mistamystery7

hey guys i need some help,
just got a new motor put in, and everything runs great except this cooling reading issue im having. my water temp (defi) gauge will read fine, when its up to about 80-90 degrees, the commander on the pfc will only read like 20 degrees, and i guess my car is therefore staying in a warmup mode? im assuming also running reallllly rich. i can see the gas gauge moving when drive for the most part, can smell it as well. the wierd thing is when you turn the car off the water temp gauge will start moving down while its cooling off, but then the commander will start going up in temp. any help would be appreciated so i can start actually driving this car and enjoying my new motor. thanks

allenhah

iTrader: (4)

You most likely need to replace the water temp sender...do a search on water temperature sesors...I think there are two: one that goes to the gauge in the dash, and another that goes to the ECU...you only need the one that goes to the ECU...I think it's the one located in the coolant fill area bc I know the one going to the driver's side of the engine is for the stock gauge.

When sensors go bad, they usually just start to read too low. Where is your Defi gauge reading from? Usually after shut off, you will get heat soak, so the stock sensor is actually reading correctly...just lower than it should.

Good luck!

mgoddard1

I think the water temp you see on the PFC is read by the sensor next to the oil pressure sending unit next to the spark plugs, not the sensor on the back side of the filler neck.

allenhah

iTrader: (4)

Hmm...I actually think it's the other way around. Check out THIS THREAD for info.

DaleClark

iTrader: (55)

The temp read by the PowerFC is the main ECU sender at the back of the water pump housing. The one by the oil pressure sender is JUST for the gauge in the dash.

I agree- replace that sucker. I don't think they're too spendy.

Dale

allenhah

iTrader: (4)

Exactly what Dale said ^

With most of our cars reaching the 12 year mark, various sensors and senders are simply getting too old and failing, especially with the ridiculous heat that they're exposed to. In my 93, I've had to replace the water temp sender to the stock gauge (the one by the oil pressure sender), and the intake air sensor in the last 3 months. Having a PFC is wonderful for these things! I never had to replace the water temp sensor behind the water pump (was probably replaced when I had the engine rebuilt about 3 times) but from what I've read, you probably need to remove the alternator and a little coolant to do the switch. There was also some talk of using the FC sensor for lower temp fan activation I think?

mgoddard1

I'll be damned! I really thought the water temp sensor for the ecu was the one next to the spark plugs. You learn something new every day I suppose.