Rover 75 V6 2.5 no spark when hot.

[krqkan]

-- I've googled like a maniac but people only say "Check for FFS/FOC, or camshaft sensor" - all been done, not the problem.--

Hiya!

So ive got a Rover 75 2.5 v6 -02 that suffers from an odd problem.
There is no spark when the car is hot. It just turns and turns, sometimes you get lucky and the thing starts but mostly i have to wait from around 5 min to bout 40+ min.

So ive googled and googled.
Got a new Cam sensor, pluged a leak in the vacuum pipes (plastic t joint broke) checked the fuel filter (old model).

And i was talking to my co-workers and they suggested that it could be that the engine gets to much fuel when hot (he had a volvo 740 with this problem) so i was just about to remove the sparkplug and check if it was wet when my father came by with a new sparklpug and said "lets check if its sparks" and so we did and found out it doesn't.

Any ideas on what could be the problem?

So to sum it all up:

New camshaft sensor
Fixed Vacuum leak
Checked fuel filter
Found out there is no spark when turning if hot (not always)

Cheers

/Richard.

[MrDoodles]

I'm not currently at my PC, do they have a crank sensor?

[krqkan]

I'm not currently at my PC, do they have a crank sensor?

I think they do.
But crank should only be for when running and cam for when starting. If i haven't got it totaly wrong.

[SD1too]

But crank should only be for when running and cam for when starting.
According to MG Rover's manual, both crankshaft and camshaft position sensors are required for starting.

Simon

[MangoMan]

-- I've googled like a maniac but people only say "Check for FFS/FOC, or camshaft sensor" - all been done, not the problem.--

Hiya!

So ive got a Rover 75 2.5 v6 -02 that suffers from an odd problem.
There is no spark when the car is hot. It just turns and turns, sometimes you get lucky and the thing starts but mostly i have to wait from around 5 min to bout 40+ min.

So ive googled and googled.
Got a new Cam sensor, pluged a leak in the vacuum pipes (plastic t joint broke) checked the fuel filter (old model).

And i was talking to my co-workers and they suggested that it could be that the engine gets to much fuel when hot (he had a volvo 740 with this problem) so i was just about to remove the sparkplug and check if it was wet when my father came by with a new sparklpug and said "lets check if its sparks" and so we did and found out it doesn't.

Any ideas on what could be the problem?

So to sum it all up:

New camshaft sensor
Fixed Vacuum leak
Checked fuel filter
Found out there is no spark when turning if hot (not always)

Cheers
/Richard.

Camshaft Sensor. Under Engine Cover to the right of the Oil Filler Cap.
Very common problem and are available at Rimmers. The New ones are 2 part type, Sensor and Cable.
There are 2 types of leads, one has theories wired differently and make it not work.Make sure the Sensor is seated properly with only one rubber washer.
Cheers.

PS. If it was the Crank Sensor it wouldn't run at all.

[krqkan]

According to MG Rover's manual, both crankshaft and camshaft position sensors are required for starting.

Simon

crank only tells when its time to inject fuel. It gets fuel, no spark.
And when it runs, it runs perfectly.


Camshaft Sensor. Under Engine Cover to the right of the Oil Filler Cap.
Very common problem and are available at Rimmers. The New ones are 2 part type, Sensor and Cable.
There are 2 types of leads, one has theories wired differently and make it not work.Make sure the Sensor is seated properly with only one rubber washer.
Cheers.

PS. If it was the Crank Sensor it wouldn't run at all.

Camshaft was the first thing i changed.
and the new part was an original Rover NSC 100 610 M

[ProfDave]

coil pack?? Only say this as I had a really irritating hot running problem on my mini which I put electronic ignition on; after two years of fuel related fiddles I changed the coil (which was a new one not long before the problems started)

seems that some of the coil innards were separating at high operating temps giving uneven spark



just a thought as obviously the engine types and three generations apart!

[krqkan]

coil pack?? Only say this as I had a really irritating hot running problem on my mini which I put electronic ignition on; after two years of fuel related fiddles I changed the coil (which was a new one not long before the problems started)

seems that some of the coil innards were separating at high operating temps giving uneven spark



just a thought as obviously the engine types and three generations apart!

is there any easy way to check if that's the problem?

A new set of 6 coils is about £200. And i don't want to throw that kind of money on a broken car if the coils aint the problem :P

Edit: If it was the ignition coils, then it would mean that all 6 of em are broken. If one was broken it would fire up on 5 cylinders.

Could it be some kind of distributor for the coils, or maybe a faulty signal from ECU?

[VMax1000]

Crank and cam sensor are both required for starting. If the cam sensor fails during driving the car will be dead. If the crank fails however the ECU goes to a fixed ignition advance based on the cam sensor.

So if the crank sensor fail the car will still run until switched off. Won't restart until cold.

Had the same problem on the wifes Alfa. Crank sensor solved the problem
(just as well as cam sensor means timing belts off on the Alfa :()

[krqkan]

Crank and cam sensor are both required for starting. If the cam sensor fails during driving the car will be dead. If the crank fails however the ECU goes to a fixed ignition advance based on the cam sensor.

So if the crank sensor fail the car will still run until switched off. Won't restart until cold.

Had the same problem on the wifes Alfa. Crank sensor solved the problem
(just as well as cam sensor means timing belts off on the Alfa :()

"
So if the crank sensor fail the car will still run until switched off. Won't restart until cold."

Ah, that might be it then! :D
Thought the crank sensor only were in use during running.

Any good guides with images on how to change it on a V6?

[kaiser]

The crank sensor is the important one. this is the one that must work, or the engine will not run.
The coil packs would not all fail at the same time, so no point in suspecting them all.

Replacing the crank sensor would be the next logical step, I would say.

In my old SDE, the amplifier in the ignition system would sometimes do just this, go on strike when hot, only to then fail permanently quite a while after.

[krqkan]

The crank sensor is the important one. this is the one that must work, or the engine will not run.
The coil packs would not all fail at the same time, so no point in suspecting them all.

Replacing the crank sensor would be the next logical step, I would say.

In my old SDE, the amplifier in the ignition system would sometimes do just this, go on strike when hot, only to then fail permanently quite a while after.

how can i tell which sensor to get without removing it to check part no?
Maby get the engine model or something?

[VMax1000]

how can i tell which sensor to get without removing it to check part no?
Maby get the engine model or something?

Just out of curiosity, but what is the difference between a crank sensor and a crank pulse sensor. Does the KV6 has both?

http://www.crankshaftsensors.co.uk/Parts.aspx?s_vm=ROVER&s_vmod=75&s_vs=2.5 V6&s_ec=KV6&s_pt=Crankshaft Pulse Sensor

http://www.crankshaftsensors.co.uk/Parts.aspx?s_vm=ROVER&s_vmod=75&s_vs=2.5%20V6&s_ec=KV6&s_pt=Crank%20Sensor

[krqkan]

Just out of curiosity, but what is the difference between a crank sensor and a crank pulse sensor. Does the KV6 has both?

http://www.crankshaftsensors.co.uk/Category.aspx?s_vm=ROVER&s_vmod=75&s_vs=2.5 V6&s_ec=KV6

No clue.
Guessing its the same thing just different names. Maby?

[T-Cut]

They have a crankshaft position sensor and a camshaft position sensor. They are different parts and do different things.

Here's the Xpart/Rimmer listing for Part Numbers: http://www.rimmerbros.co.uk/Item--i-GRID001630

TC

[okenora]

odds with paddy power on this one are odds on for crank sensor. Typical failure scenario for it to work when cold then fail when warm, preventing warm starts. Not an exclusive Rover problem either, load of makes follow this pattern of failure when hot.

it is part 6 in this diagram (http://www.rimmerbros.co.uk/Item--i-GRID001630)

At least 2 different types were used. One had a flying lead to connect with, the other had the loom plug in directly to a socket on the sensor. AFAIK the flying lead type is no longer available and you may have to buy the lead to connect to the loom seperately, the scrappies may be your best friend for that

[SD1too]

how can i tell which sensor to get ...
When the fault occurs, you might like to check that your CKP sensor is receiving a power supply and earth connection before spending money on a replacement.

Simon

[krqkan]

They have a crankshaft position sensor and a camshaft position sensor. They are different parts and do different things.

Here's the Xpart/Rimmer listing for Part Numbers: http://www.rimmerbros.co.uk/Item--i-GRID001630

TC

odds with paddy power on this one are odds on for crank sensor. Typical failure scenario for it to work when cold then fail when warm, preventing warm starts. Not an exclusive Rover problem either, load of makes follow this pattern of failure when hot.

it is part 6 in this diagram (http://www.rimmerbros.co.uk/Item--i-GRID001630)

At least 2 different types were used. One had a flying lead to connect with, the other had the loom plug in directly to a socket on the sensor. AFAIK the flying lead type is no longer available and you may have to buy the lead to connect to the loom seperately, the scrappies may be your best friend for that

When the fault occurs, you might like to check that your CKP sensor is receiving a power supply and earth connection before spending money on a replacement.

Simon

But shouldn't i experience problem with the car while running if its the crank sensor?

[VMax1000]

But shouldn't i experience problem with the car while running if its the crank sensor?

My understanding always has been that the crank sensor is pulsed multiple times during one revolution whereas the cam sensor only provides one pulse per revolution.

This one pulse indicates where the cylinders are and provide info for injection and spark. The crank sensor is sometimes used for rev-counter and spark advance and injector opening times.

If the crank sensor fails the car will go into limp mode calculating everything from the cam-sensor as this indicates Top Dead Centre or cylinder position.

Hence a cam sensor fail will stop the car dead and a crank sensor fail will prevent it from starting when hot but allow to start when cold (unless completely dead)

Of course I'm happy to be corrected but this was the case on the Alfa 147 we have. Wouldn't start when hot, then when cold would start and run. Finally the sensor failed and the car wouldn't start. Replaced the crank sensor and all is fine since then :)

[SD1too]

But shouldn't i experience problem with the car while running if its the crank sensor?
Ever heard of an intermittent fault Richard? :D

Simon

[Mike Noc]

My understanding always has been that the crank sensor is pulsed multiple times during one revolution whereas the cam sensor only provides one pulse per revolution.

This one pulse indicates where the cylinders are and provide info for injection and spark. The crank sensor is sometimes used for rev-counter and spark advance and injector opening times.

If the crank sensor fails the car will go into limp mode calculating everything from the cam-sensor as this indicates Top Dead Centre or cylinder position.

Hence a cam sensor fail will stop the car dead and a crank sensor fail will prevent it from starting when hot but allow to start when cold (unless completely dead)

Different engines use the cam and crank sensors signals in different ways.

The KV6 is a very good example as, according to the Rover documentation, the earlier ones had a sequential cam sensor and so the engine could run in limp mode with a failed crank sensor, but did need the cam sensor signal to start.

The later ones had the halfmoon cam sensor, so could start with no cam sensor signal, but if the crank sensor failed the engine would stop.

Many engines just use the cam sensor to detect where the cam is in relation to the crank at start up as it only revolves at half the crankshaft speed, then use the crank signal to time the injectors and sparks. The crank signal is far more accurate as it is coming directly from the crank so not affected by cambelt/camchain flutter or stretch.

[VMax1000]

Different engines use the cam and crank sensors signals in different ways.

The KV6 is a very good example as, according to the Rover documentation, the earlier ones had a sequential cam sensor and so the engine could run in limp mode with a failed crank sensor, but did need the cam sensor signal to start.

The later ones had the halfmoon cam sensor, so could start with no cam sensor signal, but if the crank sensor failed the engine would stop.

Many engines just use the cam sensor to detect where the cam is in relation to the crank at start up as it only revolves at half the crankshaft speed, then use the crank signal to time the injectors and sparks. The crank signal is far more accurate as it is coming directly from the crank so not affected by cambelt/camchain flutter or stretch.

Thanks for that, after a previous reply I thought I lost the plot:}

[krqkan]

My understanding always has been that the crank sensor is pulsed multiple times during one revolution whereas the cam sensor only provides one pulse per revolution.

This one pulse indicates where the cylinders are and provide info for injection and spark. The crank sensor is sometimes used for rev-counter and spark advance and injector opening times.

If the crank sensor fails the car will go into limp mode calculating everything from the cam-sensor as this indicates Top Dead Centre or cylinder position.

Hence a cam sensor fail will stop the car dead and a crank sensor fail will prevent it from starting when hot but allow to start when cold (unless completely dead)

Of course I'm happy to be corrected but this was the case on the Alfa 147 we have. Wouldn't start when hot, then when cold would start and run. Finally the sensor failed and the car wouldn't start. Replaced the crank sensor and all is fine since then :)

Okey! :D
Ill try changing it.
Ever heard of an intermittent fault Richard? :D

Simon

Actually no. First time I've heard that word haha ;D
But after google translating it i guess you could be right ;)

Ill try changing it.