760 V6 getting closer to scrapyard...help!

[russwinchester]

Yep, coil made no difference, not surprising though!

Any idea what this is and where it goes? It was loose when I got the car.

[Laird Scooby]

Originally Posted by russwinchester

Yep, coil made no difference, not surprising though!

Any idea what this is and where it goes? It was loose when I got the car.

No wonder it won't start or run!

That's meant to be on #1 plug lead (rear left) and tells the ECU when #1 is firing and at what speed. Don't ask me why they fitted those as well as the CPS on top of the bell housing but the EZK ECU needs BOTH inputs to be able to fire the engine!

If you can slide the spark plug boot off #1 plug lead, you can slide the lead through the hole (if memory serves there's an orrow on it pointing towards the plug so double-check for this) then slide the boot back on. Some silicone lube may help the boot to slide off and on, if not then i may have a spare from my original set of leads to prove the point but i'd advise buying a new set of leads with the RPM sensor included.

https://www.rockauto.com/en/catalog/...plug+wire,7224

Only two choices of leads there with the sensor included, AC Delco for ~£73 and SPM (aka Intermotor) for ~£55, all plus S&H, currency commision etc so likely to nudge £80, maybe more.

See what you can do with the spark plug boot first!

[russwinchester]

Oh good god. I assume when you say rear left, that’s left of car not left as I’m looking at it from the front…

Because this lead (left of car nearest bulkhead) has been replaced with a generic one, it’s odd. Which explains why the sensor is hanging loose.

The only thing that niggles me is that the car was running on easy start before as the seller demo’d it to me, but I guess easy start could hide a multitude of issues.

Let me see what I can do…thanks so much for all the help!

[Laird Scooby]

Originally Posted by russwinchester

Oh good god. I assume when you say rear left, that’s left of car not left as I’m looking at it from the front…

Because this lead (left of car nearest bulkhead) has been replaced with a generic one, it’s odd. Which explains why the sensor is hanging loose.

The only thing that niggles me is that the car was running on easy start before as the seller demo’d it to me, but I guess easy start could hide a multitude of issues.

Let me see what I can do…thanks so much for all the help!

That's correct, the left of the car as viewed normally - you're back to front when viewing it from the front of the engine bay.

You will likely get a slightly mis-timed spark without the sensor working, enough to fire Easy Start but not support running on petrol.

The CPS gives a pulse once every revolution, the plug lead on #1 (or any other cylinder) will only give a pulse once every 2 revolutions which is why LH injection cars take a couple of turns to fire - they need the CPS and RPM signal to be at about the same point for the EZK to work out whre the firing order is, why they did it like that i've never worked out.

Chances are they fitted a generic lead because #1 lead failed but they didn't think the RPM sensor was important or couldn't work out how to fit it so left it loose and then couldn't work out why the replacement HT lead didn't get it going either.

I remember when i renewed the HT leads on mine, it wouldn't start at first - i realised i'd forgotten to plug the RPM sensor in!

When you try to get the plug boot off the lead, use a long-bladed screwdriver or similar in place of where the plug would fit and push down on the boot towards the end rather than trying to pull the lead out of the boot the other way as you may stretch it too far that way. Some silicone spray lube sshould help it slide easier too.

[russwinchester]

So, have managed to get the sensor in place but still no start. There was a bit of a flutter but so it did make a difference but it is intermittent. Sometimes the Rev counter kicks slightly, most of the time it doesn’t. Have also used a genuine bougicord lead and no difference. So back to the drawing board I guess. Wonder whether I have a faulty EZK module. Where is it in the car? I can’t put my hands on it…..again any help would be fantastic!

[360beast]

Remove the trim under the drivers part of the dashboard and you will see it screwed on to the brake pedal bracket, that's the EZK, the fuel ecu is in the kick trim in the drivers footwell.

[360beast]

I just thought, have you done a compression check? The V6 is more susceptible to headgasket problems than the red blocks, doing a compression test will atleast confirm if it has enough compression to fire.

[Laird Scooby]

How long did you keep the key turned to start (position 3) for and did you try opening the throttle gently?

Also you did the trick the other day of removing the plugs and trickling some oil or ATF into the bores - do that again now you've got more of a hope of it actually firing.

[Laird Scooby]

Originally Posted by 360beast

I just thought, have you done a compression check? The V6 is more susceptible to headgasket problems than the red blocks, doing a compression test will atleast confirm if it has enough compression to fire.

It may give a false negative Luke, hence the trick of the oil down the bores.

[penninepullman]

I note that you have checked, but not replaced, the rotor arm and distributor cap.
I cleaned these on one of my 760s (I have three of them) recently when it would not start after not being used much due to Covid.
Still no start, and after doing many of the 'Green book' checks still no start.
Fitted new distributor cap (rotor arm was fairly new), and hey presto! - it started.
I think the main reason for distributor cap failure was the very poor spring pressure of the carbon contact to the rotor arm.

I have purchased my distributor caps from Parts Monster, approx £34, and although their picture shows it as a black one, the items supplied have been reddish brown. They are usually in packing from either Skandix or Professional Parts.
Rotor Arms I have purchased from ebay.