Disco 2 New crank sensor cable?

A bit of background:

I’ve recently changed both gearboxes and have been working on a few gremlins from that - mainly shimming the CPS.
Yesterday, I found that the engine hit a brick wall around 3,000 RPM. A bit of research pointed to the turbo related bits.

Now, I drove it back home keeping around 2,000 RPM and it ran ok. I then got on with fixing gremlins from gearbox change, sticky gearshift and handbrake switch. I know now that I left the handbrake switch unplugged but aside from that, no other electrics touched.

I moved to the engine bay and found a small hole in a vacuum hose from the turbo modulator to the metal pipe below, so I cut off the end and re-attached. I also unplugged a couple of plugs on the air box and inlet hose. These were re-attached.

I went to start the engine and it cranks fast but not a hint of starting. I say it cranks fast because I’ve heard it cranking more slowly whilst having problems with the CPS and the shim.

I know I have problems with the CPS and I’m waiting on a new plug so I can make up a new cable but, it seems strange that the starting issue now seems different to the issues when I had no shim under the CPS. It would try to start then and cranked more slowly - at least to my ears.

I’m going to increase the thickness of the shim and renew the cable and plug but are there any other ideas as to what other reasons might cause this fast cranking with no attempt to fire?

I have Nanocom and will check injectors, fuel pump (recently changed VDO) and cranking speed over the weekend.

Alpinejim said:

other ideas as to what other reasons might cause this fast cranking with no attempt to fire?

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Can you feel any diesel smell at the exhaust while you crank it?

Can’t feel it but I’ll have a smell this evening.

Do your EML and glow plug lights come on when you first turn on the ignition?

Yes, they do. It seems odd but I can’t remember if they are supposed to all go off during cranking or not.

Check the relays near to the ecu, make sure the connections are clean and tight.

wireman said:

Check the relays near to the ecu, make sure the connections are clean and tight.

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Where are relays near the ECU on a D2 ?

the crank sensor being to close wont make any difference....to far away will.

sierrafery said:

Where are relays near the ECU on a D2 ?

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I was going off my experience with a td5 90, where the two yellow relays under the seatbox next to the ecu, can give the symptoms described. I take it D2 relays are in different place?

wireman said:

D2 relays are in different place?

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The ECU is...

Cheers

.... and the relays too

EeEk said:

the crank sensor being to close wont make any difference....to far away will.

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The gearbox is refurbed and came from an early D2, there was no shim. My original gearbox from this facelift had no shim - despite info on here saying that manuals have a shim and autos don’t.

I initially fitted with no shim and had trouble starting. Then I made a .5mm shim and got it to start, though not reliably. I made a 1mm shim and it started much better but sometimes coughed as it started.
Now there’s nothing, not a cough or an EML, which did come on with a thinner shim, which leads me to suspect that, although the CPS and shim are not yet 100%, they are not at fault for this problem.

I have a new connector now so I’m going to make up a new shielded cable and connector this evening and try it with both shims and a second CPS to rule that out.

If you have nanocom connect it, start the engine with spray cos it will run on it few seconds at idle and watch the rpm on nanocom... it should show you around 780 if the CPS signal is OK

I get no smell of deisel at the exhaust, fuel coming out of the line coming to the regulator though. I got no reading at all for engine speed whilst cranking so I'm guessing that the crank sensor/wiring could be the problem and the ECU didn't operate the injectors?

I found some oil in the red plug too so I'm going to replace the injector harness and make a new screened cable from the red plug to the CPS.

Alpinejim said:

I'm guessing that the crank sensor/wiring could be the problem and the ECU didn't operate the injectors?

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I'm guessing that you are guessing right

Alpinejim said:

.... make a new screened cable from the red plug to the CPS.

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read the whole thread https://www.landyzone.co.uk/land-rover/so-called-specialist-garage.255544/page-2#post-4458600 maybe you better buy a well made one for 20 quid

I was going to wait a couple of days before posting this but I’m confident that it’s now fixed.

Pulling out the CPS, I found that one wire was coming out of the back of the plug. This would explain why it previously started, but not reliably and then refused to start at all. With no signal from the CPS, the ECU didn’t fire the injectors which caused the the cranking to sound higher pitched than usual. This lead me to believe that it was a different problem, but was just a deterioration of the actual problem.

I made myself a new cable screened from CPS to ECU.


While I’ve been waiting for the cable, I replaced the injector harness because there was oil in the red plug and the turbo vacuum hoses which caused the problems at 3,000 RPM - I hope.

For reference, I left the 1mm shim in place. I’ll see if it continues to run without problems.

Thanks all for your help.