2007 Explorer 4.6L no spark

[PotatoExplorer]

The codes are still there. You just need to use better scanner.
I downloaded forscan onto my laptop, and see old codes even if the CEL is off and my scanner shows no codes.

When I was in similar situation, I just went to Ford at the end of my frustration, and said I would pay for up to 2 hrs of diagnostic time, no repair.
I knew my problem withing 45 minutes.
They may figure out your problem quicker then you think.

Explorer_PL, just out of curiosity, how much does an hour of Ford diagnostics time run you up there in NY?

Just a thought 1964 Comet, could you have bad gas?? (lol, bad gas)

 

[Bill MacLeod]

Do you have battery voltage to each cop with key on?

Power to the fuse comes from the PCM relay # 48.

 

[1964Comet]

There is no power to the coils. The PCM relay on this vehicle is #55A in the under-hood fuse panel, is that the one you are referring to?

 

[Bill MacLeod]

I'm looking at my 2006 manual and it shows relay #48 as the PCM relay and right in front of #43 fuse. #55 relay is for the starter and 2nd in from top right of Battery Fuse Box. Your 2007 may be different and that sure would surprise me.

Can you swap some other relay in for the PCM relay? Possibly the Front Wiper relay (#47 in my manual) or possibly the Blower relay (#56 in my manual).

It's worth a try. Also may sure your battery is fully charged.

 

[Bill MacLeod]

Jim:
I just downloaded a 2007 owners manual and the battery fuse box on page 244 is identical to my 2006 manual. Not sure why we are not identifying the same relays?

edit - page 229 of the 2007 manual

 

[1964Comet]

I appreciate your efforts in helping me solve this, it appears we are looking at different books.

My 2007 owners manual has the under-hood fuse panel info. on pages 286-288. The relays listed go from 46A to 49 & omit 47 & 48. The PCM relay is #55A & I tried swapping it with the front wiper relay (#55B) but unfortunately it did not resolve the problem.

The battery is fully charged, I had to re-charge it after too many attempts to start it with no luck.

Thanks! -Jim

 

[Bill MacLeod]

Well I'm stumped about this discrepancy. My 2006 manual shows 6 large relays. 47,48,49, 54,55 &56.
The 2007 manual that I downloaded tonight shows the same as above.
I'm perplexed............

But lets continue. I see a small 15 amp fuse #39 PCM power. Have you verified that this fuse is functional?

Not sure if you answered this earlier, but did the PCM communicate with your scan tool?

Are you sure that the new crank sensor is good? (try swapping the old one back)

What is your cranking voltage?

Crank rpm should be 150 to 350 rpm, but don't know if you can check that.

Going to do some testing on my truck tomorrow.

 

[Bill MacLeod]

Couple items to check.

1) Disconnect TPS harness and check voltage to middle 2 wires with key on, engine off. Advise results.

2) Disconnect Crank sensor harness and check voltage to each wire with key on, engine off. Advise results.

 

[Explorer_PL]

PotatoExplorer -

$ 135 an hour at Ford in Paramus NJ.

 

[1964Comet]

Bill, below are my responses (in red) to your questions:

1) Disconnect TPS harness and check voltage to middle 2 wires with key on, engine off. Advise results. 4.95V

2) Disconnect Crank sensor harness and check voltage to each wire with key on, engine off. Advise results. I could not get a reading, not sure if it is supposed to be zero or I wasn't getting a good contact, it is very difficult to reach this plug.

3) I see a small 15 amp fuse #39 PCM power. Have you verified that this fuse is functional? Yes, I have verified that it is functional

4) Not sure if you answered this earlier, but did the PCM communicate with your scan tool? Yes, my scan tool is communicating with the PCM. I've ordered a USB adapter cable so I can connect to my laptop & hopefully do a more in-depth scan.

5) Are you sure that the new crank sensor is good? (try swapping the old one back) It is my understanding that an issue with the crank sensor would also disrupt the signal to the injectors, is this correct? Since my injectors are working, I have ruled out the crank sensor. I really do not want to go through the trouble of swapping this sensor again unless it seems necessary.

6) What is your cranking voltage? 10.78V (battery voltage with the ignition to ON is 12.08V)

7) Crank rpm should be 150 to 350 rpm, but don't know if you can check that. ~250 rpm

 

[Explorer_PL]

I recall when I was swapping my v8, i broke a clip on the plug on the crank sensor. I believe it is same as the cam sensors, all 3 sensors are the same I believe. I also recall that to replace it you need to get the AC compressor out of the way ? It's a pain.

Anyway, the first time, after dropping a new "used" engine in, it would crank, but no start. Not sure if I had spark, but I went under and re-seated the plug, and it started.

 

[1964Comet]

Yes you do have to move the AC compressor to replace the crank sensor, & I agree it is a pain!

I did re-seat the plug & made sure it is fully connected.

I also thoroughly inspected the engine bay & wiring & did not see any signs of mice (droppings, nest, etc.) or any chewed or damaged wiring.

Is there a test I can do on the old crank sensor (since it is already out of the vehicle) to verify whether or not it is within spec?

 

[Explorer_PL]

As we agreed it's a pain to change that sensor. But if you were to swap it with one of the cam sensors, that would eliminate those unknown.

If you get a cam sensor DTC then, it would mean the sensor is faulty.....

 

[Bill MacLeod]

To test the crank sensor, use a pin/needle and insert it parallel to the a wire into the connector until it bottoms.(with key off)
Make sure the exposed part of the needle is not grounded to anything, then turn key on and measure voltage.
The crank sensor and cam sensor(s) are all 2 pin, but supply different feedback to PCM (reference voltage)

The PCM needs to know the position and speed of the crank (read from the saw tool wheel). The CKP is the primary source for ignition info to the PCM. (timing)
The CMP(s)identify when #1 piston is on its compression stroke so the PCM can synchro the correct firing of the fuel injectors. Cop's use the CMP signal to select the correct coil to fire.
If there is no crank signal then the coils will not receive info (voltage) from the PCM.

Since you have no voltage at the coils suspect (hope) an issue at or near the CKP.

TPS is good, crank RPM is good, battery voltage is somewhat low.

I'll check to see what info I can find regarding bench testing a crank sensor. (CKP)

 

[Bill MacLeod]

Resistance should be between 250 - 1K ohms.

 

[1964Comet]

I have not had a chance to re-check the voltage to the CKP yet, but the old CKP I replaced measured at 341 ohms so it looks like it is still good & not what was causing the problem. I will pull out the replacement CKP tomorrow & measure the resistance along with the voltage to the CKP plug & report my findings.

Since the CKP itself is most likely not the cause, what else should I check? Is it possible that my reading of zero at the CKP plug was accurate & there is no power to the CKP? What might cause this (excluding the fuses & relays that have already been checked)?

Thanks again for all of the help! -Jim

 

[Bill MacLeod]

Jim

The crankshaft position sensor (CKP) has a supply and return to the PCM. Pin 46 is GR-BN (green w/ brown stripe) and pin 47 is YE-VT (yellow w/ violet stripe). There is a ground shield in the 2 wire harness with a BK-YE wire. (black w/yellow stripe) This ground wire goes back to splice S109 which runs to connector C110. C110 runs back to a common ground G106 that also has 4 other black/yellow ground wires all from the PCM.

Not sure what this ground shield purpose is, but the PCM uses the CKP signal to calculate a spark target and then fires the coil pack(s) to that target. No CKP signal = no spark from Cops.

All of the above is from 2006 service manual and wiring diagrams.

Check for a pm.

 

[1964Comet]

Finally figured out the issue with the Explorer, a wire from the fuse box to the PCM was damaged. After running a bypass wire (instead of tearing into the harness), the Explorer now runs again! Thank you to everyone (especially Bill) for the help! -Jim