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View Full Version : 2.5 Air Temp Sensor Reading


Liqui-Fly
08-07-2002, 06:03 PM
Is 13K ohms at 75 degrees too much resistance for the temp sensor. ECU is analog and motor has very low EGT's.

David
Liqui-Fly
08-08-2002, 09:27 AM
Stupid book doesn't say what it's supposed to read and I realy don't want to bypass it but I will if you guys make me!!

David
pyro
08-08-2002, 12:30 PM
Not sure, but sounds high. If this is the same temp sensor they used on the 2.4 L Laser EFI's like mine, then 13K would be a reading on a warm Northern winter day! No wonder it's running too rich!

The service manual for a 2.4 says:

Air temp sensor should be approx. 8.5 K at 68* F, or 12K at 50*
Head temp sensor should be approx. 1.2 K at 68* F, or 2K at 50*
Liqui-Fly
08-08-2002, 01:00 PM
Got a part number for yours? I'll check and see if it matches up with mine. I don't think they'd be different. I'll short circuit the thing to see only if I have a good idea that it is high.

David
MERCMAN
08-08-2002, 10:26 PM
short circuiting will cause your box to go full rich
Liqui-Fly
08-09-2002, 07:36 AM
Open causes rich 10% and shorting it causes lean 10%.

David
pyro
08-09-2002, 08:05 AM
Short or low resistance is lean, open or high resistance is rich. If you disconnect either temp sensor, it should run richer at idle.

At least that's what I understood it to be...
MERCMAN
08-09-2002, 09:45 AM
once the box figures out theres a problem it will enrichen either way. that is if the reading it gets is too one extreme or another.
Liqui-Fly
08-09-2002, 09:52 AM
Guess my Mercury Service manual is wrong.

David
MERCMAN
08-09-2002, 12:02 PM
no , its not , if you read , low resistance , or high resistance it will change =/- 10 % not a dead short.
Liqui-Fly
08-09-2002, 12:08 PM
Do you know what a high reading is? I'm reading 13K ohms at about 78 degrees and don't know if that is high or within range.

David
captcarb
08-10-2002, 08:24 PM
get a new one!! It will make it run very rich.

Jim
Liqui-Fly
08-10-2002, 09:06 PM
Under divider gasket tips. Does that look rich hehe. I put it above a lighter today and it went down to around 6K ohms after a bit and went up to 18 K ohms in a glass of ice water. I'll pick one up. Thanks.

David
captcarb
08-10-2002, 09:16 PM
By the time I get the cowl off and measure it, it reads about 6K. Some people put a fixed resistor in while they are tuning. If you have EGT's watch them as the motor warms up. The sensor makes more difference than you might think.

Jim
Liqui-Fly
08-10-2002, 09:41 PM
I've been chasing my tail for a while. Starboard EGT is 990 and port is around 710 wide open. Motor has only been turning around 6500. Tore it down looking for a water leak last night. Didn't see really any evidence of that other than some black goo. Fuel was puddled up in the bottom intake ports and it wouldn't start tonight. Apparently flooded cause I had fuel and spark. Was running fine before the gasket changes. The only thing I can think is when I set it on the horn it all collected in the crankcase and need to be purged.....hopefully.

David