Just finished putting the car back together rather replacing the head gaskets, fired it up and left it to run a while to get the coolant drawn through.

I'm pretty sure there's a miss fire as it's running a little lumpy but it smooths out a little when it warms up. When blipping the throttle the revs seem to cough/dip before rising.

After a while a good amount of smoke started rising from the back of the engine bay.

Looked underneath and found this:

Got the fire extinguisher out and cooled it down and the smoke eventually stopped.

Would a miss fire cause the cat to get hot enough to almost set fire to the heatshielding on the floor? I'm thinking the unburnt fuel from the miss fire is being pumped in to the cat where it's burning off.

What's weird is that the cat itself wasn't glowing and the red patch is only at the rear of the cat rather alongside the whole cat.

When it had cooled a bit I reached down to the coil and made sure all the leads were attached, they seemed ok but one or two did move in a little. I then checked the leads to the plugs and they seemed ok too.

I then started the engine up but I'm not sure if it sounded better or not. I didn't let it run long.

Pulled the spark plugs out (passenger side) and looked at them. I'm not sure of the cylinder numbers but I think that side is 1, 3, 5 and 7? 1 and 7 were a nice grey-ish colour and 3 and 5 were black.

Possible miss fires on 3 and 5 that cleared up with the leads/plug check and the excess fuel then burnt off and turned them black on the second start up?

Or, any other ideas? Kind of reluctant to start it up again until I get the fire extinguisher refilled!

3 and 5 plug leads reversed? Easily done as they are next to each other.

Each plug lead is only long enough to reach the plug it's attached to. I didn't remove them from the coils when I took those off so they've not been crossed over at that end either.

There's no warnings lights on the dashboard - are there any diagnostic software tools that would identify if/where the miss fire is?

I imagine a Nanocom would but I don't have one, the prices keep going up and up and I imagine it would take a fair while to get here from Cyprus.

Any generic OBD code reader should tell you which cylinder is misfiring with a P030x code, although you might be unlucky and just get P0300 which means multiple misfires. The price of the Nanocom keeps going up as it's priced in Euros. When I got mine the pound was worth almost 1.5 Euros, now it's down to 1.08.....

I have a generic Bluetooth OBD2 reader bit it won't connect to the P38. Works fine on my girlfriend's Astra though :(

I'll have to try it again and check the OBD2 port - it could have damaged pins or something.

I had exactly the same on a car, it turned out that one of the coil leads ( supply) wasn’t on properly, check both the connectors and all plug leads

Isn't there something on the Thor engine where there's a plug for the coils and another plug that should go somewhere else that can be interchanged? Have you connected everything up right?

[Gilbertd](/user/GilberGilbertd wrote:**

Isn't there something on the Thor engine where there's a plug for the coils and another plug that should go somewhere else that can be interchanged?

I don't know. There were two plugs for the coils and they were both connected. There didn't seem to be anything else in that area.

[Gilbertd](/user/GilberGilbertd wrote:**

Have you connected everything up right?

I'm pretty sure I did. As far as I could tell each plug could only go in one place based on the shape of the connector. And I didn't see any plugs left disconnected.

The wiring you can’t get wrong, unless you’ve swapped idle valve with coil, but there different colours if I remember correctly, it does sound like a lead mix up or plug in the wrong place or come off

The two plugs that went in the to coils were black IIRC.

So the idle valve uses the same shape plug but a different colour? Is that the piece attached to the top of the inlet manifold with two large P Clips? I'll check that when I get home.

Idle seemed to be ok though, besides the miss fire. It settled and slowed when the engine warmed up etc.

I'd seriously consider replacing what remains of your heat shields too.... lucky not to have had a proper fire with the state they're in. Well done for having the extinguisher though.

But yes, the idle valve/motor thing has the same shape connector as the coil pack stupidly.

Sloth wrote:

I'd seriously consider replacing what remains of your heat shields too.... lucky not to have had a proper fire with the state they're in. Well done for having the extinguisher though.

But yes, the idle valve/motor thing has the same shape connector as the coil pack stupidly.

I'll be honest, it wasn't my extinguisher. It belonged to my girlfriends dad who luckily lives next door and was helping me out!

I'm definitely purchasing one of my own though.

I did think about replacing them after seeing what had happened. Not looked in to it yet though.

Well at least there was one to hand :) The fact the heat shield got that hot without the cat even glowing says they're done - it actually looks more like its burning given the ember line.

I've replaced mine with dimpled ali sheet - although you can still buy new OEM replacements. To fit those though would ideally need the exhaust dropped out. Molesting the ali sheet into place once cut with the engine out and Y pipe hanging free was painful enough.

Yeah, I think it was very close to a full on fire. The ember line was glowing/pulsing like wood on a fire!

And now I can't find the key for the damn thing to go and check the wiring :(

Were there different engine wiring looms for different model years/spec levels etc?

A guy from my Land Rover club has given me a full upper and lower Thor intake manifold assembly including fuel rail, injectors and engine loom for me to swap bits out with if I rule out the simple stuff. Some of the connections seem to be in different places though.

In my car the throttle body connector and the connector for the piece below the idle valve are on their own spur that comes out of the loom near the connector for the idle valve:

On the loom I've borrowed they go through loom with the injectors:

Are there any other differences that would stop me being able to make use of this other loom if I need it?

If the inlet is different then it’s a gems , all the Thor are the same, I don’t think you’ve got a problem other than a crossed wire or lead mixed.
As mentioned before I had exactly the same, threw me a bit to be honest, was happy to find loose connector on coil pack, mine was left hand side, and left hand connector ( on the right facing engine bay, passenger side )
At least it’s not to bad getting a Thor apart, much easier than a gems, 10 minutes and your be at coil packs ect,
Remember when facing the engine, rh bank is odd, lh bank even.

Yeah, he's just given me this stuff as a last resort in case it's not something really simple.

His kit is a 1999 Thor and mine is a 2001 Thor. His manifold is the bunch of bananas as well.

Fired it up today and there's no trace of a miss fire whatsoever. Which I guess is good?

It has sprung a leak from the top hose though, right where the pipe that goes to the engine joins the plastic T piece. I'll try replacing the spring clip with a jubilee clip and see if that helps.

Once that's done I just need to sort the LPG....it's beeping at me every few seconds

Ok, so the leak is from the T piece itself - the plastic is old and soft and the bit going to the thermostat simply snapped off as I tried to undo it!

Now buying a new top hose - does anyone know if anyone makes a metal T piece for this?