2001 Ford Mustang Faulty fuel injector symptoms not resolve

Hello,

Ok, since it is a 2001, just about any problem will turn on the engine light. So, is engine light on? if so to narrow the field will need to pull codes.

A couple possibilities are...

Ignition Control Module - Failing once warms up

Coolant Temp Sensor - Failing once warms up

Coil or Coils - Depending on if it has Coil Overs or a Coil Pack.


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The odd thing is, the check engine light is not on which makes it hard to diagnose since I cannot pull the error code.

How far is the nearest parts store or do you have a good scanner.

Since it is what could be concidered an intermittant problem, some scanner won't read them. However, your local parts store should be able too.

Another possibility is the Idle Air Control Valve.

I will take it in as soon as I can. How can I check if its the Idle Air Control Valve?

The Idle Speed Control (ISC) valve, also called an Idle Air Control (IAC) valve, is used on both throttle body and multipoint fuel injected engines to regulate idle speed.

To Test

turn the engine off, unplug the ISC bypass air solenoid connector, then restart the engine to see if the idle rpm drops (it should if the ISC solenoid is working). No change would indicate a problem in the motor or wiring.

The ISC solenoid can be checked by measuring its resistance. With the positive lead of a digital volt/ohm meter on the VPWR pin and the negative lead on the ISC pin, measure the resistance of the solenoid. On many applications, the spec calls for 7.0 to 13.0 ohms. If it is out of specs, the ISC solenoid is bad. Also check for shorts between both ISC solenoid terminals and the case.

If the ISC checks out okay, check for battery voltage between the ISC connector terminals while the key is on. Voltage should also vary when the engine is running. No voltage indicates a wiring or computer problem.

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I unplugged the ISC and started up the car, it died in a matter of seconds. I suppose that is a good sign. I tested the resistance and it was between 7 and 13 ohms. I tested the voltage between the connector and the battery with key in and turned to ON, and the only anomaly I noticed was that I did not get a reading on the right slot. I did get a reading from the left slot.

Ok, appears the IAC is good. I will ask the other techs to post test proceedure for the other components and the thoughts on your problem. I don't have access to my to get the proceedures. I am out of state for a few day. In mean time if you can test the TPS (Throttle Position Sensor).

You can measure the sensor's output voltage by packprobing the sensor conenctor with a voltmeter. First, check for the presence of voltage at the TPS with the key on. The TPS cannot deliver the proper signal if it does not receive reference voltage from the computer. Refer to a wiring diagram for the reference connection and look for 5 volts. The second check is the base voltage reading. Compare the voltage reading to the manual specifications. TPS voltage values are often specified to the nearest hundredth of a volt, so if the base TPS voltage reading is not within .05 volts of the specified value, adjustment may be needed (if it is adjustable). If it is not adjustable and the reading is out of specifications, replace the sensor. The third check is for the proper voltage change as the throttle opens and closes. Voltage should rise smoothly from about 1 volt to a maximum of 5 volts at wide open throttle. No voltage rise or skips in the reading means the sensor needs to be replaced.

In the first pin for computer reference voltage to TPS, I got a constant reading of 5.10v

In the second pin for TPS output to the computer, I got a constant reading of 0.04

For the third pin for voltage drop I got a constant reading of 0.6v.

All these readings were taken with the key in and turned to ON.

Did you actuate the Thottle while test each pin? If not do so and post results. Engine Coolant Temperature Sensor Test Engine Coolant Temperature (ECT) sensor uses a 5-volt reference voltage during engine operation. To check ECT signal voltage, backprobe between signal terminal and ground with engine running. To check sensor resistance, disconnect sensor connector and measure resistance between sensor terminals. For ECT sensor specifications, see ENGINE COOLANT & INTAKE AIR TEMPERATURE SENSOR SPECIFICATIONS table. For additional testing information, see TEST DA under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V - CNG & GASOLINE article.

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The check engine light came on today after a week of having problems so I took it in to the nearest auto-store the code they retrieved was:

PO303 CYLINDER 3 MISFIRE DETECTED.

I have not yet done the above mentioned tests but I will do them tomorrow if it is still necessary.

Sorry for delay getting back with you. I was out of state with wife who had hip surgery and we came home yesterday.

Anyway, now that there is a code before you do any part purchasing lets do a test...

First do your car have a coil for each cylinder? If so take the #3 cylinder coil and swap it with another one. To see if the misfire moves. If misfire moves then replace coil. I misfire does not move need to do some more tests.

Post finding....

No problem at all, I really appreciate all of your help. I was looking around under my hood and I have coil on plugs and I took out the 3rd coil and noticed that the boot was ripped at the end. I looked around on forums and noticed that other people had misfires, noticed their boot was ripped and replaced the coil. I did run continuity tests on that coil and the primary and secondary resistance match up. Here's a picture of the ripped boot.