rover 75 cdt camshaft sensor voltage

beededea · 27th February 2017, 13:28

I just did a quick check on my rover 75 cdt camshaft sensor voltage after some warm start issues where it recently took 4-5 attempts to start, however it starts well on a cold morning (all renewable items recently serviced, pump is pushing well, car runs beautifully). The voltage on the yellow wire reads only 6.9v during cranking and when idle. Not much change when ignition on with engine not running.

I read on another post that it should be reading 9v from the yellow wire, is the low reading indicative of a possible camshaft sensor failure?

Ordered new one just in case.

FrenchMike · 27th February 2017, 17:36

Quote:

Originally Posted by beededea

I just did a quick check on my rover 75 cdt camshaft sensor voltage after some warm start issues where it recently took 4-5 attempts to start, however it starts well on a cold morning (all renewable items recently serviced, pump is pushing well, car runs beautifully). The voltage on the yellow wire reads only 6.9v during cranking and when idle. Not much change when ignition on with engine not running.

I read on another post that it should be reading 9v from the yellow wire, is the low reading indicative of a possible camshaft sensor failure?

Ordered new one just in case.

Hi,here the voltage you must get on an oscilloscope (at idle)

a DC meter will gives the medium value so around 9 /10 volt,(12v x duty rate)

Mike

beededea · 27th February 2017, 21:03

A continuous 6.9v then is faulty...?

FrenchMike · 28th February 2017, 08:17

Quote:

Originally Posted by beededea

A continuous 6.9v then is faulty...?

To confirm ;take a measurement, Engine stopped ,ignition ON , sensor removed .

move a piece of iron in front of the sensor and note the two values

beededea · 1st March 2017, 12:19

The new cam sensor arrived (OEM), we installed it, checked the voltage with an analogue multimeter and it was 12v consistently... car still hard to start.

Installed the old cam sensor that was reading 6.9v, now reading 12v too. Car still hard to start. Runs beautifully when it catches.

Confused. Possibly my old digital multimeter was giving the wrong reading when it said 6.9v, taken that to bits too...

Any ideas?

beededea · 1st March 2017, 13:17

Quote:

Originally Posted by FrenchMike

To confirm ;take a measurement, Engine stopped ,ignition ON , sensor removed .

move a piece of iron in front of the sensor and note the two values

Both operate as expected. Move the iron to the sensor, switch operates, needle drops to zero.

Dropping the cam sensor into the freezer to see if that helps.

FrenchMike · 1st March 2017, 14:44

Quote:

Originally Posted by beededea

Both operate as expected. Move the iron to the sensor, switch operates, needle drops to zero.

Dropping the cam sensor into the freezer to see if that helps.

Mind you ,a warm start issue can be caused by a leaky injector too

In doubt ,carry out a leakback test

beededea · 1st March 2017, 16:45

Have tried it in the freezer, no effect.

About to try another cam sensor from a car that starts well. That will give an indication of whether my old cam sensor/new OEM sensor are slightly out of spec.

After that I will try the various voltages from other sensors and then the leack back test. I looked into the plenum chamber through my grommetted inspection hole and noticed some damp in the bottom, certainly not swimming but dampish. I'm going to dry out the chamber and check the contacts at the ECU, then the leakback.

beededea · 26th July 2018, 16:14

Awakening this post from the dead using the powers invested in me!

The previous car that had this problems is dead and gone. Car 1.

However the problem has returned on another car. Rover 75 CDT, Car 2... It is a problem.

Battery is very good. Car 2 has had a recent service, fuel is good. Generally runs like a train. Plenty of power.

The engine is cool from a night's standing but in the warm weather we are experiencing now (summer 2018 34 degrees) the car turns over but will not easily start. After four or five attempts at 10 turns each the car eventually starts.

Car 2 then starts and runs with a little initial faltering that quickly disappears. Then runs like a train. Plenty of power.

But...when the engine is warm the problem is even worse. Restarting can take 20-30 cranks.

I took the cam sensor and placed it into another engine in another car -
Car 3. and it started first time so it seems good. To confirm I have tried three cam sensors (one new) in the Car 3 and it starts first time.

Makes no difference in car 2 which cam sensor I use.

Testing the value at the fuel pressure sensor on the end of the rail next.

Any thoughts?

Mike Noc · 26th July 2018, 19:12

An injector leak back test is easy enough to do, and will check if one or more injectors is leaking excessively.

27th February 2017, 13:28	#1
beededea Regular poster 75 connie tourer, MGZT-T Join Date: Mar 2009 Location: Aylsham Posts: 99 Thanks: 9 Thanked 8 Times in 7 Posts	rover 75 cdt camshaft sensor voltage I just did a quick check on my rover 75 cdt camshaft sensor voltage after some warm start issues where it recently took 4-5 attempts to start, however it starts well on a cold morning (all renewable items recently serviced, pump is pushing well, car runs beautifully). The voltage on the yellow wire reads only 6.9v during cranking and when idle. Not much change when ignition on with engine not running. I read on another post that it should be reading 9v from the yellow wire, is the low reading indicative of a possible camshaft sensor failure? Ordered new one just in case.

27th February 2017, 21:03	#3
beededea Regular poster 75 connie tourer, MGZT-T Join Date: Mar 2009 Location: Aylsham Posts: 99 Thanks: 9 Thanked 8 Times in 7 Posts	A continuous 6.9v then is faulty...? Last edited by beededea; 27th February 2017 at 21:06..

1st March 2017, 12:19	#5
beededea Regular poster 75 connie tourer, MGZT-T Join Date: Mar 2009 Location: Aylsham Posts: 99 Thanks: 9 Thanked 8 Times in 7 Posts	confused... The new cam sensor arrived (OEM), we installed it, checked the voltage with an analogue multimeter and it was 12v consistently... car still hard to start. Installed the old cam sensor that was reading 6.9v, now reading 12v too. Car still hard to start. Runs beautifully when it catches. Confused. Possibly my old digital multimeter was giving the wrong reading when it said 6.9v, taken that to bits too... Any ideas?

26th July 2018, 16:14	#9
beededea Regular poster 75 connie tourer, MGZT-T Join Date: Mar 2009 Location: Aylsham Posts: 99 Thanks: 9 Thanked 8 Times in 7 Posts	Awakening this post from the dead using the powers invested in me! The previous car that had this problems is dead and gone. Car 1. However the problem has returned on another car. Rover 75 CDT, Car 2... It is a problem. Battery is very good. Car 2 has had a recent service, fuel is good. Generally runs like a train. Plenty of power. The engine is cool from a night's standing but in the warm weather we are experiencing now (summer 2018 34 degrees) the car turns over but will not easily start. After four or five attempts at 10 turns each the car eventually starts. Car 2 then starts and runs with a little initial faltering that quickly disappears. Then runs like a train. Plenty of power. But...when the engine is warm the problem is even worse. Restarting can take 20-30 cranks. I took the cam sensor and placed it into another engine in another car - Car 3. and it started first time so it seems good. To confirm I have tried three cam sensors (one new) in the Car 3 and it starts first time. Makes no difference in car 2 which cam sensor I use. Testing the value at the fuel pressure sensor on the end of the rail next. Any thoughts? __________________ Jobs/repairs so far: Fanbelt pulley seal, steering pump, alternator, UB & in-tank fuel pumps, front wheel bearing, fanbelt x 2, ECU, bonnet pull, air intake concertina modification, upgraded PCV, fuse box brackets, rear bumber cracks welded, new front bumper, rear springs, changed, new intercooler O rings, plenum cleaned and emptied all the time, in-car Android Digital TV/Navall, three new glow plugs.

1st March 2017, 16:45	#8
beededea Regular poster 75 connie tourer, MGZT-T Join Date: Mar 2009 Location: Aylsham Posts: 99 Thanks: 9 Thanked 8 Times in 7 Posts	Have tried it in the freezer, no effect. About to try another cam sensor from a car that starts well. That will give an indication of whether my old cam sensor/new OEM sensor are slightly out of spec. After that I will try the various voltages from other sensors and then the leack back test. I looked into the plenum chamber through my grommetted inspection hole and noticed some damp in the bottom, certainly not swimming but dampish. I'm going to dry out the chamber and check the contacts at the ECU, then the leakback.

26th July 2018, 19:12	#10
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,572 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	An injector leak back test is easy enough to do, and will check if one or more injectors is leaking excessively.