Wont rev above 1500 RPM then coold

[Huw Powell]

> Bought a not so new car a while a go: Audi Coupe, 90 2.3E (KE III
> Jetronic). It has been messed with, probably allot... It's giving me a
> headage.
>
> It wont get above ~1500 RPM then cold (about 15C outside right now),
> sounds like it cuts of the fuel then it gets close.

That sounds to me like an idle switch staying closed.  One thing the ECU
does when the idle switch is closed (ie, foot off pedal) is kill the
fuel for a moment if the engine is above about 1400 rpm.  This saves
fuel when you take your foot off the gas.

The idle switch is under the throttle body, and is part of a little
assembly that includes the wide open throttle (WOT) switch, which is
mounted on top.  Their wires come together and meet in one three pin
connector.

Start by unplugging that connector and measuring the idle switch
resistance in open and closed positions...

> I have adjusted the current to the pressure acurator (was way of, ~18 -
> 22 mA, warm engine), it's now -2 to 5 or there about, that fixed allot
> of bad behavior, but not the problem above.

It is supposed to *fluctuate* around 10 mA, not sit steady.  If it is
steady when warm, your OXS may be bad, or something isn't hooked up right.

 > I checked the temp. sensor
> on top of the radiator hose flange. It works, (but I don't know if it
> works _right_: about 1.78 ohm at ~70C and 0.48 at 90C).

Remove it and test it in ice water and boiling water to check if its
range is close to right.  I forget the specs right now, they are in the
Bentley shop manual though.  It does sound a bit low form what I recall,
though - I think it is supposed to be around 1500-2000 ohms when cold
and drop to 150-200 ohms at operating temp.

They are pretty cheap, and I would tend to go with the recommendation of
soe that you simply replace it with a new one on general principles.

Have fun, and good luck!

--
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/