cold engine ? and ect sensor index

DDSTANG94 · May 2, 2009

does the ECT sensor need to be indexed or put in a certain amount?

also what can cause poor performance when the motor is cold, here is what has been replaced

ECT
O2's
tune up

what eles could cuase problems? the problems im experiencing are at low rpms when the motor is cold it feels like the timming is retarded and skips a little bit, then when it hits like 3k it comes alive and starts pulling harder, like i said it does it when its cold out and the motor is cold

DDSTANG94 · May 3, 2009

common guys ??

cjones · May 3, 2009

IAT (Intake Air Temp) - if that shows warm air coming in then it could cause problems. when you replaced the ECT you replaced the coolant sensor with 2 wires, right??

have you run codes??

DDSTANG94 · May 5, 2009

cjones said:
IAT (Intake Air Temp) - if that shows warm air coming in then it could cause problems. when you replaced the ECT you replaced the coolant sensor with 2 wires, right??

have you run codes??

ok is the IAT different from the ACT? when i replacet the ect i only did the one that treads in the intake fitting.....and yes but no codes came up

HISSIN50 · May 5, 2009

IAT and ACT perform the same function. They both measure the temp of the intake charge. Fox III's (with intake mounted sensors) generally are called ACT's. Cars with the sensor in the air inlet tract seem to be called IAT.

The ECT is the coolant sensor for the EEC.

You dont index an ECT.

You dont have to index an IAT but I do (I put the support posts at 12 and 6 o'clock so nothing blocks the bulb).

DDSTANG94 · May 5, 2009

HISSIN50 said:
IAT and ACT perform the same function. They both measure the temp of the intake charge. Fox III's (with intake mounted sensors) generally are called ACT's. Cars with the sensor in the air inlet tract seem to be called IAT.

The ECT is the coolant sensor for the EEC.

You dont index an ECT.

You dont have to index an IAT but I do (I put the support posts at 12 and 6 o'clock so nothing blocks the bulb).

ok thanks, any thoughts on what my problem could be?

HISSIN50 · May 5, 2009

Have you checked codes and the calibration of the ECT?

toyman · May 5, 2009

From reading the posts I don't get a clear picture that the OP knows where the ECT is located. It appears that he's confusing it with the IAT (ACT). The ECT is located on the passenger side lower intake manifold and has a two wire connector. The coolant sensor on the driver's is the one for the dash gauge and has a single wire.

DDSTANG94 · May 6, 2009

HISSIN50 said:
Have you checked codes and the calibration of the ECT?

no codes, the ect is brand new motorcrafter

HISSIN50 · May 6, 2009

Being new doesnt mean good, nor does it mean the sensor is calibrated. You just gotta test it (I would ohm out a new sensor before installing it, just for the sake of doing so). With it on the car, I'd check the signal reading instead - since that takes the voltage to the sensor into account.

DDSTANG94 · May 15, 2009

HISSIN50 said:
Being new doesnt mean good, nor does it mean the sensor is calibrated. You just gotta test it (I would ohm out a new sensor before installing it, just for the sake of doing so). With it on the car, I'd check the signal reading instead - since that takes the voltage to the sensor into account.

iv had two new ect's on there, how exactly do i check it

HISSIN50 · May 15, 2009

The IAT is scaled the same as the ECT.

ECT values

Dino Dino Bambino · May 15, 2009

IAT sensor = Intake Air Temperature sensor = ACT sensor = Air Charge Temperature sensor (located in airpipe between MAF and TB)
ECT sensor = Engine Coolant Temperature sensor (located on passenger side of intake manifold, screwed into heater tube assembly and has 2-wire connector)
Coolant temp. gauge sending unit is located on the driver's side of the intake manifold and has a single-wire connector.

The engine needs a richer A/F mixture and more timing advance when it's cold, so the ACT and ECT sensors are very important during the engine warm-up phase. If there's a short in the wiring to either of them (or a short inside the sensor itself), the voltage across the sensor wires will be near to zero volts (too low) and the engine computer will think that the engine's hot, retarding the timing and leaning out the A/F mixture causing cold driveability problems. I suspect your problem lies there. A short in the ECT sensor wiring will usually cause the electric fan to stay on constantly while the engine's running.
If either of the sensors themselves goes bad, the result is usually the opposite (voltage across the sensor wires near 5.0v reference, engine runs rich but otherwise pretty well during the warm-up phase).

HISSIN50 · May 15, 2009

IIRC, as IAT and ECT values increase (towards VREF), the indicated temperature is lower, not higher.

Dino Dino Bambino · May 15, 2009

You're quite right Hissin. Thanks. I've corrected my last post.

DDSTANG94 · May 15, 2009

so is it possibly it is the IAT or more likely the ect

HISSIN50 · May 15, 2009

DDSTANG94 said:
so is it possibly it is the IAT or more likely the ect

The ECT is more important IMHO.

But test both. It will take just a minute to test each. I do them at room temp and then at operating temp. Those are two critical temps and are spread wide apart. If both are copacetic, I can assume any interpolations or extrapolations will be copacetic.

DDSTANG94 · May 17, 2009

HISSIN50 said:
The IAT is scaled the same as the ECT.

ECT values

ok so i tested the ECT at room temp in my house, about 70*. I put the meter at 200k ohms and got 22.7X so my sensor is no good? what should it read at that temp..did i do it write??

HISSIN50 · May 17, 2009

Seems a little off. It should have read somewhere near 38K Ohms. Was the bulb sitting in water that was room temp? I dont test the sensors in free air so I'm not sure if that could affect it.

DDSTANG94 · May 18, 2009

HISSIN50 said:
Seems a little off. It should have read somewhere near 38K Ohms. Was the bulb sitting in water that was room temp? I dont test the sensors in free air so I'm not sure if that could affect it.

no i tested it in the air, should i put it in water

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