Thanks to Tech, I went straight to the compensator to fix the broken temp gauge on my '90 245. Installed the jumper, and now the gauge works fine. And.... the car runs much better! I mean, quite a bit better, more power, etc. What's going on? Does the engine computer, when the gauge reads at the cold end (which it did when it was broken), cause the car to run differently?

monty

 

Not sure why it is running better.
It should not have any affect on the running of it at all.

 

Does anyone have any pics or details of this repair? I had no idea that you could fix the temp. gauge with a jumper. [&:]

 

IPD makes a kit, for $14.50, that provides a pre-made jumper and instructions. The instructions are found here: http://www.ipdusa.com/pdf/PI-297TempBypassKit.pdf

It's fairly easy to make a jumper and solder it on, or you can support IPD and buy theirs.

BTW, Tech: one detail that I left out in my original post above: the wire to the engine temp sensor was disconnected. If the sensor is connected to the computer, perhaps this is why I saw an improvement in performance? Did the computer always think that the car was cold?

If not, it's truly a mystery. We just drove it on a weekend trip, and it cruises at 85 mph without a hitch. Before, getting it up to 75 mph was a chore.

 

The single wire is for the guage only.
There is a 2 wire sensor for the computer.

 

Is there any need to do a similar mod on an '89 740? I know that my Saab had some type of circuit to keep the temp guage from moving much (generated false customer service concerns). Personally, I'd like to know exactly what's going on and if a jumper is beneficial, I'll add one. Obviously, my instrument cluster is totally different than the 240 series. I just added a volt meter (from a turbo model) and love it. Thanks.

 

It is different on the 740.