I was having problems with the CIS system in my 83 245T wagon back in November. The original problem was that the car would not idle when cold. All signals going to the ECU seemed correct, and the air control valve and throttle switch were both in good working order.

I got my hands on another CIS ECU, swapped out the questionable one, and the car idles beautifully now. I have included my original post for documentation, but just wanted to share the solution and thank those of you from the board that offered all the good advice.

-Scott

Sorry for the double post...meant to post this in the 200 forum, where the help came from...

>>>>>>>>>ORIGINAL POST<<<<<<<<<<<

My 83 245T won't idle when the engine is cold. Warm idling works fine.
I have done a lot of research on the CIS system in the car, and have followed the procedure in this document:
http://oregonstate.edu/%7Eerdts/kjet/docs_green.html
as well as the bentley manual, at least related to the electrical parts. I have not done a vacuum test or cleaned the throttle body, which may be the problem. However, when testing the system electrically, everything seems fine:
1. coolant temp sensor increases resistance with decreasing temp as read at ECU
2. The throttle switch is working properly as read at the ECU
3. When I connect pins 5 to 2 and 4 to 1 on the ECU, the air control valve opens completely, sending engine speed up to 2500RPMs

When I ground the test wire (blue/white), nothing changes to the idle speed (no decrease in engine speed when warm).

What would be the next logical step for me to take here? Clean the air control valve or throttle body or something else? It seems that the ACV should be working, when tested it did respond... Since all the electrical systems seem to be in good working order, could it be the ECU?

Thanks for getting back to us with the solution. I am glad all is well.

Mario
--
82 242 DL-MPG

You know I have been having the same problem and have not been able to figure it out, but thanks to you I may be able to fix it now. The only questions I have are how much did you pay for the ECU, and was it hard to replace? I have an 82 245 and I cant get the idle to work right when the temp is above 30 degrees, but if it in the 20's it high idles and runs rough but it does run. But I still have a rough idle that I think may be the throttle body being dirty. I really want to get this fixed so if you have more info about what happened to your car it would be great. My Aux air valve works fine and has been cleaned.

Here's a list of what I and a volvo shop have done,

New coolant temp sensor-Me
New injectors-Me
New injector o-rings inner and outer-Me
Idle set-The shop
Fuel air mixture set-The shop
New o2 sensor-Me
Multiple tune ups-Me
New exhuast manifold gaskets-Me
New flame trap-The shop

I love this car but I hate the crap it puts me through, and that shop charged me 200 dollars to tell me that the o2 sensor was bad and the flame trap had popped off. Plus another 175 bucks to set the mixture, the idle and to replace the flame trap, so as you can tell I am pretty much on my own with this car and I am at my wits end. Any help you or anyone else can throw at me would just be awsome, thanks everyone.

I bought a second wagon to be on the receiving end of a motor swap I am planning from my original 83. I used the ECU from the "new" car to see if my idle problem would be solved when I did the swap. I'm told you should be able to find ECUs at junkyards fairly easily, but how to tell if it works, I'm not sure. I think I just got lucky.

I think your situation is different than mine, since my CIS system wasn't doing anything at all. I had to hold my foot on the gas until the car was warm, then it would idle normally (at any ambient temp).

The ECU is easy to get to (and replace, if you feel you need to). It's right behind the passenger right-side kick panel. There are two connectors to it...you pull them off to perform the tests. I would really recommend reading this document:

http://oregonstate.edu/%7Eerdts/kjet/files/greenbook_CIS_System_1981_TP30363_2.pdf

It goes through a step-by-step procedure for diagosing the CIS system. You'll need a voltmeter and some extra wire to use as jumpers, but this method allows you to read what the coolant temp sensor is sending to the ECU and whether the air control valve responds to ECU output (by shorting two pins on the connector).

Hope this helps. Good luck!

I have to hold my foot in it also or it will bog down and try to die, it sounds a lot like the same problem but I will trouble shoot it and see what I turn up thanks a lot.

Ps that website is awsome thanks alot.