It's happened again

Just to up date you all, after the garage had my R/R for 3 weeks to sort out the starting fault, i have had it back less than a week and it's refused to start again this morning. :doh:

Got the wife out to turn the key while i played with the wiring loom and it started, so dorve to my workshop, it miss fired a couple of times on the way, turned in and engine cut, i pulled the loom around again and it started, so i managed to park it.

I decided to strip the loom out myself to find out which wire it is, by the time i got the coverings off with all the tape, it just will not even try to start, looks like i will have a busy weekend.

I found the repair the garage did :hysterically_laughi and for what they charged me for it, i am in the wrong job.

I dont know if this has anything to do with it but the gearbox electrical's are playing up, i had a breif gearbox fault message and then nothing, but the gear position idicator on the dash isn't there, does the box default to 3rd or 4th gear, as it still drove but sluggish away from the lights, turn off the ignition and restarted back to normal :wtf:

Will let you know when sorted.

That is the box defaulting because of an issue. The instrument cluster will display gearbox fault even if the battery is a bit low on cranking but with the running issue and the light missing then it really is logging faults.
What loom was causing the issue?

hi Mtechuk
It only displayed the gearbox fault for a second or so and never came back on, but the P-R-N-D-3-2-1 was not displayed either, the only way i got the display back was to turn the engine off and restart and all seem to be working as it is supposed too, with the full use of gears.

I changed the battery the last time it stopped starting, this new one spins it over a lot, lot faster than the one i took out.

Is it still not starting. What loom was causing the issue?

Mechuk
It was the crankshaft position sensor wire, somwhere from the plug to the ECU, so ripped it out and replaced it, the old one was brittle, i think it due to the heat from the exhaust and engine.

Ian

Has it started since you replaced the crankshaft wire? Do you know about the shield wire?
You can get a lot of interference on the crank signal if it is not shielded correctly. The TD5’s are terrible for it. The signal is weakened with interference from a worn starter motor.
I know, it sounds crazy, but had 3 of them know. I couldn’t believe it myself. I put a big piece of foil matting between the starter and crank sensor and started every time, removed it and wouldn’t start.
I am not saying P38’s have the same issue, just mentioning the importance of the shield wire and the fact that it has to be properly grounded.

Hi Mtechuk
I did a temporary connection and it fired straight up.

The starter motor is on the other side of the engine on the v8's.

I then made proper connections and taped the wires back up, i rerouted the cable away from the cat, the wire i used was a twin pair screened, there were two wires twisted, with a screen around them and another two wires twisted and screened, so it would be classed as double screened i suppose, i used the pairs as single cables, been running great so far, once i got it running again i realy pulled all the wires around to get it to stop, but there was not even a misfire.
Ian

That’s good news. I was just using the starter motor as example of how interference can cause problems. The starter issue was on a TD5
With poor earth bonding it can be caused by the wiper motor, alternator, Ht, leaking coils, bad plug leads ect.
Glad you got it sorted