Horrible idle after CAS replacement

[jccjr1982]

Hey everyone... I had this problem for a while...

One day, my CAS went out on me. The shop replaced it, but after they did that my idle *consistently* fluctuates (about 100 rpms). Nothing erratic, just a consistent fluctuation that makes my exhaust noise stand out.


I took the car back to the shop, and they checked the timing in my presence, and all the marks line up.
I did a Boost leak check; passes.
I had a 255lph fuel pump in it at the time of the CAS replacement, but I switched it out back to the stock fuel pump and car still acts the same.
Visually inspected all the hoses, all appear fine. (none obvious cracked/broken)
Switched out my plug wires with another set, problem still exists.
Spark plugs visually appear fine.



**Please note that the car cruises and drives fine...**, the idle only fluctuates after warming up and when no pressure is applied to the gas pedal (to emphasize, if I shift in netural while going 60 mph, the tach fluctuates just as if the vehicle is at a complete stand still) .

 

[ROOKIE1]

Was the cas aligned when they installed it ?

 

[jccjr1982]

Hey I know this is an ancient thread, but I'm still having this issue. I searched for new insight on idle issues posted recently, but have found none. The car has been taking my reserved parking space all this time. Tried to get ANOTHER red permit, but thanks to the new California DMV rules this year, I MUST smog the car, and pay a $50 fee for any subsequent red driving permits (if car fails smog). No more trips to the DMV with the saying "oh I have parts on order" and them just handing out the red permits like candy.

 

[jayb903]

I feel your pain. Not trying to jack your thread but I'm having the same problem it feels like I hope to get some insight on this as well. C'mon people lets try to get this guys' car back on the road.

 

[DSM_PWR]

WOW WTF
After 2 years still havent found the problem?...

*When you did the boost leak test, did you use soapy water to visually check for leaks?
*Have you tried using maybe a local's ECU?
*Have you checked Base Timing?

 

[jccjr1982]

WOW WTF
After 2 years still havent found the problem?...

*When you did the boost leak test, did you use soapy water to visually check for leaks?
*Have you tried using maybe a local's ECU?
*Have you checked Base Timing?

1: Yes, I remember spraying tons of soapy water everywhere where needed, and I discovered I had a leaky BOV around the vent holes (I know, I know.. bad), but I put the stock on back on, problem still exists. On the subject of leaks... I also remember I had a vacuum leak around the BISS, but I put some sealant on it to stop that.

2: I am a DSM loner

3: When I took the car back to the shop to complain (since my car didn't have this issue before they fixed the CAS), they checked the timing with me present, brought the light gun out, removed the wheel, and showed me the timing marks which lined up.

 

[DSM_PWR]

Hmm.. if its just the idle thats giving you the problem, possibly the ISC.

Try unplugging it and seeing if it makes a difference during idle

 

[eoseitz]

I actually have the exact same issue. Not stealing the thread, just interested in any suggestions as well. What will unplugging the ISC do? Does it use a generic air/fuel map or something?