[T3] Bad day at the (FI) office

Jim Adney jadney at VWType3.org
Sat Mar 19 18:51:05 PDT 2016

On 19 Mar 2016 at 17:32, Daniel Nohejl wrote:

> So here´s a little update on our drivability situation!

> We pulled into a gas station and installed an A/B brain from Jim¦..A/B
> because itTMs not 100% clear what the CU10X on the Bosch rebuild sticker
> means. For now, that seems to have cleared everything up as we put on
> another 18 miles and had no bucking, hesitation, or dips in idle speed.
> It drove and idled steadily. 

That sounds promising, but I'm sure we all understand that you'll 
want quite a bit more experience with this before you're sure you 
have a solution. While you were exchanging brains, did you check the 
edge connector tightness with the little piece of PC board I sent 
you? A loose connection there would also explain how your problems 
seem to come and go, and how they often seem to get "fixed" by a 
change of brains.

> I wonder if the process of failing and the ultimate failure of the
> ground connection for the brain caused something else to fail within
> the brain? I have no idea how they work so I won´t embarrass myself by
> trying to theorize about what may have happened. 

Without the main ground, the only grounds to the system are via the 
low impedances of the injectors and the cyl head temp sensor. I've 
looked at the schematic and my impression is that this would either 
cause permanent damage or no damage but not intermittent failure.

Hang onto the extra brains you have there until you're satisfied with 
at least one of them. Eventually, I'd like you to test each of them 
and mark them with your results, so I have a better idea of what I'm 
getting back.

Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA

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