940 searching idle in cold weather

Amys 940 · Post by **Amys 940** » 11 Mar 2012, 09:03

Hi everyone. New to the forum and definitely enjoying the wealth of info! I have a 94' 940 non-turbo that's been great to our family and now has 208k on it. In the cold weather of winter, when I start the car, the idle goes up and down rhythmically. If I put it in gear too quickly, it can actually stall. This condition only seems to last about a minute. Wonder what it may be? Does this engine have one of those PCV traps that gets clogged? Idle air valve problem? Wondering where that valve is on this car? Doesn't seem to be built into the throttle body. Is it remote and run in with vac lines? Any help would be appreciated.

Post by **regent** » 11 Mar 2012, 10:01

Wlcome aboard, Amys 940
Start with cleaning your MAF sensor and ICV (check out the attachment for location of that hidden Idle CTRL)

Amys 940 · Post by **Amys 940** » 11 Mar 2012, 21:26

Thanks for the info! I really ought to take my idle air control out and clean it. I notice that I don't really have what looks to be the normal MAF sensor though. Mine is very small and looks to be a standard intake air temp sensor. Kind of weird. Anyone know anything about this? Please let me know. Thanks again. What a great forum!!

Post by **regent** » 12 Mar 2012, 08:22

There should be a MAF meter to provide the air mass and air temp signals to the fuel CTRL system; it is usually located on or after the air box. There is also a Manifold Pressure Sensor on the intake.

Amys 940 · Post by **Amys 940** » 12 Mar 2012, 18:03

Yea, my car is kind of different from all the pics I see. The only thing in the entire air boot is a small two wire sensor. Nothing like the MAFs I've seen on other cars?? Trying to attach a pic. Took the IAC off and cleaned it out. We'll see tomorrow if that fixed the cold idle searching.

Post by **regent** » 12 Mar 2012, 18:29

Take that back. It is a temp sensor.

Post by **regent** » 12 Mar 2012, 19:21

On the 940 wiring diagrams, the fuel injection system types are shown on pages 28 through 33.
First, determine which fuel control system your car has, and then see if you can locate the MAF sensor (device 7/17 with a 6-pin connector on the prints); its physical location will depend on the type your fuel injection system. Also, the MAP sensor (Manifold Pressure) is device 7/50.

URL: https://www.matthewsvolvosite.com/downlo ... iagram.pdf

Hope this helps

Amys 940 · Post by **Amys 940** » 12 Mar 2012, 19:29

Any idea, then, how my car manages it's basic fuel control? I don't see a MAP sensor either. I'm sure the TPS has something to do with it. Older GM cars relied more heavily on O2 sensors for primary fuel control, but all other cars I know use them as a trimming device only. Wonder why my car seems to be a little different than other 94' 940s?

Amys 940 · Post by **Amys 940** » 12 Mar 2012, 19:33

Wow! Think I was writing as you were. Thanks for the great diagrams. I'll check them out now.

Amys 940 · Post by **Amys 940** » 12 Mar 2012, 21:53

Ok, it's definitely a Regina Fuel injection set-up but none of the 3 ignition systems seem to match mine. The closest is the Rex. The trouble is that I have a standard, plain-Jane distributor cap just under, and in front of the intake. Neither of the 3 systems show this type of distributor. However, the rest of the components, or lack thereof, seem to match the Rex. Do you happen to have the description and operation of the Rex/Regina systems? Thanks!