1995 Explorer 4.0L OHV: "Engine Out" Timing Synchronizer/ CMP Sensor backprobe test

[Tom Graham]

ENGINE-OUT (removed from vehicle) PROCEDURES & STEPS FOR SYNCHRONIZER TIMING & CMP SENSOR BACK PROBE TEST ON 1995 4.0L OHV:

These are the steps (with improvised procedures) to precisely and correctly align your camshaft position sensor mounted on the synchronizer (with the sight glass) when the engine is out of the vehicle, on a 1995 Ford Explorer 4.0L OHV Pushrod V6 Engine with OBD1 DTC and EEC-IV PCM. First follow the steps to drop in your synchronizer then proceed with the following to perform the back probe test on the CMP (camshaft position) Sensor

1. First set the #1 Piston to TDC on Compression Stroke. The needle on the Crankshaft Pulley (Harmonic Balancer) points directly at 0 degree mark. Then loosen the synchronizer retaining bolt until the synchro body rotates easily.

2. Find the 26° mark ATDC (After Top Dead Center) on the Crankshaft Pulley. (No such mark was present on my pulley so I made a mark myself with a chisel & hammer with a light tap.
I first made the mark incorrectly then corrected after checking with tape measure. The mark should be 1 & 11/32" ATDC from the 0° mark (counterclockwise if facing the pulley.)
See image:

3. Using a torque wrench or breaker bar & 19mm Deep socket, turn the harmonic balancer clockwise two revolutions to take up any slack in the timing chain, stopping at the 0° mark.

4. Continue slowly turning the pulley clockwise until the pointer is on the 26° ATDC mark then stop.

5. Note where the voltage indicator marks are for the 3 pins on the rear of the camshaft position sensor mounted on top of the synchronizer. One on the right is positive"+" middle is "0" and the left pin is negative "-" See image.

5. Using an AC to 12V DC Power transformer or a 12V DC Battery, (I used a 2 Amp 12V power supply for a WiFi router) connect the 12V Positive wire of the lead to the "+" pin on the CMP Sensor. Then connect the negative lead to the "-" pin. Then plug it in the wall or extension cord. Here is an image of the 2 Amp 12V DC power transformer I used for this test:

Here is an image of the power supply leads connected to the CMP Pins using alligator clips: (Make sure you have the 12V positive wire clipped onto the + pin on the CMP.

6. Set your volt meter to DC Volts to perform this test. Connect the negative probe to the negative aligator clip as shown in the image below.

7. Place the red or positive lead of the volt meter on the center CMP Sensor pin marked "0". See image:

8. Being careful not to touch the leads together, slowly rotate the synchro body counter clockwise until voltage appears on the meter.
Then rotate the synchro body clockwise until voltage reads 0. (No volts)
Then very slowly rotate the synchro body counterclockwise until the exact point when volts begin to show on the meter screen (my reading was 11.49 volts).
Lock down the synchro retaining bolt and disconnect the wire leads. You are done!

This is an image of the synchro vane position in the sight glass after completing this step (with crank pulley still at 26° ATDC)

Here is the position of the Installed Synchro in relation to the center engine line after completing this test: (The Crank Pulley is still set to 26° ATDC)

I hope these instructions are helpful to someone. I had to figure this out on my own...

 

[smegun]

at 0 deg TDC my window looks like this at 26 deg ATDC it looks like yours so i went with it but i still have misses and no power yet after new head work and such on rebuild ... i want to guess its the sensor itself can i get just a sensor for the 94 and put it in this syncro

pretty old unit and the truck since purchase has had an acceleration problem and worsening i parked the truck when it developed a real bad miss ......did most of a tune up before taking the heads off to find a recessed valve and some thinning seats had the heads reworked thinking that was the missing problem but turns out nor ..... even with new lifters rockers and rods its pretty much the same miss even though the parts replaced were considerably scored and scratched out ... not having fun with a head gasket rebuild top end yet

 

[Tom Graham]

Have you got any engine codes on the OBD 1 PCM? I would check the fuel injectors for trash/varnish...clean them if necessary or replace. I would also check the gap on the spark plugs. I bought new Motor Craft OEM Plugs and the gap was way out on some by as much as 15 thousands. Proceed from there with a thorough check of each your Coil Packs.
Stupid question, but when you performed the Synchro CPS Backprobe test, are you certain that you had #1 Cylinder at TDC on the Compression Stroke?
If it was on the exhaust stroke when you stopped in your Synchro, then it is out by 180° and will need to be pulled and re-stabbed with #1 Cylinder at 26° Before Top Dead Center on the Compression Stroke.
If you aren't sure let me know and I will walk you through it.

 

[smegun]

no trouble light yet but the truck has only been run for short test runs ..... well i assembled with the window as above i just added the pic view at 0 degree mark on harmonic when i went to 26 degree ATDC the view in the window matches the above tutorial .... how does your window look at those two points the diagrams for the part are just ok like does it come apart to put in a new sensor ?? ... ive heard that i can be 180 out and i did rotate the harmonic before during a chain job but nothing changed in the vehicle performance so i parked it for awhile got the heads worked .... these with window ??? compression stroke vs . ???? other tutoriials for more common syncros describe the lobe needs to point twards firewall this window version main head is tucked in twards engine .... been trying to get that right ... did common tuneup wires plugs coil etc.... still ran poorly did tensioner job new injectors still ran poorly ...ive been everywhere man(johnny cash) now 400 in head work rods lifters rockers and gaskets still runs poorly im here again at the window

were is that lobe supposed to be on the cam syncro .... I mean thats what the window is for discontinued in most years more pcm control probly better

 

[smegun]

damm i was looking at that syncro with the heads off little depressed that i have to shimmy across the hood of my car to get access ... and the 10 mm wont budge at moment i might have to cut the wrench down or buy that ford part ...stupid 99 dollar fix evidently

 

[smegun]

someone keep telling me that I could be 180 out on the cam syncro but my window on the sensor looks right
...other tutorials say that the main vain has to be facing the fire wall (ford tuning cap) but here these type use a volt meter to set timing(what is under those screws can sensor be replaced ?) ….dosent seem logical with a window on the sensor .....ls the compression stroke identical to the exaust stroke on the window ? …. im having doubts about cranking the motor till I know what the window is supposed to look like is the window the same during the exhaust and compression stroke ?? here the pic is of mine at 0 deg TDC running like crap missing

 

[smegun]

26 ATDC red mark is further clockwise

 

[jessebretado93]

someone keep telling me that I could be 180 out on the cam syncro but my window on the sensor looks right
...other tutorials say that the main vain has to be facing the fire wall (ford tuning cap) but here these type use a volt meter to set timing(what is under those screws can sensor be replaced ?) ….dosent seem logical with a window on the sensor .....ls the compression stroke identical to the exaust stroke on the window ? …. im having doubts about cranking the motor till I know what the window is supposed to look like is the window the same during the exhaust and compression stroke ?? here the pic is of mine at 0 deg TDC running like crap missing

View attachment 168738

I know this post is old but I'm pretty sure people still look this up.... I have a 95 Ford 4.0 ohv.I got rid of the old style sensor and I put a new one in from a 97 works perfectly fine don't have to worry about that window...

 

[EB4X]

I know this post is old but I'm pretty sure people still look this up.... I have a 95 Ford 4.0 ohv.I got rid of the old style sensor and I put a new one in from a 97 works perfectly fine don't have to worry about that wind

Interesting, I've read that this "might" work but I didn't want to risk it and went with putting matching/ old style in... fun job ! !
But you had to go to junkyard to get the newer style matching plug/ connector and wire it in "with all that space and slack on wiring waayyyy back there." ....
As you observed, and I guess main motivation for going that route is the newer style ones are about 1/3" or less the cost than matching / old style ones and are in abundance on Ebay etc... I haggled a little with seller and they accepted $90 for mine whereas the newer style ones were going for about $30 and up.

 

[GreenX94]

I know this post is old but I'm pretty sure people still look this up.... I have a 95 Ford 4.0 ohv.I got rid of the old style sensor and I put a new one in from a 97 works perfectly fine don't have to worry about that window...

Digging up the past here also. I just swapped in a new style 3 wire into my 94. No drivability issues before the swap, just a 214 code and a cel, but otherwise she ran just fine. After the swap and following the install for a 94 sensor with a new part I’m having misfires on accel. Did you do something different when you put the new sensor in? I verified #1 tdc on compression stroke, set the sensor at 26 ATDC per the manual, and had a voltage reading at 26 ATDC. I’m just feeling lost at this point and am trying to avoid making adjustments while it runs, but if that’s the tocket so be it.

For what it’s worth though, she idles mostly fine.

 

[EB4X]

If "jessebretado93" does not reply here I have the correct one for your vehicle (same as my 95) NEW and FREE ...
the plug elbow just got a minor crack in it but totally intact, I slapped some epoxy on crack and it's rock solid. Seller sent me free replacement which is in rig now.
Just reimburse me shipping ... probably around $14. These are going from $99 to $147 on Ebay.
**ALSO, 410Fortune has performed the newer part installation on our older models, maybe you can msg him or he'll chime in soon.

 

[410Fortune]

when installing the 96-97 style sensor into the earlier engines USE THE SYNCHONIZER TOOL to align the cam sensor to the synchronizer body
Bring engine to TDC compression stroke, cyl 1, install alignment tool for your 96/97 sensor and drop the synchronizer in.....forget trying to set it at 26 degrees after top dead center, that was for the old sight glass type sensor..........

Make sure you get the wiring correct at the new connector as well

 

[GreenX94]

If "jessebretado93" does not reply here I have the correct one for your vehicle (same as my 95) NEW and FREE ...
the plug elbow just got a minor crack in it but totally intact, I slapped some epoxy on crack and it's rock solid. Seller sent me free replacement which is in rig now.
Just reimburse me shipping ... probably around $14. These are going from $99 to $147 on Ebay.
**ALSO, 410Fortune has performed the newer part installation on our older models, maybe you can msg him or he'll chime in soon.

If "jessebretado93" does not reply here I have the correct one for your vehicle (same as my 95) NEW and FREE ...
the plug elbow just got a minor crack in it but totally intact, I slapped some epoxy on crack and it's rock solid. Seller sent me free replacement which is in rig now.
Just reimburse me shipping ... probably around $14. These are going from $99 to $147 on Ebay.
**ALSO, 410Fortune has performed the newer part installation on our older models, maybe you can msg him or he'll chime in soon.

I’ll pm you, because if this issue doesn’t get sorted out then I’ll have to just stick the old style back in. Just sucks I’ll need to replace the connector for it since I had to snip off the old one for a new style plug

 

[GreenX94]

when installing the 96-97 style sensor into the earlier engines USE THE SYNCHONIZER TOOL to align the cam sensor to the synchronizer body
Bring engine to TDC compression stroke, cyl 1, install alignment tool for your 96/97 sensor and drop the synchronizer in.....forget trying to set it at 26 degrees after top dead center, that was for the old sight glass type sensor..........

Make sure you get the wiring correct at the new connector as well

So for what it’s worth I did install the new style with the alignment tool at0 TDC on cyl 1. Only reason I messed with it and went the book route was because I was having the same drivability problems. Not discounting the possibility though that I may have just got a bad sensor, but the cel doesn’t come on until I try to drive it and it begins to misfire. Otherwise idle is all good. I’ll try and reinstall it without messing around with the 26 degree stuff and see what happens. Thanks dude!

 

[410Fortune]

on compression stroke??
MAKE SURE

once it is dropped in and aligned to the cam there is no more messing with it
If you still get misfire code it maybe time to look elsewhere?
try again and then post up the codes if it does not work

 

[GreenX94]

on compression stroke??
MAKE SURE

once it is dropped in and aligned to the cam there is no more messing with it
If you still get misfire code it maybe time to look elsewhere?
try again and then post up the codes if it does not work

This is absolutely embarrassing but the sensor was perfectly fine.

I may have switched the #2 and 3 cyl wires when I put the coil back in. Swapped them into their correct spots and she is back to normal, no issues. Thanks for the insight on everything @410Fortune.

@EB4X turns out I won’t be needing a 95 sensor after all. Thanks for the offer though!

 

[EB4X]

Great news! Don't feel bad, we all slip up here and there.... haste makes waste.......