Ricks82

Last fall I purchased my 2010 GS with an eforce 1591, long tube headers and ls9 cam already installed. The car had cold start issues and P0116 codes. I found a local tuner and had him load the correct IAT tables (with help from members of this forum). So last fall everything went well. The car spent the winter on a lift, (cosmetic stuff) and on a battery maintainer. A couple of weeks ago I finally got the car out, and life was good (good starts and no codes). After 3 or 4 nice drives the p0116 code came back along with the cold start issue. From what I can read (internet, etc) pins 3 & 4 on my tmap (ford sensor) is for the IAT. Can I read the resistance across pins 3 & 4 and assume that is what it is what the ECM is reading. (since the tables refer to resistance)? If so my sensor reads good at ambient (53500 ohms at 54f). So I took this assumption a step farther and attached a 50k potentiometer across these leads to test readings at the ECM and here is what I came up with.
0 ohms=149f
10,000 ohms=51.8f
20,000 ohms=33.8f
30,000 ohms=23f
40,000 ohms=17.6f
50,000 ohms= 12.2f
So if this experiment is correct my readings match up with the Celsius scale not the Fahrenheit?
Am I on the right track? Any Ideas?
And to complicate things the tuner that I used last fall has turned to only heavy diesel tuning, and there's really no one in this part of Illinois.
Thanks for any ideas.
Rick

erick_e

Depending on your E-Force serial number, and which TMAP sensor you have it will vary.

You can get the IAT Sensor Curve at the website below; about 3/4 way down the page.

http://www.edelbrock.com/automotive/...scussion.shtml

Ricks82

I have the Ford TMAP sensor, and I'm using the tables from the Edelbrock website as my reference.

My main question is, Has anyone had their TMAP sensor fail on their Eforce SC, and am I correct in thinking the IAT is just a 2 wire sensor that I can replace with a known resistance for troubleshooting purposes?

Thanks

Ricks82

I'm thinnking about getting HP Tuners to help me figure this out. It looks like my other option is a 4 hour drive to a chicago area tuner.

Any thoughts??

Ricks82

I received my order of HP Tuner this week, and things are not getting an better?

Why does the ECM have 2 IAT tables? IAT Sensor Curve (Temp C) and IAT Sensor Curve 2 (Temp F)
I had noticed that the ambient IAT reading seemed to follow temperature C not F so I tried a little experiment. I loaded the IAT Sensor Curve 2 into both tables so that both tables have the Fahrenheit scale and that brings the ambient IAT and ECT to within 2 degrees.
Am I looking at a bad ECM?
I have tried a new IAT sensor.
I have checked the IAT tables.
I have checked as much of the harness as I can access.
Any ideas?
Thanks
Rick

erick_e

I wish I could help. I have had some issues with HP tuners and the Edelbrock calibration.

I don't think HP tuners can see/read all of the calibrations.

See my post below.

http://www.hptuners.com/forum/showth...-between-tunes

Ricks82

I wonder what the dangers are of running the car with the Fahrenheit scale loaded into both IAT tables? I haven't tried starting the car this way for fear of hurting it.
Thoughts?

DSteck

There's two IAT tables because some applications use a pre and post blower temp sensor.

Where are you located?

Ricks82

West central Illinois, kind of the middle of no where as far as tuners go.

realcanuk

Just looked at my tune and both tables are identical and set in Fahrenheit, using the numbers from edelbrocks site.

DSteck

West Central Illinois is pretty vague.

Do you personally have HPT?

Ricks82

Yes, just bought it last week. Still have a ton to learn.

Ricks82

That's good to know. If I can figure out what I need to log, I'll re-load both tables with the Fahrenheit scale and take it for a test run. For beginners see if the cold start is fixed.

Motorhead-47

You are barking up the wrong tree! A P0116 is a failure of the "Engine Coolant Temperature Sensor"....unrelated to your inlet air temps. A bad ECT sensor will definitely cause cold start problems. The ECT sensor is about a $20 part available at just about any parts house.



Unrelated to your problem but your TMAP (Temperature and Manifold Absolute Pressure) sensor is your only functioning IAT sensor on the car with the Edelbrock supercharger. Prior to the supercharger, the IAT measurement was in the MAF in the air bridge behind the air filter. With the install of the supercharger, your IAT measurement is no longer accomplished at the MAF. It is done at the TMAP only.

Ricks82

True, but my understanding of the P0116 is that it is primarily a compairison of the IAT and ECT on a cold start when both sensors should be reading ambient. If the 2 sensors don't agree within a certain percent the code is set.

I did load both tables with the degree F scale and the started great and went for a short drive. Now the start logging data and see how it looks.

Motorhead-47

I am very skeptical of your assessment on how the P0116 is set. I have never read nor seen anything that talks to the P0116 being tied to a temp delta between the IAT and ECT. Where did you get that information from?

If it were my car, I would first check the harness at the ECT and if it is fine, I would swap out the $20 part.

If you don't want to swap the $20 part, log your engine coolant temp sensor output and see what you have when the P0116 trips.

realcanuk

Have to agree. I have never seen anything about P0116 being related to IATS.

erick_e

Conditions for Setting the DTC P0116

• The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 30°C (54°F) greater than the IAT sensor.

OR

• The ECM detects a temperature difference at power-up that indicates that the ECT sensor is 10°C (18°F) greater than the IAT sensor, and the time spent cranking the engine is greater than 10 seconds, when the fuel level is greater than 5 percent.

OR

• With the power-up IAT greater than -7°C (+19°F), the ECM detects a temperature difference at power-up that indicates that the ECT sensor is 20°C (36°F) greater than the IAT sensor. Then the vehicle must be driven for greater than 6 minutes and 40 seconds at greater than 40 km/h (25 mph). If the IAT sensor then decreases greater than 4°C (7°F), an engine block heater was detected and the test is aborted. If the IAT sensor does not decrease, an engine block heater was not detected and DTC P0116 will set.

realcanuk

Cool. That's why I like the forums. Learn new things all the time. My list of code descriptions wasn't so detailed and didn't mention that.

Motorhead-47

Corvette service manual?