03 Explorer Sport, Engine cranks but won't fire

The engine in my 2003 Ford Explorer Sport V6, 4.0L w/auto trans will not start when cranking it over. It did not stall or run rough when it last ran. In the past the engine would seem to do this once in a while but give it a half hour or so and it would start back up.

Monday before this starting issue, the transmission would not shift up in gear when in drive. I was able to move the shifter to 2nd and the transmission would then engage this gear till you get to the next stop light or slowed down a lot. Once we started to look at the transmission problem the engine just stopped starting up all together. Not even the half hour wait will help it.

Now, It will rotate as long as the key is in start but the engine is just not firing. It does not buck as if it is missing a cylinder or two. There is no smell of raw fuel from the exhaust or any smoke being visible either from the exhaust.

What I have noted so far is that from reading the numerous entries on the internet pertaining to the condition, the likely candidates are crank or cam positioning sensors, the fuel pump, the ignition coil, PATs or the PCM.

We have done the following to try and narrow down to root cause;
• The Theft light will illuminate for ~3 seconds when the key is moved from off to run. It then turns off.
- Reports from the internet state that if the light turns off after 3 seconds all is good with the key.

• The Digital transmission range sensor will not let the engine crank over when the shift lever is in drive or reverse, seems to be working correctly in Park and neutral (starter is disabled).

• The fuel pressure at the valve at the end of the fuel rail is reaching a steady 65 psi when the key is moved from off to run, and still while cranking is 65 PSI.
- This pressure does not drop more than 1-2 psi when the key is off for a few minutes.

• All the spark plugs are receiving a high enough voltage to cause a spark and strobe an inductive timing light.

• The Fuel injector connections were tested with a NOID light. None of the injectors caused the NOID light to illuminate?
- The red line to the injectors is receiving a +12 vdc.
- The fuel injector control line does not seem to be grounding the injectors to supply the gas to the cylinders?

• The crank positioning sensor(CPS) was replaced as a precaution.

• Last night we checked all the wires from the connectors back to the PCM connector with a multi-meter for the following lines;
- Crankshaft and Camshaft Positioning sensors
- PCM engine temperature thermistor.
- Fuel injectors
- Ignition coil.
- Mass Air Flow Sensor (six wire).

At this point, is there any other causes for the fuel injectors to not work as a group?
• Maybe another sensor not listed above that could cause the Power train Control Module (PCM) to operate the fuel injectors?
• Or the has the PCM’s fuel injector circuit just died probably?

Any help would be appreciated.
Thanks
Ken

injectors not pulsing

There is a separate circuit for each injector to the PCM. I doubt that all of the PCM circuits would fail at the same time. The PCM computes the timing of the injector pulses based on the signal from the crankshaft position sensor. However, the PCM requires the camshaft position sensor signal to determine if a cylinder is on the compression or exhaust stroke. I suggest checking the connection to the camshaft position sensor.

On my 2000 Sport if an ignition key is used that is not recognized by the PCM the injectors are disabled. However, THEFT flashes rapidly when the starter is cranked or the ignition is on.

Thanks 2000StreetRod
I will try to meter a signal change on this line to verify correct operation in the engine. Originally I had metered this with a Digital Multi Meter outside of the engine and found that bringing a iron surface near the sensor base would change the meter reading.

Quick way to test the fuel pump, check the inertia switch below the passenger dash, you may have tripped it somehow, if that's ok, disconnect the line at the fuel filter and try to crank the engine. if fuel squirts out The pump is fine. If it doesn't... check the fuel pump relay and fuse. If those are fine then you have a bad fuel pump. If not change them and try again.

An easy temp fix for a bad fuel pump is to get a 4m length of fuel line. connect it to the fuel filter and run it to any old fuel pump, throw it in a jerry can of fuel in the trunk and wire it to any 12v ignition controlled circuit.

Some what a redneck fix but it'll get you going.

edit: just noticed you already tested fuel lol. never mind

Just to be sure, I tested the crankshaft and camshaft sensors last night. The crankshaft sensor is responsible for the initiation of the ignition coil firing. This was proven out via a timing light connected around a plug wire. When the sensor was plugged in the timing light would strobe when the engine was cranked over. Remove the plug and no more timing light strobe.

This camshaft position sensor (2 wire) makes no noticeable change to the timing light strobe when connected or not (just a what would it do type check on my part). There was a you tube video on testing this camshaft position sensor that said if you connect to it with a oscilloscope it should develop around 1.5 to 2 volts Pk-Pk. I did this experiment and noted that at best when connected to the wire harness it was only reaching 1.5 V Pk-Pk. So it is still in the possibilities as being degraded.

I have been inside the PCM and noted the board and chip sets are from Motorola. I traced the fuel injector lines from the 104 pin connector to the IC pins located towards the back of the board on the edge. No overt signs of a damaged part or over heated trace was noted along the path. The solder connections appear acceptable.

This cam positioning sensor being a $40 plus part makes me wonder; to replace it or just go after a PCM and the key programming costs.

Is there anything else that could disable the fuel injectors and not be part of the PAT system?

waste spark ignition

All_Season_Fun said:

Just to be sure, I tested the crankshaft and camshaft sensors last night. The crankshaft sensor is responsible for the initiation of the ignition coil firing. This was proven out via a timing light connected around a plug wire. When the sensor was plugged in the timing light would strobe when the engine was cranked over. Remove the plug and no more timing light strobe.

Click to expand...

The fuel pump runs for a couple seconds when the ignition is switched from off to on and any time the PCM determines the crankshaft is rotating as reported by the output of the crankshaft position sensor. The above test confirms the functionality of the crankshaft position sensor/PCM circuitry.

All_Season_Fun said:

This camshaft position sensor (2 wire) makes no noticeable change to the timing light strobe when connected or not (just a what would it do type check on my part). There was a you tube video on testing this camshaft position sensor that said if you connect to it with a oscilloscope it should develop around 1.5 to 2 volts Pk-Pk. I did this experiment and noted that at best when connected to the wire harness it was only reaching 1.5 V Pk-Pk. So it is still in the possibilities as being degraded.

Click to expand...

The camshaft position sensor has no effect on the ignition timing. Your vehicle has a waste spark ignition system. The spark plugs are paired. When one plug in the pair fires on the compression stroke the other plug in the pair fires on the exhaust stroke.

The camshaft position sensor allows the PCM to determine which cylinder is on the compression stroke. The PCM then uses the crankshaft position sensor to time to start of the injector pulse.

All_Season_Fun said:

I have been inside the PCM and noted the board and chip sets are from Motorola. I traced the fuel injector lines from the 104 pin connector to the IC pins located towards the back of the board on the edge. No overt signs of a damaged part or over heated trace was noted along the path. The solder connections appear acceptable.

Click to expand...

In my opinion the PCM is pretty reliable and rarely fails under normal circumstances. Caution needs to be observed when using an electric welder. The PCM has a few grounds that are common to other functions so I doubt a bad ground is the problem. Sometimes the PCM connector pins get pushed back into the connector and don't make electrical contact. But that is unlikely for all six pins. According to the wiring diagram there is a splice (S104) for the supply to all six injectors. Did you check for power at the individual injector connectors?

All_Season_Fun said:

This cam positioning sensor being a $40 plus part makes me wonder; to replace it or just go after a PCM and the key programming costs.

Click to expand...

At this point I would not replace the camshaft position sensor or the PCM.

All_Season_Fun said:

Is there anything else that could disable the fuel injectors and not be part of the PAT system?

Click to expand...

Do you have any way to read pending diagnostic trouble codes?
Have you tried your second PATS key?
Do you have remote start capability?

I have verified that the injectors had 12 volts to the supply side of the individual injector connectors.

Borrowed a code reader; there are no trouble codes being detected at key on.

The second PATS Key has been tried. ti performs as the main key with the theft light on for 3 seconds and then turn off the light.

There is no remote start that I'm aware of. We are not the original owners, so I will have to check this possibility out. Have not installed a remote starter so I'll have to learn the connection points quickly.

Thank you 2000StreetRod for reviewing this.

Theft light

My 2000 User Guide states:

When the ignition is Off the theft indicator will flash briefly every two seconds.

Is that happening?

When the ignition is On or in Start the theft indicator will light for three seconds and then go out. You posted that in Start it does that. Does it also do that in On?

Unfortunately, I'm mainly familiar with my 2000 Sport and I've read that your 2003 Sport is more like a Sport Trac than my Sport. Many members with after market remote start capability have posted about weird starting issues. I don't have one and am glad I don't. Remote start has to have some way to defeat PATS so it usually involves a hidden PATS key or a chip similar to the one on a PATS key that transmits a code recognized by the PCM. There's usually a box containing the key or chip hidden near the steering column in the proximity of the PATS receiver. The box (or another one) would have to include a receiver for the remote start fob transmitter.

I'm rapidly running out of ideas. If its not a remote start problem, about the only things left that I can think of is PATS or the PCM. The PCM has two types of writeable "non-volatile" memory. There's the keep alive memory (KAM) which draws power from the battery even when the ignition is off. And there is electronically programmable memory that does not require power. The key codes are stored in the latter type. I'm sure of this because my PCM at one time sat for many months with the battery disconnected and when power was restored the PCM still recognized my PATS keys.

Since you have no PATS fault indications I'm beginning to suspect that there is a PCM problem. The PCM has a collection of "generic" inputs and outputs that are assigned to functions according to the strategy loaded. It may be that the device that controls the injectors has failed or that the strategy has been corrupted. A combination of testing and reprogramming (usually performed by the dealer) may be required to detect the problem. A replacement PCM may be required to correct the problem. A replacement PCM will also have to be programmed to recognize the existing PATS keys. I suggest calling potential dealers to get an estimate before towing the vehicle to a dealer. A PATS qualified locksmith could program a replacement PCM for the two PATS keys but would not be able to test the PCM or reprogram the appropriate strategy.

Yes, The theft light will flash once every few seconds when in off or the key removed.
Yes, the theft light will go off in 'On' after 3 seconds.

You have a very good point about the after market starter problems. I will conduct a search around the steering column tomorrow for any mods having been done. A bit more research on the remote starter wiring will be done also.

The possibility of a PCM replacement is a decent chunk of change the wife and I have discussed. I have requests for pricing in for a Automotive Locksmith to program the keys to a new PCM that has been pre-flashed with the VIN information.

When all is back to working I will post the root cause that was found for the starting issue.

thanks again!