88 80Q Won't idle when cold (Update)

[SJ]

> From: MXHOWES at aol.com
> Subject: 88 80Q Won't idle when cold (Update)
>
> 1. ISV operates freely when 12v is applied to it.
**** Ouch!   12 volts with no current limit can and will  burn out the ISV
windings.
The ISV works on a switching 12 v square wave signal - - - the average
voltage seen at the ISV is less than 12 V.
Use a 9v battery to do this check. The current from the small battery is
limited and cannot burn out the ISV windings.


> 2. If I disconnect the output hose (larger hose on side of valve, right?)
> and plug it, I can look at the ISV valve, during start up ands idle it
doesn't
> move (stays closed).
***** Yeah, this dont sound kosher.
Do Huw's idle switch test first. Make sure the idle switch is working.
Better yet, remove the idle switch connector and use a wire jumper at the
connector to make sure that the computer is seeing a short (closed
contacts).
When the idle switch is open (open throttle), the computer doesnt send any
signal to the ISV. At least, I dont think it does.

> 3. I preformed the fault memory output checks and the ISV didn't click
under
> code 4431 when the throttle switch was closed (the only one of these 4
tests
> which seemed to work was the cold start valve # 4443)??
> 4. If the wiring or connections from the FI Control unit to the ISV were
bad
> wouldn't I get a output code of 4431? There are no stored codes.
**** Cant help you here.

> It looks to me like the signal is not getting to ISV.
***** Seems so. But check the idle switch first before doing any more
testing.

I know that when I  did
> the heater core I had a great deal of difficulty in getting the FI harness
> plug back together (tight space, not enough extra cord slack to pull down
and
> hook the tab, but if I bent some pins I think I would have developed more
> troubles than what I have.
**** It's possible that a pin got bent or wire broke at a connector or in
the harness. The wires on the older cars get brittle and tend to break the
insulation and then the wire itself.
If you have the Bentley, you can locate and test the wire from connector to
connector to see if there is a break.
Dont forget that the break could be in the wire from the idle switch and not
the wire to the ISV.

Footnote: Keep the topic the same as when you first posted, with the "Re:"
added, otherwise it will be hard for someone later on to follow this thread.
When you find the answer to the problem, use same topic but add " - FIXED"
at the end of the topic line.

SJ



-- 
No virus found in this outgoing message.
Checked by AVG Free Edition.
Version: 7.1.408 / Virus Database: 268.13.4/476 - Release Date: 10/14/2006