Hey everybody!
Im very new at this forum and also quite new to work on a Ford Ranger.
I have a Ford Ranger XLT 4x4 from 1998. And after seeing some pics I'm sure that I have the 4.0l OVH engine in it. Now here is My problem... the car just died on tve highway some days ago and dont start. It cranks but thats all. The local mechanic said it's probably the cam chain that snapt or jumped... but I get the P0340 OBD code and it's the cam position sensor as you al probably know😜? Well I found one for free at the junkyard from a 97 explorer and hooked it on but nothing. (Don't know if that's also broken). But the code tells me that it could be the whole circuit so I probably have to measure the whole wiring, contacts etc ? It gets fuel and have a spark, it cranks and I can feel it working the pistons so I'm not thinking it could be the chain that is the problem... do some of you have a good trick to se if the circuit is broken or grounded? What I can see is that the cabels are okey but I'm not a mechanic so... of course I wil try to measure the sensor to...

 

Welcome to the forum.

Do the 50/50 test
Pull off the large air tube on the front of the intake, you can leave it off for test
Open throttle and spray gasoline or Starting Fluid(ether) into the intake
Try to start engine

If it starts and dies you have good Spark but no fuel
If it doesn't start then you have no Spark, or Spark is at the wrong time
50/50

4.0l OHV is what you have, 4.0l SOHC(2001 and up Rangers) is a different engine and the one that did have timing chain problems.


Engine that dies while running usually means fuel pump died
Cam Position Sensor(CPS) is a secondary sensor so usually won't cause any engine problem except reduces MPG and maybe rough running at some RPMs, but software can change, and the CPS sits on the Cam Synchro housing, this housing's shaft is turned by the cam and it's shaft also turns the Oil Pump!
So no CPS signal could mean no oil pump, and Ford may have changed the computer software to stall the engine when there is no CPS signal.

I have heard of that on the Ranger 3.0l engines, but not on the 4.0l

Here is a how-to for changing CPS and cam synchro: Ford Ranger 4.0L Camshaft Sensor (CMP)

Hard to get to at the back top of the engine.
If you take off the sensor, then have someone crank engine you should see the shaft turning, that means timing chain is OK.
4.0l OHV Timing chain last the life of the engine, 400k + miles, so never has been an issue with these.

It is good to replace cam synchro when replacing sensor these did wear out

 

Thanks RonD!

Really good things to try ������!
Well it didn't start with start gas or fuel so no spark or "wrong" spark then.
So I Tried to remove the intake to get to the cam sensor but couldn't figure out how to remove the EGR tube that sticks to the plastic intake. It's really rusty nuts on it so I thought I maybe could just pop it out from the intake some how but it's stuck ��. I must say it's a really stupid place to mount the cam sensor but I won't give up. I'm so glad to hear that the chain last for the engines life time haha... Many thanks fore your answer so far RonD... it's late in Sweden now so I will continue tomorow������

 

No spark.

In the engine fuse box check PCM 30amp fuse, also called EEC Fuse
Also in the engine fuse box is the PCM(EEC) Relay
That relay should "Click" when you turn on the key.
The PCM Relay closes to send power(from PCM fuse) to the Coil(spark), fuel injectors and the PCM(computer).
If Check engine light(CEL) comes on when you turn on the key then PCM Fuse and Relay are OK

The Coil Pack has 3 separate coils inside, all 3 failing would be a very very long shot.
But check that the coils Red wire has 12volts with Key ON.

 

Thanks again for your time Ron! I turned the key and the check engine light came on so no broken fuses or relay. I think I have to get in the fight with the upper intake again and figure out a way to get the EGR tube to come lose to finally get to the cam sensor below... to be continued:-)

 

Do anyone now if I need to sync the cam in top dead center if I just took the sensor of to replace it. I mean the little black plastic thing with the magnet inside. Or I can just put the new sensor back? Thanx!

 

You can just put the sensor back on.

If you remove the whole unit, cam synchro with sensor, then you do need to time it with crank

 

Thanks Ron! That was good news! Well the old cam sensor was not broken, no corossion and the magnet worked ok. I will try a used one that I found for nothing att the junkyard first then I will try to measure the wires but do you know which goes to what?
Many thanx for all the good advice

Mattias Sweden

 

1998 4.0l will have 3 wire CPS, a Hall effect sensor
Black/white stripe is the ground

Light Blue/orange stripe is the 12volt power for sensor, comes from fuse 13(15amp) in engine fuse box, it powers several sensors and controls

Dark Blue/orange stripe runs to computer, pin 85

Just as a heads up, in 1999 engines were switched to 2-wire Variable Reluctance(VR) CPS, these are not interchangeable, 1998, and earlier computer, can't understand signal from VR sensor, and 1999, and up, computer won't understand Hall effect signal

 

Wow! Thanks

 

So Ron do you know if the sensor have a specific resistent when you measure it? if it's possible to measure that is?

Thanx!
Mattias

 

No, resistance test won't work with hall effect or VR sensors

Google: how to test a hall effect sensor with a multimeter

These sensors generate oscillating waves when a magnet passes by, so can't be tested "for sure" without oscilloscope or similar device
BUT you can test that it is outputting a signal using multi-meter set to AC Volts.
You will have to crank the engine over while meter is hook up as no AC voltage(oscillation) is generated unless the magnetic "wheel" is turning

 

Wow Ron! Your information is priceless... I'm so thankful!

 

Hey Ron! When me and a friend tested the contacts I also remembered your tip to look down where the sensor is supposed to be attached and se if the synchronizer spins when engine cranks... it did not move at al... so can it be the synchronizer that is broken? Or the chain?

Thanx for any help!
Mattias

 

Cam Synchro is same setup as a distributor had, they run off the cam gear drive, and same gear and shaft setup also runs the oil pump!!!

So if engine is running you would have massive valve train noise and then bearing trouble.

As no movement at the "rotor" could also mean no oil pump.

Timing chain on the 4.0l OHV was bullet proof, can't recall even one issue regarding timing chain on these engines.
But yes, if timing chain broke then cam and synchro would not turn and engine would not run.

I guess the only thing you can do is to pull the Synchro and check why rotor isn't moving.

You will need to re-time the synchro when reinstalling

Google: 4.0l ohv cam synchronizer images

Lower part has the HEX drive for oil pump shaft, then in the middle the gear that meshes with cam gear to drive the synchro shaft
At the top will be the "rotor" with a vane that spins with engine rotation, CPS reads that vane as it passes by the sensor.

Image here of synchro with shaft removed: http://www.explorerforum.com/photopo...edium/CPS2.jpg

Rotor "vane" is part of the shaft so if it isn't turning then oil pump isn't either
And you can see the "roll pin" used to secure synchro gear to shaft.
These roll pins could shear off on distributors, never heard of that with synchros, but if that did happen then no rotor movement and no oil pump either

 

Great! I knew you had a great answer :)! I will digg even deeper and se what's wrong. And desk with the retiming later... sounds difficult but not that hard. Many thanx and merry Christmas

Mattias

 

When re-installing synchro it may not go down all the way, that is because the oil pump's shaft hex is not lined up with synchro hex.
Just manually rotate crank 1/4 to 1/2 turn one way or the other and synchro will drop into place when hex lines up, then rotate it back to where it was, I assume TDC on #1 compression stroke :)
Then do the timing

 

W

 

When i look at youtube I can se that people are just marking up the old one with a marker and transfer the mark to the new one and rotate it until it's in the same please like the old one. Thats seans to be the only thing they do. Also using the special tool that often is included. So do I have to check timing after this?

Well I think I need to get the intake of anyway to reach the synchronizer and that is Creasy hard. The sensor was hard to reach and even see so the intake has to go I think.

 

Well that would work IF your rotor was turning, but since it isn't then it is not "timed" now, so duplicating it wouldn't work.

You may need to pull the upper intake to get better access, not sure, but the synchro should have enough clearance to come up and out with lower intake in place.


The synchro housing is attached to the sensor, the vane is attach to the shaft
So to time it you have to install the rotor vane to be at a specific spot when engine is at TDC #1 compression stroke, you do this by dropping in the synchro to mesh with cam gear, because gears are angled vane will move a bit, so you may need to pull it up again rotate it a bit, so it meshes with next tooth over, and drop it down again(and at this time you may need to rotate crank as said above to get synchro to drop down all the way.)
Once vane is in the right spot you can rotate(fine tune) the housing one way or the other to get an exact timing match, then tighten up the housings retaining bolt.

Same process as timing a distributor to fire at #1 TDC
You drop in distributor so rotor is pointed at #1 spark plug wire, then fine tune distributor housing(the cap) for exact BTDC firing with timing light.

The computer can fine tune CPS a bit by modifying its pulse, so while you need to get it as close as possible, exact is done by the computer

 

Ha! I manage to get the little **** out without taking the upper manifold of :)! It is dirty, old and it is not so tight and have a lot of play side ways but rotates by hand. So nothing seems to be broken.. I took some pics but don't know how to attache them with my iPhone.

 

So if the syncro is in one pice and everything is in place even if it's a lot of play up and down ( some mm ) and sideways and rotates when I turn it by hand it would turn? if the chain isn't broken of course. When I pulled the synchro up I could feel how it rotated on the way up so it was connected to the camshaft. So I'm wondering now if the synchro can stop rotating even if the camchain is okey. That wouldn't work in my book but I'm not a mechanic so :)

 

The the oil pump/CPS drive gear on the cam shaft is part of the cam shaft so can't be loose.

What about the drive gear on the synchro is it tight, roll pin intact?

 

Yes the roll pin is intact but there is a lot of play in it but not broken... I'm starting to wonder if I really saw the synchro not rotate... im unsure now so I will pop it in again and se if it's really don't move. On my synchro the pin that should rotate and get the Puls to the sensor is not that smal as the syncros I googled. It's 50% of the thing moving. Like a half moon but looks okay and not broken... I don't know but maybe it's harder to se if it's rotating or not when it's half of the rotating shaft?

 

Yes there were large vane and small vane

Image here: http://ww2.justanswer.com/uploads/jb...m_sensor_2.png

Large vane was for 3 wire Hall Effect Sensors