Strange CDT engine cutout and starting issue - Page 2

Dvorak · 21st July 2016, 13:47

So I couldn't find anything wrong with the pumps or fuel filter. Took it to my local guy, who read the OBD and found a MAF fault. He's now replaced it for me.

Could this have been causing the symptoms I had? Rough idle, stalls, loss of power. I found on the CDT troubleshooting guide that "MAF symptoms are related to poor reving or sudden loss of drive especially in bad weather" - that is exactly what happened to me when I broke down.

I hate intermittent faults because I don't feel I can trust her to take me all the way down the motorway now

.

TomRS · 21st July 2016, 15:16

Quote:

Originally Posted by Dvorak

So I couldn't find anything wrong with the pumps or fuel filter. Took it to my local guy, who read the OBD and found a MAF fault. He's now replaced it for me.

Could this have been causing the symptoms I had? Rough idle, stalls, loss of power. I found on the CDT troubleshooting guide that "MAF symptoms are related to poor reving or sudden loss of drive especially in bad weather" - that is exactly what happened to me when I broke down.

I hate intermittent faults because I don't feel I can trust her to take me all the way down the motorway now

.

Maf sensor can easily cause loss of power, but it shouldnt have an affect on idle... but then if it was really bad i guess it could.
It measures the air going into the car, it adds fuel accordingly so its very possible that all your issues related to a bad MAF however they usually dont fail like that.
If the car runs good now then just enjoy her.

Dvorak · 21st July 2016, 17:39

I was wrong - misheard down the phone.

What was throwing an error and replaced was the MAP sensor, not MAF. I can't find much information about this - is it likely to have caused my symptoms?

Mike Noc · 21st July 2016, 17:56

Quote:

Originally Posted by TomRS

Maf sensor can easily cause loss of power, but it shouldnt have an affect on idle... but then if it was really bad i guess it could.

Stalling at idle was the only symptom when my MAF packed up, but it is rare as I haven't heard anyone else mention it.

klarzy · 21st July 2016, 18:23

Quote:

Originally Posted by Mike Noc

Stalling at idle was the only symptom when my MAF packed up, but it is rare as I haven't heard anyone else mention it.

if the MAF stops working does the MAP sensor in the intake manifold not take over? Not as refined but it should run no??

James.uk · 21st July 2016, 18:46

Sounds like a leakback problem to me... Do the test and report back please.

...

Mike Noc · 21st July 2016, 19:46

Quote:

Originally Posted by klarzy

if the MAF stops working does the MAP sensor in the intake manifold not take over? Not as refined but it should run no??

The ECM will revert to a default map if the MAF is unplugged, but I can only assume that my MAF was giving incorrect readings and this caused the stalling.

fazmg · 22nd July 2016, 02:18

I had a similar problem, when coming to junction's or up hill engine would cut out display low oil pressure plus engine management light. Turned out my in tank pump was giving up and then eventually gave up. Then I also found another fault which was a bad earth from battery to car body to which I had car started and pulled on earth wire and engine cut out. Earth wire had deteriorated from bolt bracket.

There could be many other reasons just like the lads of stated....

Leak back cam or crank sensor hp rail sensor.

The lads on ere have more knowledge they will help you.

Good luck.

Mike Noc · 22nd July 2016, 07:38

Yes could be many things although a failing cam sensor won't cause the cutting out - it is only used at each start up.

And it doesn't sound like injector leakback because the OP said the car cut out and then cut back in again.

I'm sure I read somewhere that if the engine cuts out due to a fall in HP fuel pressure it won't restart unless you turn the key off and back on again.

TomRS · 22nd July 2016, 08:26

As posted above, a failed MAP sensor would cause those issues as that measures manifold pressure.

Without knowing what the pressure is or if the sensor was giving intermitant readings it could literally be shutting off fuel supply and or giving incorrect fuel trim.
This sensor basically measures the boost into the manifold with that replaced and obviously your MAF is fine.

MAF = Mass air flow
MAP - Manifold Absolute Pressure

Both sensors are required to work in tandem, if one fails the other is relied on as a backup however if both sensors are weak then you could run into these issues that you have described.

22nd July 2016, 08:26	#20
TomRS Posted a thing or two Mk1 ZT 190 - Mk2 ZS 180 - Mercedes E63 AMG S - Ford Ranger Hawk Join Date: Mar 2016 Location: Middlesbrough Posts: 1,456 Thanks: 123 Thanked 409 Times in 281 Posts	As posted above, a failed MAP sensor would cause those issues as that measures manifold pressure. Without knowing what the pressure is or if the sensor was giving intermitant readings it could literally be shutting off fuel supply and or giving incorrect fuel trim. This sensor basically measures the boost into the manifold with that replaced and obviously your MAF is fine. MAF = Mass air flow MAP - Manifold Absolute Pressure Both sensors are required to work in tandem, if one fails the other is relied on as a backup however if both sensors are weak then you could run into these issues that you have described. __________________ http://i66.tinypic.com/5cd6xj.jpg

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21st July 2016, 13:47	#11
Dvorak Avid contributor Rover 75 Saloon CDT Copperleaf Red Join Date: May 2013 Location: Cumbria/Oxford Posts: 100 Thanks: 7 Thanked 5 Times in 3 Posts	So I couldn't find anything wrong with the pumps or fuel filter. Took it to my local guy, who read the OBD and found a MAF fault. He's now replaced it for me. Could this have been causing the symptoms I had? Rough idle, stalls, loss of power. I found on the CDT troubleshooting guide that "MAF symptoms are related to poor reving or sudden loss of drive especially in bad weather" - that is exactly what happened to me when I broke down. I hate intermittent faults because I don't feel I can trust her to take me all the way down the motorway now .

21st July 2016, 17:39	#13
Dvorak Avid contributor Rover 75 Saloon CDT Copperleaf Red Join Date: May 2013 Location: Cumbria/Oxford Posts: 100 Thanks: 7 Thanked 5 Times in 3 Posts	I was wrong - misheard down the phone. What was throwing an error and replaced was the MAP sensor, not MAF. I can't find much information about this - is it likely to have caused my symptoms?

21st July 2016, 18:46	#16
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	Sounds like a leakback problem to me... Do the test and report back please. ...

22nd July 2016, 02:18	#18
fazmg Regular poster mg zt cdti Join Date: Dec 2013 Location: west yorkshire Posts: 49 Thanks: 4 Thanked 3 Times in 3 Posts	I had a similar problem, when coming to junction's or up hill engine would cut out display low oil pressure plus engine management light. Turned out my in tank pump was giving up and then eventually gave up. Then I also found another fault which was a bad earth from battery to car body to which I had car started and pulled on earth wire and engine cut out. Earth wire had deteriorated from bolt bracket. There could be many other reasons just like the lads of stated.... Leak back cam or crank sensor hp rail sensor. The lads on ere have more knowledge they will help you. Good luck.

22nd July 2016, 07:38	#19
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: 11,547 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	Yes could be many things although a failing cam sensor won't cause the cutting out - it is only used at each start up. And it doesn't sound like injector leakback because the OP said the car cut out and then cut back in again. I'm sure I read somewhere that if the engine cuts out due to a fall in HP fuel pressure it won't restart unless you turn the key off and back on again.