More info on cold start problem '90 200tqa

[Frank de Kat]

I once had a very hard time starting my 4000q when cold..

On investigation, I found that both wires to the cold start injector had
been broken.
That doesn't sound like your problem.

I also found that the coolant temperature sensor had gone bad, making the
computer think that the motor was always at operating temperature. The
symptoms were that it was hard to start, and 'stumbled' a lot when the
throttle was opened suddenly.
I got onto this when thinking that it was acting exactly like a manually
activated choke motor does, when you forget to put the choke on when starting.
Actually, replacing the sensor made much more of an improvement in the
starting than fixing the cold start system did. And it's relatively easy to
check the resistance value of the sensor.




At 10:24 AM 8/6/02, you wrote:
>Ok, this morning (thanx to Huw's sage advice, taking the time to answer
>my newbie questions) I pulled the connector for the cold start valve and
>looked for GROUND at the appropriate terminal - gr/wht wire IIRC -
>during cranking.
>
>I found ground for a *fraction* of a second when cranking first begins,
>and then a relatively solid ground for a second or so when the car acts
>as tho it is going to start, but no ground during actual cranking.  Does
>this sound right?
>
>Again, symptoms are crank, kinda-sorta attempt to fire, crank for time
>eternal.  MUST stop cranking, sit, wait and repeat, each time w/improved
>suceess until car will idle.  It's during the "kinda-sorta attempt to
>fire" that I saw ground for the CSV.  Everything I've read seems to
>indicate it should ground during cranking..........?
>
>Of course I realize this is temp dependent; car had been sitting all
>night, I'd say outside ambient temp was approx 50-55 degrees, but it
>will exhibit the same "cold-start" symptoms after sitting for 4+ hours
>in 90 degree heat.
>
>Thanx for any replies, I'm determined to figure this out, 'cause if I
>can't I won't keep the car, it nearly sends me into fits of rage when it
>does this :(
>
>Next step is to look at morning fuel pressure/fuel accumulator/check
>valve as some have suggested.
>
>TIA
>Keith L


Frank de Kat
fdekat at sentex.net
Dundas, Ontario, Canada

Audi 4000CSq (x2 !)
http://www.sentex.net/~fdekat
(To see "The Rally Pictures")