cdti occasional rough running, now won't start

martin2010 · 11th July 2020, 13:10

My cdti has had a couple of rough starts over the last week, this has gone away after about 10 minutes of driving and doesn't come back again on a return journey.

Today I went out to move the car and it wont start at all, it turns over but it just won't catch.

I have taken a look at the injectors and they were dirty and the inlet manifold is really dirty inside, i sprayed carb cleaner onto the injectors to get some of the gunk off them.

I assume this isn't a maf problem as it wont start at all now.

The car does have the second fuel pump in the engine bay which sounds like it's working just fine.

Yorkshire GOC · 11th July 2020, 14:07

When you turn her over does the rev counter move at all - if it does not that points to a failed/failing crankshaft sensor which can cause non starts and poor running.

martin2010 · 11th July 2020, 15:17

yes the rev counter jumps up a little bit.

i've just took a look at the plenum and there was a bit of water in there, not up to the level of the ecu housing but enough that the pollen filter was wet. i have now drained that out. No condensation inside the black housing of the ecu either.

Yorkshire GOC · 11th July 2020, 15:21

So that indicates your crank sensor is operative. By rough running what is she doing ?

COLVERT · 11th July 2020, 16:36

Quote:

Originally Posted by Yorkshire GOC

So that indicates your crank sensor is operative. By rough running what is she doing ?

The OP says in his post that the engine is not running at all.---

martin2010 · 11th July 2020, 16:39

It was almost like the car was close to stalling. You could feel it vibrating through the wheel as well like maybe it wasn't running a cylinder properly.

It wasnt all the time when it did it however which is why im puzzled

Yorkshire GOC · 11th July 2020, 17:45

2 things come to mind - fuel injectors playing up - you may need to do the leak back test - or have a look at your ECU - you mentioned a wet pollen filter - have a look to see if any moisture ingress - tide marks or rusting on the ECU itself.

Retap · 29th March 2021, 15:54

Quote:

Originally Posted by Yorkshire GOC

When you turn her over does the rev counter move at all - if it does not that points to a failed/failing crankshaft sensor which can cause non starts and poor running.

Excuse me barging into somebody elses thread but can i get clarification on this business with the rev counter and cam sensor.

My situation is had have intermittent none starting from both colc and warm since buying the car 2 years ago and today it has occurred just after filling the car with tip bound junk and now the tip is closed all week as couldnt get down before closing today because of none start, which is nice and makes me love my MG more than usual today.

I came across this info months ago and have noted since then when I crank there is never any movement on the rev counter just like todays no start from cold. Im going out now to try again and pretty sure it will start first try as it always does after an hours rest or when it senses i no longer care.

Retap · 29th March 2021, 16:47

So yeah starting first try just now as predicted, the only change being a slight dip in ambient temp as the sun drops lower and it has been hottest day of the year so far today reaching a whopping 24 Deg C but i feel the straws clutching. My tourer doesnt like me does it, or the tip runs, not ruling out both actually

btw the sticky for none starting cdti was interesting, got a feeling i will be needing that again v soon. Leak back test next up then followed by cam sensor or crank sensor maybe both.

https://www.the75andztclub.co.uk/for...ad.php?t=22402

Mike Noc · 29th March 2021, 17:21

Quote:

Originally Posted by Retap

Excuse me barging into somebody elses thread but can i get clarification on this business with the rev counter and cam sensor.

Yes the cam sensor has nothing to do with rev counter whatsoever. The crank sensor provides the rev counter signal via the ECM.
If you have problems starting but once started the engine runs fine then a possible cam sensor fault as it is only used to reference the cam position from rest. Once started the ECM ignores the cam sensor until the next start up.

The crank sensor is used constantly by the ECM to time the fuel injection so any problems with it can cause cutouts and running problems.

11th July 2020, 13:10	#1
martin2010 Newbie vauxhall meriva Join Date: Aug 2015 Location: birmingham Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	cdti occasional rough running, now won't start My cdti has had a couple of rough starts over the last week, this has gone away after about 10 minutes of driving and doesn't come back again on a return journey. Today I went out to move the car and it wont start at all, it turns over but it just won't catch. I have taken a look at the injectors and they were dirty and the inlet manifold is really dirty inside, i sprayed carb cleaner onto the injectors to get some of the gunk off them. I assume this isn't a maf problem as it wont start at all now. The car does have the second fuel pump in the engine bay which sounds like it's working just fine.

11th July 2020, 14:07	#2
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,067 Thanks: 1,842 Thanked 623 Times in 469 Posts	When you turn her over does the rev counter move at all - if it does not that points to a failed/failing crankshaft sensor which can cause non starts and poor running. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

11th July 2020, 15:21	#4
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,067 Thanks: 1,842 Thanked 623 Times in 469 Posts	So that indicates your crank sensor is operative. By rough running what is she doing ? __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

11th July 2020, 17:45	#7
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,067 Thanks: 1,842 Thanked 623 Times in 469 Posts	2 things come to mind - fuel injectors playing up - you may need to do the leak back test - or have a look at your ECU - you mentioned a wet pollen filter - have a look to see if any moisture ingress - tide marks or rusting on the ECU itself. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

29th March 2021, 16:47	#9
Retap Loves to post MG ZT-T CDTi Join Date: Sep 2020 Location: Lincs Posts: 288 Thanks: 73 Thanked 51 Times in 44 Posts	So yeah starting first try just now as predicted, the only change being a slight dip in ambient temp as the sun drops lower and it has been hottest day of the year so far today reaching a whopping 24 Deg C but i feel the straws clutching. My tourer doesnt like me does it, or the tip runs, not ruling out both actually btw the sticky for none starting cdti was interesting, got a feeling i will be needing that again v soon. Leak back test next up then followed by cam sensor or crank sensor maybe both. https://www.the75andztclub.co.uk/for...ad.php?t=22402 __________________ ZT-T Mk2 Jobs to do: Renew auxiliary drive belt # Replace driver door lock actuator # Refurbish wheels

11th July 2020, 15:17	#3
martin2010 Newbie vauxhall meriva Join Date: Aug 2015 Location: birmingham Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	yes the rev counter jumps up a little bit. i've just took a look at the plenum and there was a bit of water in there, not up to the level of the ecu housing but enough that the pollen filter was wet. i have now drained that out. No condensation inside the black housing of the ecu either.

11th July 2020, 16:39	#6
martin2010 Newbie vauxhall meriva Join Date: Aug 2015 Location: birmingham Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	It was almost like the car was close to stalling. You could feel it vibrating through the wheel as well like maybe it wasn't running a cylinder properly. It wasnt all the time when it did it however which is why im puzzled