Re: Idle rough while engine is cold

["Jonas Karlsson" <jonas85k@hotmail.com>]

>From: Jeffrey Lowe <scirocco16v_1986@yahoo.com>
>
>My idle has been getting rough the past couple of days
>at start-up and while engine is still cold. I know
>there are probably a few dozen things that could be
>going wrong, but what should be some of my first
>things to look at?

I would look in 2 distinct areas. Slight airleaks when engine cold, and 
malfunctioning cold running stabilization system(s).

I'll start with airleaks, or more specifically, injector o-rings. When they 
get old, they shrink and get hard. When cold, unmetered air can leak by, and 
throw off the A/F ratio, and change idle. The ISV will try to compensate, 
and the idle will fluctuate. Once they get warm, they seal and the problem 
goes away.

The other thing is that CIS-basic, CIS-lambda, and CIS-E all have ways to 
stabilize cold running, and when they malfunction, cold idling will be 
rough. Check the coolant temp sensor and the cold start valve. A 
non-functional sensor/valve or interrupted electrical flow will render the 
system useless. Also the CIS-lambda/CIS-E brain has a temp sensor for the 
coolant so that when cold, the system runs open loop and enriches the 
mixture. Bentley describes tests for all of these systems. Take a look.

HTH, and let me know how it goes.


Jonas
85 Scirocco 2.0
78 Scirocco 1.8
For direct reply: jonas@metabolex.com
http://www.geocities.com/scirocco2l8v
________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com


--
Email problems to: scirocco-l-probs@scirocco.org  To unsubscibe send
"unsubscribe scirocco-l" in the message to majordomo@scirocco.org