Hard start & rough idle when cold

[Bill Green]

As a devotee to your web site I did know to check and replace the "spare"
fuse. I also checked the ground connection on the intake manifold which was
fine. 

Speak of the devil I do have a spare used ECU on order which was too good a
price to pass up on ebay. I'll post back when it arrives and I install it.
Thanks!

-----Original Message-----
From: Huw Powell [mailto:audi at humanspeakers.com] 
Sent: Tuesday, February 09, 2010 1:25 PM
To: Bill Green
Cc: quattro at audifans.com
Subject: Re: Hard start & rough idle when cold



Bill Green wrote:
> 1985 4KQ with 2.2 L starts and idles fine when warm. But when trying to
> start cold it cranks longer than it should before starting and stumbles
and
> idles rough until it warms up. Once warm it idles and starts normally
> although the tachometer says it is idling at 950-1000rpm and no matter
what
> I do it won't go lower. 
> 
>  
> 
> I've checked for vacuum leaks and have found none, the air filter is new.
I
> checked the cold start valve and physically verified it was working. The
> coolant temp sender checks out fine as does thermal time switch. The O2
> sensor is new and reads .5v with very little fluctuation. The duty cycle
for
> the ISV reads 32% + 5% -0. Using Huw's adapter harness I found that the
> differential pressure regulator reads 15-16 milliamps when idling warmed
up.

The computer is not running the engine properly if the O2 voltage and 
DPR current are not fluctuating.

It's probably not doing any cold enrichment.

How is the ground on the intake manifold?  Has anyone pulled the "spare" 
fuse recently (it's for the computer...)?  Do you have a spare computer 
you can swap in?

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/