This type problem is almost always related to the O2 sensor circuit.
Does your sensor have the heat shield/deflector in place? Is the wiring
good? Is the O2 sensor heater working? The ECU tries to go closed loop
at ~120 and 1 minute running. If the O@ sensor output is not sufficient,
the ECU will keep richening the mixture to get the signal. If not
working, yet, it will go rich enough to choke the engine. Disconnect the
sensor for a test. If the problem stays away, then the problem is there.
When the sensor is disconnected, the leakage of the input circuit of
about .5 volt fools the ECU into thinking the mixture is ok so it does
not make any adjustment.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
Of Dylan Friedman
Sent: Saturday, February 07, 2004 10:07 AM
To: vanagon@GERRY.VANAGON.COM
Subject: ECU question

Hello List,
The patient is an 87 Syncro van, that has some hesitation after warm up.
I
have checked the grounds, ICV & ICU, temp sender and the AFM.  Still no
change.  If I turn off and reset the computer all seems to be fine for a
short period of time, but starts slight hesitation soon after.

My question is concerning the ECU computer.  How often do they good bad?
What is the best way to check it?

Can I rule out fuel delievery problems because it runs fine after a
reboot?

Thanks

dylan