Quote:
Originally Posted by mysocal911
So what! Just because it passes smog, doesn't imply that all functions within the DME ECM are fully functional.
Once the temp sensor is below about 200-300 ohms, the sensor has NO effect on the mixture.
Did you perform the test in post #4?
You indicate; "won't hold idle for a few minutes when cold", then fully disconnect the temp sensor when cold to check for a mixture problem.
If the startup idle improves, then the overall mixture is too lean. Your measurement of the O2 sensor when warm of .27 volts
indicates a LEAN mixture which can cause a low idle when cold. You can push on the AFM flap to richen the mixture when cold to check for an idle improvement.
Your problem isn't that difficult to solve! A 911 3.2 DME engine running problem is extremely simple to troubleshoot.
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Since it is easy enough to debug the temp sensor, I did that first. It does seem to be a potential culprit. I disconnect it and leave it dangling, won't hold idle. Jumper with a 2.7K resistor, engine will hold an idle although not super smooth and a bit low RPM, but at least it stays running. When I pull the jumper it dies.
Tried a 270 Ohm resistor and a wire to short it completely, neither will get it to hold an idle.
Ugh, it's a bit of a pain to replace that sensor so I'd really like to make sure it's the problem. Again, when I measure the resistance across it when it's cold, I get something less than 2K Ohms. I'll take a few measurements when the engine warms up and see if it is showing at least some response to the engine temp. If the mixture is off due to some other cause is it possible I see the above behavior?