Is there more than one temp sensor on a 1993 240? I have an erratic guage in the dash and a hard and rough running engine (until it runs for a few minutes) when it is cold. I think I need a new temp sensor, but want to replace the correct one for the hard starting problem.Are the guage problem and the hard cold starting the same problem, or at least related?

Jim

 

Yes there is 2 of them.
The guage one is a single wire.

 

Hi Forum,
I've been posting about a high and surging idle issue with my 1993 240.
Now it's also a starter issue and i'm interested to follow up on the coolant sensors.
I have done a thorough PCV and intake service. Removed and thoroughly cleaning intake manifold, all components, new Bosch Idle air control valve, new fuel pressure regulator, rebuilt the injectors, new oil separator and flame trap and hoses, cleaned MAFn ew vacuum lines where needed.
I needed a new battery to get it started and the starter needed a few taps at first. Then started quickly and strong for 2 days.
This morning I ran through the fault codes, for ECU, LH- 2.4 fuel system, EZ-116K ignition system, none to be found.
OOps, now the starter would not engage! I tried tapping, but no go , yet. Likely I will replace the starter, again.
I am NOT finding the condition that would indicate a faulty coolant temp sensor.
BUT my idle gradually rises after a cold start to a high level. It can move the car on flat at 10 mph! It has a periodic short lowering but very short and then back up high.
HELP!

 

Searching through the manual I see the tests for MAF. I know some have pointed to that component as the culplrit in high idle issues on this model. I will do those electrical tests and see if that unit fails.

 

Because others have replaced the MAF only to report it did not solve the idle issues I hope some of you will continue to send tips. Same with the coolant temp sensor. My onboard diagnostic did not show a fault for that.