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Jan 26, 2013 | 12:16 PM

Quigles4

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Code help needed

I got some codes pulled for my 91 f250 351w. I got a 21-24 under "o" condition. All it says is that some sensors are out of range. They are sensors that have been replaced before. I just don't know what out of range means. Any help?

Jan 27, 2013 | 05:26 AM

rla2005

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From: Kentucky

A much better definition of codes here: Fuel Injection Technical Library » 2 Digit Self-test Codes 11-32

DTC 21: ECT out of self test range 0.3 to 3.7 volts.

DTC 24: ACT sensor out of self test range 0.3 to 3.7 volts.

The most common cause of those codes is not warming up the engine before running the Key On Engine Off (KOEO) tests.

DTC 22: MAP sensor out of self test range.

DTC 23: Closed throttle TPS voltage higher or lower than expected.

Your poor engine performance is probably related Code 22 and 23. If you have replace the MAP sensor and TPS before then it is time to start checking wires and signal output.

For reference:

Fuel Injection Technical Library » Engine Coolant Temperature Sensor (ECT)

Fuel Injection Technical Library » Air Charge Temperature (ACT)

Fuel Injection Technical Library » Manifold Absolute Pressure Sensor (MAP)

Fuel Injection Technical Library » Throttle Position Sensor (TPS)

Jan 27, 2013 | 05:30 AM

rla2005

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Quote:

Originally Posted by Quigles4

You should also stick to one thread: https://www.ford-trucks.com/forums/1...nightmare.html

Jan 27, 2013 | 08:18 AM

Quigles4

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What should I look for in the wires. And how should I go about testing the output. I'm not very experienced with automotive wiring at all

Jan 27, 2013 | 09:49 AM

bashby

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From: Charles Town, W bygod Va

Clear the codes then check them again with the engine fully warmed up, no point in chasing a false code.

Jan 27, 2013 | 10:27 AM

Quigles4

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Well I let it warm up and just got 22 and 23. When the motor is under load it sputters and bucks. I'm wondering if the problem is the map sensor or relates to it

Jan 27, 2013 | 11:55 AM

bashby

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From: Charles Town, W bygod Va

Bad spark plug wires will cause a missfire under load. MAP sensor is probably the most important sensor and will cause sputtering. Are you seeing any black smoke from the tailpipe when it is sputtering?

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Jan 27, 2013 | 12:28 PM

rla2005

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From: Kentucky

Quote:

Originally Posted by Quigles4

What should I look for in the wires. And how should I go about testing the output. I'm not very experienced with automotive wiring at all

The links I posted before lists the expected values at different operating conditions. You will need a Voltmeter to test the TPS. Testing the MAP is a little more involved because the output is a frequency not a varying voltage. I have a Digital Voltmeter (DVM) that can measure voltage and frequency (as well as resistance).

As noted previously the MAP sensor is a key input to the PCM for controlling the engine and transmission, if it is an electronic controlled version such as an E4OD.

Jan 27, 2013 | 12:29 PM

#10

bashby

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From: Charles Town, W bygod Va

Quote:

Originally Posted by Quigles4

Yeah. It does that on idle

Probably a bad map. Sometimes they will run better with the map unplugged. The comp uses set values when it has no signal as opposed to it believing what the bad sensor is telling it.