Hey Guys ~

I'm still trying to get Goldie up to speed (89 240 that a previous owner installed a turbo from a 740 in).

I'm getting abysmal mileage (15-17 highway), and it often hesitates not only on acceleration, but sometimes as I'm just driving highway speed. Also, my temp gauge fluctuates pretty wildly.

From everything I've read here, I'm thinking I need to replace my temp sensor(s).

I understand that there are two of them - one for the gauge and one for the ECU. But from other things you guys have said, I'm led to believe that they kind of work "in tandem."

Do I replace BOTH sensors at the same time?

Also, do any of you have a great link-up for buying them? I can get them at OReilly's, but I'm not sure they sell the best ones, or for the best price.


What would y'all suggest? Thanks!

 

I would worry about getting a handle on the engine temp first. I would try this first from Art Bestein's website (costs only time) and a bit of wire. http://cleanflametrap.com/tempFaker.html. This might settle down the temp gauge fluctuations, wildly fluctuating sounds like a feature of the temp compensation board failure. I suspect you have may have more than one problem. I would want to make sure the temp gauge is accurate.

Has the Oxygen sensor been replaced? that would be a player for the mileage problem.

Of course having a turbo at my disposal, would encourage me to be a bit heavy with the long skinny pedal, thus making the MPG's diminish.

Good Luck and post back with what you find.

Fred

 

Yes, I have a new O2 Sensor. I've checked every vacuum line & connection I can check, and found nothing leaking (all my interior baffles work correctly, leading me to believe I don't have a vacuum leak).

I should clarify about the temp gauge... The needle does not flutter or swing like a pendulum. What I mean is that it will slowly creep up toward the red - which initially really alarmed me. Then it will slowly move down almost to "cold." Sometimes it's steady.

I'd think it was the thermostat, except that the cabin temp never changes after the car is warmed up. I'm also not loosing coolant. When I've stopped & looked under the hood - when the temp gauge is near red - there is no steam or indications of a hot system. I've got the auxiliary cooling fan on a toggle switch, and when I turn it on the temp gauge doesn't change.

So I'm thinking temp sensors. Am I wrong?

 

I would bypass the temperature compensation board and maybe replace the thermostat. The ohms of the ECU temp sensor can be checked with a ohm meter, I would measure it before replacing it.

 

I found the following information in the Volvo Pocket Databook for Cars for the ECU Temp sensor (ECT) PN 1346030. I checked this PN at Tasca.com and FCP they both indicate this is the sensor used for the ECU

-10 degrees C/ 14 F 8200-10600 ohms
+20 degrees C/ 68 F 2200-2800 ohms
+80 degrees C/ 176 F 250-450 ohms

I hope this helps.

Fred