1999 FORD EXPLORER 4.0 NO SPARK

[410Fortune]

Do you know anyone around you with a similar truck you can borrow their pcm/ key/ pats module for testing? This only takes a few minutes


I know you said you have no power at the coil pack, how are you testing this?
Have you checked for spark at the plugs?

 

[JOHN07]

Do you know anyone around you with a similar truck you can borrow their pcm/ key/ pats module for testing? This only takes a few minutes


I know you said you have no power at the coil pack, how are you testing this?
Have you checked for spark at the plugs?

unfortunately I don't know anyone around with the same vehicle, I thought about that.. as far as the now power to the coil, at first I pulled a plug wire off to see if I was getting spark, and had nothing, so I pulled the plug off that powers it, and the red wire that is suppose to have power with the key on which is the one closest to the fire wall if you are looking at it had no power nothing..

 

[410Fortune]

Do you have power at the red wire anywhere else? Injector? MAS?
(with key in ON pos)

 

[koda2000]

Do you have power at the red wire anywhere else? Injector? MAS?
(with key in ON pos)

Question - When you say MAS I assume you are referring to the MAF sensor. From reading your posts it appears you know quite a bit about vehicles. Why do you refer to the MAF as a MAS? I've never heard it referred to as a MAS. Just curious.

 

[410Fortune]

Mass Airflow Sensor
MAF = Mass Air Flow

To me "Airflow" is one word, so why would you split the word in half?
HAHAHAHA!!!
It's likely from the earlier trucks like in 89 when the 2.9L got a MAS that was the first time I encountered them it was called a MAS in the circles I run in..........and it stuck
Just like Ford calls it a DTRS, Chevy a Neutral Safety Sensor
I work on all sorts of stuff like Elevator systems (design them daily job), ATV, UTV, Sleds, Diesels, Toyotas, small engines, etc etc.....so my terminology may be a little different / off.
I deal in alot of metric stuff and international jobs so that does not help!
I have been driving/modding/building Ranger based vehicles since Kunz Korner at the old Fordranger.com way before TRS, etc......been here at EF for many years as well (including a 10 year hiatus)

"From reading your posts it appears you know quite a bit about vehicles"

Thank you! I am here just trying to learn and give back from the help I have received....it is so nice to be in the information age

 

[tripog]

ill be parting out a 2000 4.0 ohv explorer pretty soon if you end up needing a pcm, its loaded with the latest ford software according to fjds.
fwiw other than the dying at the stop light part, it sounds pretty similar to what my explorer does when i accidentally try to start the truck with the non pats key. if you had another ford vehicle do the same thing im almost wondering if its something you did maybe unknowingly to the vehicles.

 

[JOHN07]

ok, so im just about to give up on this vehicle. I know once I figure out the problem its going to be simple, but I ended up replacing the pcm, keys and what not, and it still does the exact same thing as it did before, any other ideas?

 

[tripog]

with the key on there is no power to the red wire that plugs into the coil pack. at first I pulled a plug wire off and checked for spark, once I determined there was no spark I back tracked to the pigtail, and nothing is there.

was this wire red and light green or just red?
fwiw i would go back to the original pcm and keys for testing, if you were able to pull codes from the pcm its most likely not bad. Here is some ford information on pats.

 

[EB4X]

What about the CAM position sensor?

 

[Mbrooks420]

Cam position sensor won’t stop spark.

 

[tripog]

What about the CAM position sensor?

Typically ohv engines can start with a bad camshaft position sensor it may just take a few tries.

 

[EB4X]

Cam position sensor won’t stop spark.

Not exactly true.....while rarer they can be the cause the ECM/PCM will not deliver spark.....

 

[410Fortune]

I agree
I have had a camshaft synchronizer and sensor cause a no start on a 98 OHV
Fought that truck for many many hours before it finally worked 100%, would run fine and then die and not re start. New synchro and cam sensor = worked for a while
So we replaced coil pack, crank sensor, fuel pump, pats key, halo, tried a loaner PCM, etc etc etc it was a bad cam sensor AGAIN
I was under the impression that a bad cam sensor would still start a OHV I was wrong on that 98, it was indeed the cam sensor causing the no start condition.
I too had no spark at coil pack and no power to coil pack that but I also had no power to any of the red wires
That is why I asked if you had power at the MAS or injector red wire?

ok, so im just about to give up on this vehicle. I know once I figure out the problem its going to be simple, but I ended up replacing the pcm, keys and what not, and it still does the exact same thing as it did before, any other ideas?

"PCM Keys and what not" = What exactly did you replace? Did you look at the halo on the ignition cylinder where the key goes? A broken or faulty PATS halo can cause all sorts of crazy crap with the pats system

It could be that your ignition halo is broken?

 

[JOHN07]

well I replaced the cam sensor, but not the synchronizer, and it is still doing the same thing, the old cam sensor didn't show signs of wear or anything on it. when I replaced the pcm I also replaced the keys, and the halo aswell.

 

[tripog]

well I replaced the cam sensor, but not the synchronizer, and it is still doing the same thing, the old cam sensor didn't show signs of wear or anything on it. when I replaced the pcm I also replaced the keys, and the halo aswell.

dont listen to people who just recommend replacing things without any actual diagnosis. there are a lot of them on this forum.

 

[JOHN07]

dont listen to people who just recommend replacing things without any actual diagnosis. there are a lot of them on this forum.

fortunately I had access to a donor vehicle so the pcm, keys and halo didn't cost anything, I got real lucky because it was the same year make and engine as well as the same serial number on the pcm

 

[EB4X]

I didn't recommend replacing anything, should it not need it, I posted link on how to test his cam sensor.

 

[Mbrooks420]

410fortune knows these vehicles as good as anyone else on the forum. I’m sure any advice he gives is pretty sound.

He also never said to just replace things.

This is one of the most knowledgeable automotive forums around, and surely the beat for Explorers and Mountaineers.

Since you’ve swapped the PATS gear, and PCM, I’m guessing you have a wiring issue that will need to be traced out. It seems everything has been replaced at the component level.

 

[JOHN07]

Everything that has been replaced has been of my own accord. everyone on here has been extremely helpful in their advice as to where to start and what to try. no one said I had to replace anything. this vehicle has been a pain in the butt since day one, and it may be why the people who owned it prior to me just left it with the title in it, but im to stubborn to let this vehicle get the best of me.. everything minus the pcm keys, and halo probably needed to be replaced any way. im not sure how the people prior to me took care of it. when I first got it I had to replace the head gaskets, so it is what it is on however long it take to figure out what the problem is, and maybe itll be the same problem as whats wrong with my 99 f150 because it did the same thing as my explorer. once I figure out the exact issue ill defiantly let yall know incase someone else is having the same issue.

 

[410Fortune]

Well said!!

Listen if it was easy you would not be here with this thread. Sometimes these trucks can throw a curve ball and what usually works to fix 98% of them will not fix the other 2%

it may be time for you to start testing the wiring harness? Lets get back to basics.
I re read this thread and took notes!! Koda is very wise and early on here he said:

"Spark is controlled by the crank position sensor. If you replaced the sensor and its pig tail and still are not getting spark the sensor signal sounds like it's not getting to the PCM or the PCM signal to fire the ignition coil is not getting to the coil. You will need to figure out which is the case. Could be an electrical connection issue, a wiring issue or perhaps the PCM itself (which IMO is the least likely)."


I'm very curious, when this happens (truck dies) have you checked fuel rail pressure?
Could it be a bad fuel pump again or power wire to it.... bad inertia switch/bad fuel tank connector? I have fixed more then one explorer by repairing the wiring connections at the fuel tank wire connector by the rear drivers tire. When I am hired to replace a fuel pump before I drop the tank I unplug the wiring and I power up the pump through the pigtail. More then once the pump has run. Then I test for power coming from the truck side of things. More then once I have found a bad inertia switch or fuel pump relay to be the problem. I have also had a simple power wire at the connector pin come loose, causing and intermittent no power to fuel pump issue. Saves me from dropping the tank and saves customers from buying fuel pumps they do not need.

I know you said you checked the inertia switch . When a truck dies on my and wont re start first thing I do is listen for fuel pump then check rail pressure
It seems we have skipped right over this in the thread and we are focused on only checking for power at the coil pack.

Basics:
1999 OHV 4.0
Dies at stop light won't restart
Replaced: fuel pump, crankshaft sensor & pigtail, cam sensor, all fuses, all relays, PCM/PATS components

Checked:
Wiring connectors at PCM and all sensors. Inertia switch no tripped, keep alive power at PCM.
CEL goes out while cranking, Theft light flashing like normal
No power at red wire at MAF (LOL) coil pack and others

So I still have two questions:
Have you checked fuel pressure when it wont re start?
Does it ever re start (after how long)?

Let me know if I missed anything