87.5 CGT Trip computer & MC swaps, do they get along?

[Huw Powell]

> So in summary, the orange digidash was used in 87.5 CGTs and later 
> urqs. .....   But
> for the most part, the orange digidash only needs speed and fuel level 
> to calculate fuel consumption and does not require either the airflow 
> pot OR the fuel enrichment signal from the ecu.  Neither is provided for 
> on the urq. 

There is no way to possible calculate fuel consumption (instantaneous, 
especially) without more inputs.  The trip computer must have some sort 
of engine load info in order to do the math.  I suspect it is just 
getting the data via a different path, ie, it's hooked up in some other 
way than the earlier ones.

As far as unused wires/connectors, I'd venture to say that *all* 
vehicles will have them - because complex harnesses are usually built to 
support a range of options.

Anyway, I still think there is no way you're going to get one of these 
old CIS trip computers to fully work after an EFI conversion.  On the 
later UrQ's which are EFI, the TC is surely getting air flow data from 
*somewhere* - probably the engine ECU, which gets it from some sort of 
sensor other than the old CIS airflow pot.

As far as the appropriate dash for an 87.5 (etc.) CGT, this could be 
useful info.  Though, I'd swear the one I have (87.5) is a red dash - 
and the TC works, as little as I've run it.  I'd go out and check in teh 
field now, except the temps just dropped below 0 F again... and won't be 
back up above that for a couple of days... brrrrrrr

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/