2002 Disco not starting, have fuel and spark

**Giz11** · 22nd July 2018, 06:57 PM

I have an issue with my 2002 Discovery V8. The other day it started to missfire at idle but went away when the engine was reved. The misfire got progressively worse over the next few days and with some back firing on starting. After stopping at the shops it refused to start. It turns over ok . I towed it home and started to try to work out the issue. In repeatedly turning it over it seriously backfired to the point that it completely peeled open the muffler.
With the muffler now off, I changed the crankshaft position sensor, still wont start. I checked the fuel pump and that is working. There is only one code coming up on the Nanocom t "P1668 = Anti-theft Alarm Serial Link Fault Drive Cycle A, Occurred 8 times,Signal too low, Fault is not currently present, Fault determined as intermittent, Fault does not cause the MIL lamp activation" I can clear the code and the car still does not start. The code does not appear until I lock and unlock the car. I tested the spark on each cylinder via a timing light. No spark on 1,4,6. One spark at the end of the starting cycle when the key was turned back to position 2 on 3,5. Sparked 4 times then nothing on 2. Spark appeared ok on 7 and 8. I have checked the resistance on pins 32 and 46 at the ECU (connecting to the CPS) and that is fine it is same resistance at the sensor so the cabling should be good.
I have ordered new coil packs so will try them next but I am at a loss as to what may be the problem. Hope someone can help
Giz

**Pedro_The_Swift** · 22nd July 2018, 07:03 PM

Good call with the coil packs,, they usually let you know they are about to fail,,
If you worked in the same position as they do,, You'd be happy with 20 years service,,

**Giz11** · 23rd July 2018, 12:00 AM

Thanks Pedro,
The only thing is that having 2 coil packs fail at the same time would be rare. Anyway if its not the coil packs then I assume its the ECU.
Giz

**101RRS** · 23rd July 2018, 12:23 AM

A blown out muffler is normally caused by an intermittent or no ignition source. Cylinder is still getting fuel injected but due to no ignition it is passed into the exhaust and when the amount and mixture is right - bang. - ask me how I know

15062010.jpg

I think you are on the right track - these engine do have a bit of history with coil packs. So as you are doing - replace, if not check wiring and ECU ignition signal - then the only other thing would be cam sensor and crank sensor. There is not much else.

Garry

**ballbag** · 23rd July 2018, 11:24 AM

If tacho is working and showing sensible cranking revs (1000rpm?) then crank sensor can be assumed to be ok.

Alarm fault might be a red herring. Think immobiliser works by not supplying power to fuel pump. There is a schrader valve (I think) on fuel rail behind/below coil packs. Open valve while assistant cranks engine to check fuel pump operation.

Think cam senor controls injection sequence but ECM will revert to default if sensor fails so engine should still run.

Seems spark issue mostly relates to LHS (passenger) coil. Think coils are the likely culprit.

I soldered extentions into the coil signal wires and relocated packs to the firewall on my vehicle. Will never be traumatised by failed coils again.

**Roverlord off road spares** · 23rd July 2018, 11:29 AM

Originally Posted by ballbag

I soldered extentions into the coil signal wires and relocated packs to the firewall on my vehicle. Will never be traumatised by failed coils again.

Good idea, thought about that when i owned a v8 D2.
Do you have pics, and did you need to get non standard leads to use this?

**ballbag** · 23rd July 2018, 11:31 AM

Correction: immobiliser disables starter motor relay, not fuel pump. So alarm fault certainly unrelated.

**ballbag** · 23rd July 2018, 11:35 AM

No pics at hand sorry but from memory I cut and welded existing coil bracket and bolted it to an existing, unused threaded hole infront of the passenger.

Yes, I had leads made up by local auto parts joint. They were ready overnight and cost about the same as a standard set off the shelf.

**Giz11** · 23rd July 2018, 03:34 PM

Hi Ballbag,
The tacho does not move when cranking and that is with a new cps installed.
Could it be an earth fault at the ecu side ?
Regards
Giz

**ballbag** · 24th July 2018, 02:20 PM

Hmmm...

There are spacers for the crank sensor so the pickup is the correct distance from the flywheel. Did they go back in?

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