jackballs529

When reading engine temp through TunerPro RT, does the info. come from the CTS or somewhere else. Just trying to rule out a bad CTS.

BigBadLou

iTrader: (3)

Yes, the info comes from the ECM that interprets the electrical signal from the CTS in degrees of C or F.
If you have a dirty/corroded/oxidized connection on your CTS or a short in the wires, that will affect the reading as well.

Before replacing the CTS, check the resistance on it when cold and warm to see if it is right or not. A search will reveal the resistance values for a CTS.

Lou

jackballs529

Thanks for the info. So am I safe to assume that if dataloging the temp from the car looks accurate, the CTS is working good?

BigBadLou

iTrader: (3)

If it looks correct, it most likely is.

Lou

GregWestphal

iTrader: (1)

No, the temp gauge for the dashboard uses a different sensor than the one for the ECM.

jackballs529

Greg - I understand that, but I am not reading from the dash. I am reading through ALDL and my laptop which gets its info. from ECM.

BigBadLou

iTrader: (3)

Jackballs, what is primary the purpose of your question? Is your car not running right and you're trying to maybe identify a possibly bad sensor? If so, make sure your IAT/MAT sensor is reading correctly. It influences the mixture extremely. Mine would read 56*F (on a 100* day) and I was running rich as hell.

Lou

jackballs529

Car idles like it has a miss and stalls under load, stinks bad like fuel (Rich). Which sensors are IAT/MAT? Where would the readings broadcast on TunerProRT. I am getting back into working on/tuning my TPI after a couple years so I am a little rusty.

BigBadLou

iTrader: (3)

The IAT (Intake Air Temperature) sensor is also called MAT (Manifold Air Temperature). The readings would be probably under Air Temp or Air Charge Temp or something similar.

The sensor is located on the "underbelly" of the stock TPI upper plenum, towards the back. It's very hard to reach but if you just want to measure its resistance, you can unhook the tan/blk connector (C121) on the back of the driver side valve cover and measure it there.

If you have low readings from a temperature sensor (if it reads too low - and a disconnected sensor would read -58*F), you would get a badly rich condition and that would cause stumble, miss, hesitation ... simply an overly rich condition. I had that problem on my Z28, the IAT sensor was reading 56*F on a 100-degree day.

Another problem I had was on my Cougar engine where the injectors were so old that they were flowing +/- 20% and the O2 sensor readings were throwing off the ECM so much that it was running very rich and causing stumble, hesitation, miss etc. You can flow test your injectors at home, very easily. But you need to take the whole TPI off.

Lou

jackballs529

Thanks for the info, I will check that. I have a Superram which is a nightmare to take off, I just had it off and installed Ford 24# injectors a few weeks ago. I might be able to take that sensor out without pulling the intake.

BigBadLou

iTrader: (3)

No need to take the sensor out completely. As I mentioned earlier, you just need to measure its resistance at certain temperatures. To do that, you can just disconnect C121 and measure there (see my post above).

Measure the resistance with cold engine and hot engine. Look up the resistance and corresponding temperature in the table here and that will tell you if the sensor is bad.

Lou

jackballs529

Just looked at TunerProRT here at work and saw this:

Manifold Air Temperature (MAT)

So as long as I watch that, I will know exactly what the senser is reading.

Thanks again, I will give it a shot.

jackballs529

CTS is working fine. Watched it go fro 65 degrees and up as engine temp increased. BLM was 114. I may have to tune around the problem until next spring. Out of time and money now...