75 CDT no-start+ crazy diagnostic technique?

[Trisman]

I'm wondering if my 'new' off-the-wall diagnostic technique is plausible in any way...!

Background:

My 2000 Diesel CDT has been running very well, not used all that much TBH., but today...

Pulled over at a service station to get some refreshments. After about 15~20 minutes, went to start the car & it refused to start, though it did turn-over fine.

Usually, it starts first turn of the key.....

I bought some evil EaziStart from the station & gave it a try.

It would catch but wouldn't keep running. (ie: It ran on the EaziStart, not diesel).

I waited a further half hour, still no luck so called Green Flag.

Another hour or so & he arrived. Tried again, turned over, no start.

Fuel flow checked (was fine BTW), both pumps seem to be working, cracked a connection at an injector, fuel flowing there too.

Tried to start again & it fired straight-up! A few repeat tests & it's starting fine.

A bit of head scratching followed because he admitted that he hadn't done anything that should really have made any difference...

Possibly it had cooled enough for *whatever* to rectify itself?

Drove back home without issue, car running fine. Got home, switched off & when tried after a minute or two, it immediately restarted.

Left it for an hour or so & have just been out to see if it'll restart.


Nothing. Just turns over without any attempt to start.

A quick look on 'ere suggested a few possible causes, one of which is the cam sensor.


The mad idea....

Then it came to me... Eazistart is very volatile.

So I tried to start the car, still nothing. Then I sprayed some Eazistart onto the cam sensor until it was cold to the touch & tried again.

It started first turn of the key!

So, new cam sensor time?

(Thinking about this, I've been using the car recently in a way that either allows it to cool-down completely between starts or it's restarted almost immediately, so this possible issue with the cam sensor might have been masked by usage patterns?).

Digressing slightly, does a cam sensor fault show-up on a T4 scan?

Also, any T4 Guru's who can do a 160 remap anywhere near Chichester..?

(Needs to be done!).

[Mike Noc]

Sounds like a faulty cam sensor and yes T4 will pick it up.

[marinabrian]

T4 will identify a cam sensor fault, however here is a puzzler for you

The CMP is referenced against the CKP only to synchronise the first injection pulse and the CKP signal is used for run purposes, the CMP is completely disregarded until the next start.

So if you dose a diesel with easistart it will start and continue to run irrespective of CMP failure or not, provided the CKP signal is present

I might go out a limb and suggest you take a look in your plenum to see if it's dry in there

Brian

[Arctic]

Originally Posted by marinabrian

T4 will identify a cam sensor fault, however here is a puzzler for you

So if you dose a diesel with easistart it will start and continue to run irrespective of CMP failure or not, provided the CKP signal is present

I might go out a limb and suggest you take a look in your plenum to see if it's dry in there

Brian

Hi Brian
Did you pick up the PM & email I sent you with regards to a similar situation on a friend of my sons car, I think he may have rang you. ?
if not I have just re-sent it could you please take a look when you have time cheers Arctic.

[Trisman]

Originally Posted by marinabrian

I might go out a limb and suggest you take a look in your plenum to see if it's dry in there

Brian

One of the first mods was an access hole & a handy poking-stick!

(I checked the plenum at the service station. I thought the same after last nights downpour! All dry).

I'll see how the car starts tomorrow morning after a night to cool down.

[Mickyboy]

Originally Posted by marinabrian

T4 will identify a cam sensor fault, however here is a puzzler for you

The CMP is referenced against the CKP only to synchronise the first injection pulse and the CKP signal is used for run purposes, the CMP is completely disregarded until the next start.

So if you dose a diesel with easistart it will start and continue to run irrespective of CMP failure or not, provided the CKP signal is present

I might go out a limb and suggest you take a look in your plenum to see if it's dry in there

Brian

Just as a sideline note I find Freezer spray is handy in some CMP testing situations mate, obviously only for emergency use
Mick

[Mike Noc]

Originally Posted by marinabrian

The CMP is referenced against the CKP only to synchronise the first injection pulse and the CKP signal is used for run purposes, the CMP is completely disregarded until the next start.

So if you dose a diesel with easistart it will start and continue to run irrespective of CMP failure or not, provided the CKP signal is present

Brian

There are engines that can start without synchronising the camshafts to the crankshaft by adjusting the injection timing by 180 degrees if it initially fails to start, but as far as I know the M47R wasn't one of them Brian?

If you dose it with Easystart at what point does the ECM start firing the injectors if the CMP signal is not referenced - is it related to engine speed or number of revolutions?

With no CMP to ensure initial synchronisation it is 50/50 as to whether the injectors fire on the compression stroke, and on our diesel engines if they fire 180 degrees out they won't run in a month of Sundays as it will be injecting fuel near the top of the exhaust stroke.

Not a problem with two-stroke diesels of course.


.

[Trisman]

Update: It started first turn of the key after cooling down overnight.

After a 15 mile run & a 20 minute stop, same thing, an instant start.

Another couple of miles and a 5 minute stop, it only just started, stalled & restarted after about another 5 seconds cranking.

In all cases it drove fine once it was started.

It's interesting what's been said about referencing and synching between cam & crank sensors.

FWIW., mine definitely wasn't going to keep running after a dose of Eazistart into the inlet manifold.

It only ran for about 3 or 4 seconds on Eazistart, which would have been more than enough on other diesel vehicles I've had which showed a reluctance to start. (usually from cold though, such as an LDV van which would be fane all day after an initial cold-engine does of Eazistart... Never did work that one out!).

I am going to get a new cam position sensor & have contacted Phil T4 about a code read & a remap.