960 coil on plugs

[Laird Scooby]

Is it firing on all 6 again yet or haven't you driven it very far yet?

[liamcafs]

Yes it has changed. Still lots of white smoke. But it wil idle quite nicely now doesnt sound like it missing. As soon as you touch tje accelerator though the revs drop off and it nearly stalls. It will rev but its clouds of white smoke.

Its not raining today so ill have another look at it.

Btw i cant take it for a run its sorned.

[Laird Scooby]

Is it white smoke or steam? It's possible it's sucked some oil into the combustion chamber (depending which valves weren't opening properly) and that's throwing out the white smoke. Actually you added oil to that pot during the compression test, didn't you? Probably that burning off, could take a while to clear as it's probably sitting in the downpipes and/or cat now.

If it's steam, it could simply be the engine is still too cold to get rid of the excess water content of the fuel or maybe a head gasket problem. More concerned about the fact the engine tends to die when you hit the loud pedal.

Probably a vacuum leak on the inlet side, a split between the MAF and throttle body, faulty MAF, blocked PCV or similar. Those are the common faults, there are loads more to choose from!

Worth giving those things a check then (depending how close and how tolerant your neighbours are) getting the revs up to 2-3000rpm for about 10 minutes or so to make sure the engine is properly hot (keep an eye on the temperature gauge to make sure it doesn't overheat!) and then let it idle. Hopefully by then it should idle nicely on all 6 and respond when you hit the loud pedal.

My gut feeling is that because it's been missing for quite a while, all kinds of strange things have happened with oil getting in the exhaust and so on. Give it that run for 10 minutes and hopefully that will be enough to clear things through.

[960kg]

I had the same 6 cylinder 2.5 engine in my 960.....had it for around 6yrs hence my id name.

The 2.5 has a lower back axle ratio and so has around the same acceleration as the 3 litre but of course it has to suffer somewhere and it was on Mways at high speed you could almost see the fuel gauge going down because of the higher revs.....revs = fuel.

This will tell all about the 960engine......
https://www.brickboard.com/FAQ/700-900/960_90Info.htm

These engines suffer from oil pressure supply to the cams and valve mechanism and tell you that by a clackety valve sound when getting into higher revs when flat out. The only way to get rid of the problem is to split the sump with the section above it and put in two O rings instead of just one that is in the groove for the oil supply to the head.

There are also two inlet manifold gaskets for these engines and the original Pink coloured one always tended to leak and so gave irregular idle trouble so they were changed to the Green coloured one which was the upgraded recommended replacement.

These models as std. have huge exhaust boxes and will hold condensation for ages until the engine has got to working temp. then it has to expel all the water hence probably the white steamy smoke hanging around.

When you did the compression test putting oil in the chamber as you did pushed the compression much higher than the others so maybe just sticky valves which is another problem with these engines....the valves can get stuck open and stop the engine even starting!

A misfire is quite difficult to determine with these 6 cylinders and one can go on driving for a while before it is noticed. Apparently the motors love being used on M ways so perhaps all the slow running because of the oodles of torque just bungs them up with carbon etc.

Before you get serious taking it apart i would wait until you can get it out on the road and give it a fair good run.....it will do it the world of good as they are superb engines.

[liamcafs]

Thank you 960kg for the link to the resource, I hadn't seen that one!

I have done a bit more today on the car.

The engine today passes a compression test with flying colours every time
Also it passed a leak down check with over 95% on all cylinders.
There's no water in the oil.
There's no oil in the water (at least I don't think)

I removed the plug from each injector whilst it was running to see whether
a) it made no difference
OR
b) the smoke stopped

Well the engine ran worse when I unplugged each injector and the smoke/steam stayed the same regardless of the unplugged injectors too.

Having saved the 960 from the scrappy the engine and gearbox is now destined for my 240. Bearing in mind I will be replacing pretty much everything on the control side of the engine (ECU, engine bay wiring, ignition module etc) I'm pretty close to being happy with mechanicals so I may not spend too much more time trying to get it to work properly in the 960. I have discovered the car had been run on LPG at some point, the injector wiring has been chopped about also, possibly may be a factor in the poor running.

[Laird Scooby]

Sounds like a win for the ATF idea then?

Glad it seems to be sorted although as mentioned elsewhere, you won't know 100% until it's installed in another car and you can give it a blat along the Black Mountain Pass for a bit of fun!

If it has had LPG previously fitted, the usual course of events is to cut into the -ve side of the injectors for the trigger signal for gas injection and/or the injector emulator to prevent the ECU throwing a fault of 6 dead injectors!
If it was a single point LPG system there would have been a mixer ring installed on the throttle body for the gas but would probably have had injector emulation as well.
If it was single point with a mixer ring, it's possible the hose from the MAF wasn't tightened back onto the throttle body - that could cause the dying/fluffing as the throttle is opened. If was it gas injection, there will be injector "spuds" screwed into the inlet manifold near the injectors, if they haven't been blocked off they could be leaking air in, again with the fluffing/dying as a result.

On a different note, you probably won't need the cat on your 240 as it will only have to meet the emissions for the age of the car. That's a bonus but i'd suggest keeping the Lambda sensors (and renewing them too) for the mixture control.

[liamcafs]

Just been to have another look at the engine. It was gas injection i think, each of the inlet runners has a piece of rubber hose leading into a threaded stud in the inlet runner. These are only blocked off with an M5 hex head bolt jammed into the pipe!!

I won't be using the CAT but I will renew the O2 sensor.

Thanks for the help everyone, really appreciate it!!!

[Laird Scooby]

You should be able to unscrew those "spuds" from the inlet runners and blank them off with either M5 or M6 blanking plugs. Here's some M5 :

https://www.ebay.co.uk/itm/Nickel-Pl...3x-1QkXD87qYVg

A more cost effective option is grub screws and secure them with some Threadlock so they don't work loose :

https://www.ebay.co.uk/itm/M3-M4-M5-...M-r64sIC68_lYg

Most spuds have a hex on the outside for a spanner/socket to fit/remove them, others have a hex insert for Allen keys.

[classicswede]

DO NOT USE GRUB SCREWS!!!!!

Should they work loss bye bye engine

M6 bolts or cap screws will be best or weld up the holes better still.

Have they drilled into teh lower portion of teh manifold of the upper portion? I should have a spare manifold about if you are wanting to replace

[Laird Scooby]

[QUOTE=classicswede;2379359]DO NOT USE GRUB SCREWS!!!!!

Should they work loss bye bye engine

Originally Posted by Laird Scooby

A more cost effective option is grub screws and secure them with some Threadlock so they don't work loose :

My point exactly when i posted this. Proper blanking caps are available as already mentioned but they are £OUCH, cap screws would be an alternative with a suitable "O" ring on and again, a drop of Threadlock to prevent them working loose and causing vacuum leaks.

Alternatively, taper threaded grub screws so the tighter they are put in, the tighter they seal/grip, again with a drop of threadlock to help seal the threads but again, they start to get pricey.

It also depends whether they have drilled completely through the manifold runner or a pilot hole of say 4mm to let the gas through then the tapping hole of 5mm or thereabouts for an M6 thread so the hole is stepped. If so, grub screws with Threadlock will be fine.