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blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17202

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

hornet wrote:
Interesting, I had previously assumed that the crankshaft sensor was only required for "normal" starting with the starter motor. I often roll slightly down the hill in the morning and let the clutch come in, the engine starts immediately without any turns and without delay. So I bet it would do that without crankshaft sensor at all....

The crankshaft sensor is the *only* mechanism for the ECM to determine the firing point for the injectors. Without it injection timing is impossible and the engine cannot under any circumstances run.

The camshaft position sensor is only needed because since the engine has a four stroke Otto cycle, there are two rotations of the crankshaft for each cylinder's power stroke. The camshafts are of course geared to rotate once for every two rotations of the crankshaft and therefore the camshaft position sensor allows the ECM to determine whether the crankshaft is on the compression or exhaust stroke and fire the injector at the right time. Once the ECM has determine this it effectively synchronises to alternate crankshaft sensor pulses and runs quite happily without further reference to the camshaft sensor.

It would be technically possible to programme an ECU to run with only a camshaft sensor but not with only a crankshaft sensor, however in the interests of accurate timing (and therefore smooth running, fuel efficiency, and cleanliness) this is never done.

You can try this out if you want to by unplugging the camshaft sensor and seeing if you can get the engine running properly by any means. I would be very surprised if you can.

I think that "IFS" in this context stands for "Inertia Fuel Switch" or Inertia Fuel Shut-off". The 2.2 has one but not the 2.4 so this is not going to be the OP's issue. It is conceivable that it could cause this problem on a 2.2, since the engine pump may well still be able to pick up fuel if the engine is running properly (just as it does on the 2.4, albeit with a different fuel pump).

13th Jun 2024 3:19pm

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 406

A while back I was checking the camshaft and crankshaft signals..
What I will do at some point is get a reference for say No1 cylinder firing.. I only have a two channel scope but once I know where the firing position of no 1is relative to the above signals it may be handy in checking timing issues..
Again a photo of the crankshaft against camshaft... Covering a couple of engine revolutions..

Click image to enlarge

13th Jun 2024 4:06pm

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 406

Sorry.. This is the trace covering the two engine revolutions👍🙈

Click image to enlarge

13th Jun 2024 4:10pm

Simo74

Member Since: 11 Jun 2024
Location: Bathurst
Posts: 5

2008 Defender 130 Puma 2.4 HCPU Alaska White

Note. I replaced the VCV after the no start issue
I tried leaving it with the battery disconnected for 24 hrs, new battery in the fob, reconnect and no start
Still starts with ether fine, ran it for about 20 mins at about 1500rpm, could get it to about 900 and it stalls!!!

I will get a new crank and cam sensors just to eliminate

Thanks for the advice so far 👍

14th Jun 2024 6:08am

andy63

Member Since: 30 Jun 2023
Location: north east
Posts: 406

Aside from the not starting normally, the fact it runs but just won't run at low revs would take me back to a fuel issue.. I can't see that been cam or crank related..
With the absence of any current codes
I would however have a look at as many of the input signals like air, fuel, coolant temp along with map acc pedal position, maf etc to see if any looked odd..
Hope you have some sucess👍

14th Jun 2024 11:36am

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20096

VCV, fuel pump or injectors.
You really need to find out what pressure there is being produced via diagnostics.
It’d be worth checking you are getting appropriate alternator voltage as well during the time it is running.
Any signs of leaks near the injectors? NEVER SURRENDER! ⛽️🛢️👨‍🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧

14th Jun 2024 11:52am

hornet

Member Since: 04 Jan 2010
Location: Western Europe
Posts: 357

blackwolf wrote:
[...]

You can try this out if you want to by unplugging the camshaft sensor and seeing if you can get the engine running properly by any means. I would be very surprised if you can.

You are absolutely right, it will not start with a disconnected crankshaft sensor. I expected that but was curious...

23rd Jun 2024 1:01pm

Simo74

Member Since: 11 Jun 2024
Location: Bathurst
Posts: 5

Blackwolf- when I replaced vcv I left the connect the cam position off and the engine will not start even with ether injection.
Reconnecting the cam sensor allowed it to start over 1000 rpm
I have replaced the crank angle sensor and it started like a new car!

9th Aug 2024 11:44pm

Simo74

Member Since: 11 Jun 2024
Location: Bathurst
Posts: 5

With the vehicle running great I have taken it cross country, 3000ks in the journey check engine light came on with very limited performance
Egr p0404 performance issues
Reset the system by locking the car and coming back to it 10 mins later and it was fine.
500ks later same fault code with limited performance in the low rev range, after 2k boost comes on and performance is okay, just no low rpm boost?..

Can’t shake this performance issue

I have blocked the Egr now and the low rpm performance is still poor

Amy ideas

9th Aug 2024 11:52pm

MK

Member Since: 28 Aug 2008
Location: Santiago
Posts: 2394

2007 Defender 110 Puma 2.4 SW Chawton White

How did you "block" the EGR? Puma 110" SW

.............................................................
Earth first. Other planets later

10th Aug 2024 12:02am

jbcollier

Member Since: 29 Apr 2024
Location: Edmonton AB
Posts: 50

2009 Defender 110 Puma 2.4 SW Alpine White

After replacing my head, it also would not start. I bled the fuel system and it started right up.

11th Aug 2024 1:28pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20096

That’s what you’ve got to be careful of when changing the fuel filter too, hence the fully fill fuel filter before fitting and swapping it which is not a problem at all.

NEVER SURRENDER! ⛽️🛢️👨‍🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧

11th Aug 2024 4:18pm

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