At 10:09 PM 5/8/2001, Alfred Bagdan wrote:
>When measuring the Temp I sensor during the rough running, the voltage is
>only about 0.5 to 0.8 Volts. Once I get the van running again with power, by
>restarting, the voltage is about 0.9 volts but still not what it should be
>for the temperatures here.

Ok, so the ECU is being told that the air is hotter, therefore less dense
than it really is, therefore less mass in a charge of air, therefore less
fuel is called for.  That would tend to make the mixture leaner, right?

>Also the O2 reading will go up above 1 volt and
>not cycle during the rough running.

Whereas this definitely indicates rich.

>  The Temp II sensor is as it should at
>about 0.125 volts when engine is hot.  AFM readings also check out.
>So I suspect it is the Temp I sensor that's on the fritz.  (What else could
>change the reading so drastically?)

Bad drive from the ECU?

>Anyway, pardon the lengthy description.

They're the best kind.

>Also, do I have to get a new AFM meter, or can one get the Temp I sensor
>independently?

I don't know for sure, but I have a nasty suspicion.

>If anyone cares to comment, please do. I will appreciate it.

I'd suggest unhooking the lambda sensor to see what effect that has and
what the reading is from it -- then get a resistance measurement from the
Temp I sensor when the problem is happening (have to disconnect the AFM and
go to the pins).  If the resistance is good (chart in Bentley, same as Temp
II) I'd think about trying a different ECU.  I might be very tempted to
take the existing ECU and reflow all the solder joints on general
principles, surprising how many things get fixed that way.

david

David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"