There is a description for a Theft Alarm in the ETM. Says it will kill the engine if below 300 rpm, but no effect over 300 rpm. Only it is written in the Diesel section? Maybe you have something like that going on.

Have you checked the gap between the reluctor and the pickup in the distributor? That pulse is somewhat weaker at low rpm, especially if the gap is on the wide side. But if you get spark while cranking, then the gap is OK.

 

I'll look into those, thanks.

 

Here's what I've done recently in search of the 'root cause' for my '95 Disco 1; "Prolonged cranking before eventual start" (as described by KAR1179 above).

In chronological order:
1) I plugged a Noid light into the injector connector (Cyl # 3 - it was the easiest to get to, and could be seen from the drivers seat when cranking the engine!). Perfect correlation between; no-light, no start and then eventually it fires and the noid light - lights up. This proved to me that the problem is; the fuel injectors are not pulsing. Next step 'why'. (I then did the same test with my '94 Defender which start's fine, same correlation, fired straight with the noid light flashing straight away).
2) I then inserted a Power Probe into Pin 11 (and then 13) at the ECU and the LED starts pulsing immediately I start cranking (but the noid light at the injector isn't flashing and the trucks not starting - not for at least 5-6sec which is my typical delay time in starting). I conclude from this that the ECU is ok (which I already proved about 2 years ago when I swaped it with the Defender ECU and found no change). So my question is 'why' the delay between a pulsing (grounding) ECU and the fuel injector starting to pulse (and inject fuel and permit the truck to start)? Is it 'supply' to the injector OR on the 'Ground' side of the injector.
3) I then measured voltage at the ECU pins of the Disco 1 - see below. The 10V at 11 & 13 while cranking stood out to me as being possibly 'low' and 'supply' side problem- but I don't know, so I established a correlation in measuring an equally low voltage feeding the Fuel Inj. (see below 9.8v), and then thinking I was onto something went and compared it to the Defender which measured 9.5v during cranking and fires straight up immediately (even lower than the Disco 1!) - I have to conclude there's nothing wrong with the 10v at the injector during cranking or the Defender's not bothered by it for starting-up).
4) I'm now loosing hope (a little) for what to do next; my thoughts are to investigate the ground side integrity of the injector which eventually grounds (through the ECU) and back to E100 if I'm not mistaken, which is behind the battery. Before, checking this ground out I will try and located a Power Probe 4 which has a Fuel Inj. function and will confirm the ground integrity (as well as pulse width which would be interesting to know and to compare with the starting Defender).

Any constructive / knowledgeable comments or observations would be much appreciated. Thxs, Ian

 

My 94 14CUX takes longer cranking time before firing than my 96 GEMS. I figure that's just how they are programmed.

 

My 94 14CUX Defender fires up immediately. My 95 14CUX Disco used to fire up a lot quicker than it does now, so I don't believe it's just a programming issue.

 

fyi - I plan to use the fuel injector function on a 'Power Probe 4' this afternoon to measure the 'ground side' integrity and 'pulse width' of injector # 3 during cranking and running and compare it to the Defender readings. If I don't see a difference between them, I'm pretty much out of spit here. The only other thought I've had is; do my Discovery injectors require to see a little more voltage than the Defenders ones in order to pulse earlier during cranking and in which case I am thinking of a way to splice into the injector wiring for each bank and connect to a remote 12V source and see if this makes a difference during cranking, but at this point I'm guessing..... keep you all posted. Again - I'm open to any good suggestions. One would have thought that with two patients open - ECU's exposed - one vehicle fires up immediately, one does not that we'd be able to figure this out by comparing and contrasting!!

 

My 95 D1 fires up almost to fast, I will be acquiring another 95 D1 at the end of this month so we'll see how it acts vs my Gold 95. I'm running Volvo 4 hole injectors, BMW/VW Fuel Pressure Regulator, and a 4.2L 14CUX ECU.

 

My 94 has Mustang 4 hole injectors, fuel pressure regulator looks original, and ECU too. Don't know the history of the fuel pump and have never measured fuel pressure, but have a new fuel filter. 155k miles (10k are mine). Took longer to start before I fixed it up (five years ago). Fires up faster after the first start of the day.

Looking forward to results from icatterm.

 

Here are latest measurement results including;
1) Power Probe 4 Fuel Injector measurements and comparison between reluctance to start Disco and perfectly starting Defender - interesting but no difference.
2)Some voltage comparisons with the Disco battery being jumped from my D2 - Some cranking voltages measured higher, no sure of significance - might repeat these again later in an attempt to get better confidence in the absence of a correlation to in starting quicker or not. (With all this playing around I've noticed that sometimes it's starts normally (quickly) other times not, so this failure mode is a little intermittent too - not helpful!)
3) Some random (what ever was easier to get to!) Fuel inj resistance measurements - Disco vs. Defender - no difference between vehicles, and all in spec. (16ohms)

Enjoy the numbers for reference, unfortunately they're not help me find 'root cause' to my reluctance start issue on the disco.

 

The longest period of troubleshooting time is finding out where the problem Is Not. Takes even longer if the problem is intermittent. Eventually you'll find where the problem Is, depending on the time budget.

At this point, we might try a new coil (especially if you don't already have a spare, or swap with the Defender). Maybe before that, check/compare fuel pressures.