ACT sensor, to be or not to be?

the ACT is one of the most important sensors in calculating fuel delivery it NEEDS to be there.

Here is a discussion I wrote up on moving the ACT from the intake manifold to the air filter box...
http://www.freewebs.com/vristang/eecivfaqs.htm

If you have questions, feel free to ask...


Thumbing through the TwEECer (CalEdit) this is what can be seen...



In the X3Z Calibration

FN 825B - ACT will increase the engine idle rpm after about 192F, maxing out at 64rpm by 208F

FN 220 - EGR Multiplier is 0 until 58F, maxes out at 1 by 60F

FN 126 - Spark advance starts to retard at 160F maxing out at -2* by 190F

FN 135 - WOT spark advance is retarded starting at 150F, maxing out at -6* by 240F

FN 300 - Open Loop Fuel Multiplier is unaffected by ACT (always 1)

SCALAR - ACT MUST be between 100F and 200F for the Adaptive Strategy to start learning



In the A9L Calibration

FN 825B - ACT will increase the engine rpm by 48rpm at 200F, and a max of 72rpm at 226F

EGR Multiplier is .8 until 0F, then rises to a max of 1 by 56F

FN 126 - Spark advance starts to retard at 160F maxing out at -2* at 190F

FN 135 - WOT spark advance is retarded starting at 150F, maxing out at -6* by 240F

FN 300 - Open Loop Fuel Multiplier is .64 until -40F, .81 by 0F, and maxes out at 1 by 76F

SCALAR - ACT MUST be between 100F and 200F for the Adaptive Strategy to start learning



So what does this mean?

Idle speed – Obviously for both calibrations the affect is going to be minimal, assuming all other idle contributors are working properly. Moving the ACT to a cooler location should not have a major impact on idle speed.



EGR – Moving the ACT to a cooler location will affect the function of the EGR. It would not be recommended to try and pass an emissions test with the ACT in the airbox on a cold day (below 60F).



Spark – The Spark Advance is RETARDED with higher temps. Moving the ACT to the airbox can help to keep ignition timing higher. However, keep in mind that Ford used the ACT as a ‘Safety Factor’ for preventing high temp detonation. False information to the EEC-IV will make detonation more likely when the engine is warm/hot.



Fuel Multiplier – The Fuel Multiplier increases with higher ACT temps. Due to the low temps at which the ACT will impact the Fuel Multiplier this is not likely to cause an issue.



Adaptive Strategy – This may be the most critical one for most daily driver Mustangs. Not allowing the Adaptive Control to function (because the ACT never sees 100F in the airbox), could hurt fuel economy and could cause drivability issues.

Good info here in this old thread, ...just got code #54, ..cleared it and it came back, ....more money to sensors fund lol

Code 54 – ACT sensor out of range. Broken or damaged wiring, bad ACT sensor. Note that that if the outside air temp is below 50 degrees F that the test for the ACT can be in error.

Check the resistance of the black/white wire to battery ground. If it is less than 2 ohms, it is good. If it is more than 2 ohms, the black/white wire has bad connections or a broken wire. Always take resistance measurements with the circuit powered off.






See the graphic for the 10 pin connector circuit layout.


Then check the resistance of the ACT sender located in the #5 intake runner on most 5.0 stangs.

ACT & ECT test data:

The ACT & ECT have the same thermistor, so the table values are the same

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer. Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

Replaced gunky old one, idles very smooth now, cleared codes, system pass #11 ...back to normal operation.