Any CIS-E III experts?

[Huw Powell]

> Ok guys, my saga with the new 88 90Q continues.
> 
> Massive intake leaks found and fixed (warped intake manifold if you would
> believe it was one of them)
> 
> New O2, coolant temp sensors (both)
> 
> Timing belt, cap, rotor, wires, plugs, ignition timing dead on.
> 
> Sounds like it should run like a top now, right?  Nope, 2 codes left:
> 
> Wide Open Full Throttle Switch
> 
> Mass Air Flow
> 
> The throttle switch has to be in the wiring or the brain itself, all tests
> check out per the bentley, but the ECU does think the full throttle switch
> is being triggered constantly. 

Checking this is going to be a pita, since the ECU is stuffed up in 
front of the air box, forward of the glove compartment.  But, get to it, 
unplug it, and measure the wiring to the WOT switch to see if it's the 
problem.

I'd also triple check that switch to make sure you're measuring it 
correctly.

> The Air flow error really sucks, those potentiometers should not be messed
> with and are EXPENSIVE.  Same unit used on VWs CIS-E Motronic...had my
> nightmares with those.

Again, measure twice, cut once.  Unplug the potentiometer, fashion some 
sort of harness or wiring to it, and measure it's resistance (center to 
top and/or bottom) while slowly raising the air plate.  It should change 
smoothly, with no dead spots, etc.

If it is bad, a used fuel distributor assembly shouldn't be too horribly 
expensive.

> So, my questions:
> 
> Anyone run into the full switch senario before, even though the switches
> all check out?  What did you do to solve?  I'm about to unplug the ECU and
> start checking continuity at the pins to the connector at the TB.

I've had idle/wot switches go bad, replacement is a pretty effective 
cure.  I've also seen wiring go bad one way or another, but not in a 
long time.

> The Mass Airflow....my mechanic (whom so graciously "assists" me in my
> work at his shop) suggests I ditch the CIS-E III infavor of the older,
> simpler CIS-E from say a Quantum Syncro.  He believes we can just swap the
> fuel dist and plug in the Quantum ECU to the CIS-E III harness and it will
> work perfectly.

No harm in letting him try - as long as he owns the parts, not you.

> Anyone done it?  Can you verify we won't have to swap the
> whole wiring harness?

Not that I know of, although the CIS-E system will run that motor 
(observed from 2.3 swaps into 4kqs)

> Considering that potentiometer is NOT a seperate
> replaceable part and you have to order the whole bottom half of the air
> flow sensor plate, at $600, I am very interested in ditching this stupid
> system.

You mean installing an aftermarket EFI system?

> CIS-E is knock sensing and has been used on 10:1 motors long before CIS-E
> III was used.  Main difference between CIS-E and CIS-E III is the
> potentiometer and its associated programming. IE, that is the only thing
> added I can find.

Thanks for adding those errors so authoritatively to the archives.

> My question was specific, can I plug the CIS-E brain into the CIS-E III
> wiring and have it work properly.  Not if this was a good idea. (thanks
> for your opinion though).

All you have to do is compare the pinouts in the respective Bentley 
manuals... which, considering that they have different numbers of pins, 
means...

No.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/