[V8] Idle Problem Returns to The Twilight Zone

[Greg Furstenwerth]

Sounds like you need a young priest and a old priest, the power of 
Christ compels you....

In all seriousness that is very odd... I haven't ever heard of anything 
like that before.



Carol, Dave, and Zach Weiss wrote:
> I owe you folks (especially Steve B and Alex at IA) the bizarre conclusion
> to the idle/ECU problem.
>
>  
>
> A couple months ago I posted about an intermittent high idle, where the idle
> would hang at some random value between ~2k and >3k after driving a while.
> It would manifest itself when coming up to a stop sign (a thoroughbred
> demanding its head, perhaps?).  Turning the car off and back on always
> brought the idle back to where it should be.  Codes were idle stabilizer
> short and engine speed sensor.  Shop replaced both and cleared codes, but
> the speed sensor code kept coming back, and the intermittent high idle was
> now occurring after only a few minutes driving.  They also rung out all the
> wires from the ECU to the sensors, and cleaned connectors in the engine
> compartment.  They did check the throttle for sticking, including the cruise
> control bushing, but cycling the power contraindicated a mechanical problem,
> anyway.  I have the IA chip, but that does not seem to be relevant.  The car
> does also have intermittent instrument cluster issues (water temp and fuel
> gauges don't read) but they didn't correlate with the idle.
>
>  
>
> The shop swapped in a computer from an automatic they had for sale and the
> car ran ok, although idle was consistently around 1100-1200.  The speed
> sensor code can also indicate a problem with the Motronic, so I got one from
> an automatic from Bruce at Audi^H^H^H^HGermanCarConnection.  Steve and Alex
> offered to help with swapping the chip.  However, the "new" automatic
> computer did the same as that from the five-speed, but it would reset itself
> without having the car turned off-probably a firmware difference.
>
>  
>
> My wrench had mentioned that he could never get his expensive diagnostic
> computer to talk to my ECU, but he had read and cleared the codes with a
> "cheaper" one.  Unbeknownst to me he now decided that with another ECU in
> hand the 5-speed box was not such a precious commodity, and he did get the
> fancy diagnostic computer to communicate by giving the original ECU a couple
> of love taps with the heel of his hand!  He cleared the codes and the car
> has now run well for several weeks.  It has idled once around 1200, but this
> might be the air conditioning?
>
>  
>
> Now all that's lacking is eerie music and a Rod Serling voiceover.
>
>  
>
> I'm hanging onto the other ECU just in case.  There's a chance that both
> computers have the same problem, but that seems unlikely.  Because some of
> the signals to the Motronic come from the IC, I wonder if there's something
> going on there.  Any differences between the 5-speed and automatic clusters,
> apart from the speedo constant?  I'd like to have spare parts or at least a
> chance of getting them before attempting the resolder fix.
>
>  
>
> Dave
>
> 91 5-speed
>
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