Td5 engine does not start after flywheel replacement

Hi there!


Still fighting Td5 - currently with crankshaft sensor issues. Posted 10AS issues some days ago but at the moment this is actually not that relevant.

Although topics regarding crank shaft position CKP adjustment have been debated that often I just wanted to post what I discovered.


With the knowledge how the ECU determines not only TDC (top dead center) in general but also especially distinguishes between injection TDC and changeover TDC and this way worn flywheel can cause massive engine problems I replaced the original fitted dual mass flywheel some days ago against a brand new one. The spring assembly inside of old one seemed to be entirely worn or crushed (hard stop and creaky noise inside clearly felt; as well as brown powder spread on inner recessed surface). The make is Valeo for both old and new one.

After having everything reassembled to my astonishment the engine did not start at all.

Fitted a another CKP which I had fortunately “on stock”.
Engine starts but I had the feeling that I had to crank a bit longer than I remember I did before the repair. Engine idles and runs quite proper but when it is at operating temperature the rougher it runs (idles again like a bag of nuts… or spanners… or what ever).

Plugging a Hawkeye tester (I’ve also a PC-based Faultmate MSV-2; this is in Cyprus at the moment to have it “repaired” once again) I discovered the fault message “High speed crank synch loss logged”.
Then fitted a thin copper washer of 1 mm (as I do not have the NSJ000010 shim) under both CKPs.
Result: Engine starts with above mentioned delay only on that CKP I fetched from stock (NO start possible also on previous mounted one). Message still remains.

Though ohmic coil resistance it selves is not the only criteria for a well working CKP (as a coil and permanent magnet work together) I’ve measured both CKP’s just to make sure the old one is not at fault (winding interuption/short?) :

New one (engine starts with): 1212 Ohms
Prior fitted one (engine does not start with): 1335 Ohms
See photographs (genuine fitted one with label on)

Then put the old flywheel into a lathe, both CKP’s one by one fitted to tool holder with bracket and leads connected to oscilloscope: no significant difference in the oscillogram (distance set from sensor end to flywheel circumference to approx. 1,5 mm as it should be).

Is there anybody there who is well versed in CKP adjustment practice? Do flywheels and CKP have such tolerances? Do CKP olden with time?
Did I forget anything?

Slightly becoming desperate…

Thanks and regards,
Ploughman

never heard of an issue with positioning of sensor ive even made up 300 tdi flywheels with cut down bolts to trigger sensor when converting edc auto to manual,making gap as small as possible ,are you sure wirings not damaged its easy done i know from experience

Ok - so I'll have this checked once again.

Thx,
Ploughman

Unplugged red ECU connector.

Resistance C0158-13 against C0158-36 same as mentioned in first post.
Both against wire screen C0158-16 infinite.
Connection to ground none of them.

measure voltages on the output while cranking... and make sure your battery is FULLY charged, that's very important... if you'll not get voltages within those limits it will not behave well

The ECM measures the outputs from the CKP. The ECM measures the positive signal from the CKP at pin 13 of ECM
connector C0158. The ECM measures the negative signal from the CKP at pin 36 of ECM connector C0158. The earth
path is via pin 16 of ECM connector C0158.
Voltage generation from the CKP sensor is relative to engine speed. The values expected from a good CKP sensor
are as follows:
l 2 to 3 volts with engine cranking.
l Rising to 6 to 6.5 volts from 1000 rev/min upwards.
The above readings are dependent upon correct air gap between the tip of the CKP sensor and the passing teeth of
the reluctor ring.

Click to expand...

As mentioned a draining battery or something that is making the starter motor draw more current.

It happened on track car I was building where during cranking the voltage dropped so low the ecu suffered and struggled to start the engine for the initial large current draw of the starter.

To confirm I tried running a seperate battery for the starter power and the issue went away.