EECIV Closed loop temperature? 90 f150

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Jul 30, 2021 | 12:27 PM

broncobasher

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From: 13th Colony

EECIV Closed loop temperature? 90 f150

Does anyone know what the ambient temperature and or engine temperature has to be for the system to go to closed loop? Does the ECM base it on the ACT temperature or the ECT or a combination? Generally when I start my truck, it idles high for a few minutes then drops down to normal idle. Today, I start it, it drops down to normal idle almost immediately. Of course it is above 80 degrees ambient temp. Is it normal to do this? Or should it always idle high when first starting?

90 F150 302 4X4

Thanks,

Broncobasher

Jul 30, 2021 | 12:47 PM

sandymane

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From: Houston/Sugar Land

This is from rla in 2018.

I would measure the ACT/IAT sensor: Ford Fuel Injection » Air Charge Temperature (ACT)

And for giggles since I sometimes do not trust computers, verify the ECT value reported from the computer is correct: Ford Fuel Injection » Engine Coolant Temperature Sensor (ECT)

The computer is programmed to drop out of closed loop after a certain TPS signal is reached, do the same for the TPS (with a meter): Ford Fuel Injection » Throttle Position Sensor (TPS)

I would not suspect the TPS is the cause since you do not state the transmission shifting is affected. But it needs to be verified.

Jul 30, 2021 | 02:21 PM

broncobasher

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From: 13th Colony

My transmission is an AOD, not AODE. It isn't hooked to the computer, so not sure how the TPS would affect it.

Broncobasher

Jul 30, 2021 | 02:22 PM

broncobasher

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From: 13th Colony

Quote:

Originally Posted by sandymane

This is from rla in 2918.

I would measure the ACT/IAT sensor: Ford Fuel Injection » Air Charge Temperature (ACT)

And for giggles since I sometimes do not trust computers, verify the ECT value reported from the computer is correct: Ford Fuel Injection » Engine Coolant Temperature Sensor (ECT)

The computer is programmed to drop out of closed loop after a certain TPS signal is reached, do the same for the TPS (with a meter): Ford Fuel Injection » Throttle Position Sensor (TPS)

I would not suspect the TPS is the cause since you do not state the transmission shifting is affected. But it needs to be verified.

I already tested the ACT values and they matched current ambient temperature. I was just wondering what temps it is supposed to switch at.

Broncobasher

Jul 30, 2021 | 02:49 PM

EllieMae94

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From: Mid Missouri

It goes into closed loop at 160°F

Jul 30, 2021 | 03:06 PM

sandymane

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From: Houston/Sugar Land

Here is another copy of a thread for you to ponder
Open loop / Closed loop? - What causes bothYou're also in open-loop at wide open throttle (WOT)

Closed loop control in general refers to a control strategy in which the output is fed back into the processor to modify the input signal in order to maintain a desired output. In open loop control there is no feedback, the processor simply drives the output device to a predetermined value. In the case of your truck, the O2 sensors modify the signals generated by the throttle position sensor (TPS), engine coolant temp (ECT), manifold absolute pressure (MAP) sensor, etc to correct the timing and the amount of fuel the injectors provide. This is the normal operating mode "warm cruise" and it is the most efficient and has the lowest emissions. In the cold start mode, the engine runs intentionally rich as it does at WOT. Neither efficiency nor emissions are optimized in this mode.

And one more.

Ok, when the comp is running in open loop, the comp runs the engine off of tables. Tables being pre programed sequence of events that at throttle position "x", and mass air meter reading "y", air temp "z", at said rpm, the injectors pulse at that desired amount. Now I know this sounds complicated, but it isn't. Now when it runs in closed loop, the air fuel ratio is being read by the o2 sensor and sending a signal to the comp to richen or lean it per the o2 sensor. Now if you had an air/fuel ratio gauge installed, when in closed loop, the gauges fans violently because it is seeing the swings from rich to lean. hundreds of times a sec. But when the comp is in open loop, and the comp adjusting fuel ratio off the tables instead of the o2 sensor, it will give you a smooth steady reading of air/fuel ratio. I hope this makes sense.

Jul 30, 2021 | 09:38 PM

broncobasher

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From: 13th Colony

Quote:

Originally Posted by EllieMae94

It goes into closed loop at 160°F

that is what I wanted to know. Is it basing it on the ECT?
Thanks

I understand what close loop means and how feedback loops work. Studied that in system dynamics at GT.