something like that.  Last thing would be to check for jammed
> > cruise control rod, with the bushing at the edge of failure.
> >
> > Best of luck.
> >
> > Ingo
> >   ----- Original Message -----
> >
> >   We (yes, I sought professional help) have looked for and not found a
> vacuum
> > leak.  I think in this case the problem really is the computer, because on
> > swapping in a computer from an automatic, the idle was consistently around
> > 1100-1200 rpm with no trouble codes.  With my computer, it is down around
> > 800-900 until it decides to be in the 2000-3000+ range--this typically
> occurs
> > when pulling up to a stop sign.  If it were a vacuum leak, I'd expect code
> > 2231 saying that the output to the ISV is out of range.  The code we're
> > seeing is 2111, and the manual mentions the possibility that the Motronic
> > itself has a problem.

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