Re: surging at cold idle

[Michael Zamikhovsky <MikeZ755@sprintmail.com>]

I had this problem on CIS-E3 in 87Coupe GT. At first I thought that air flow
meter plate was out of adjustment. While I was gearing up to adjusting it
over several months check engine light came on with knock sensor code. I
replaced knock sensor and surging disappeared.
MikeZ

Huw Powell wrote:

> the CIS-E is running fine but there is a surge at cold idle I would like
> to get sorted out.
>
> When starting, cold, for a moment the engine will hover at about 1k
> rpm.  Then it drops to around 700, and just as if I was tapping the gas
> pedal to prevent stalling, it will kick up to about 2k for a moment,
> gradually fall back to 1 k, stumble again, and repeat the cycle, with a
> lower and lower upkick, this continues for a minute or two.
>
> Any btdt's who remember what part was the culprit, what the fix was,
> etc.?
>
> Thnaks!
>
> (The actuator current cycles around 10 mA at warm idle, ISV duty cycle
> set to about 28 %, but this is with no hoses pulled and plugged.  Timing
> at about 20 deg BTDC.)
>
> --
> Huw Powell
>
> http://www.humanspeakers.com
>
> 82 Audi Coupe; 84 4kq; 85 Coupe GT
> http://www.nh.ultranet.com/~human