Tuscan mis-fire
Tuscan mis-fire
Author
Discussion

ahehir

Original Poster:

7 posts

254 months

Friday 18th June 2004
quotequote all
Can anyone advise.....? I have recently bought a Tuscan (about 2months ownership now) despite a few little glitches it has been 100% and I use it everyday....!

I am afraid it lives a fairly tough existence, as its summer home is outside my house. But I follow the warm up procedure each time I use it and it has been fine. However when it rains it develops a misfire, like its running on 5 cylinders, this morning it also started popping loudly from the exhaust which I assume was unburn't fuel from a cylinder not firing???? but thats a guess....

Has anyone else had a similar problem and have they found a cure...? I am puzzled because I assume it is because water is getting into the LT or HT circuit but as this happens when the car is stationary (i.e. I didn't drive the car in the rain) I find it difficult to understand where the water is coming from unless it is running off the bonnet somewhere?

Help... its starting to annoy me.....

andyvdg

1,537 posts

299 months

Friday 18th June 2004
quotequote all
Sounds like an old problem. The plugs are sealed - water can run down and get onto the engine. It sounds like one of them isn't sealed properly so when it rains you get the misfire. Dealer fix or yourself if you're handy under the bonnet.

Cheers,

Andy.

ahehir

Original Poster:

7 posts

254 months

Friday 18th June 2004
quotequote all
cheers andy, do I need to get new plug then? do you know is the seal part of the plug or a seperate bit..... thanks again.

andyvdg

1,537 posts

299 months

Friday 18th June 2004
quotequote all
Don't know any more - it's a TVR so I would guess squishy bathroom sealant!

Cheers,

Andy.

john a

196 posts

288 months

Friday 18th June 2004
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I "think" the seal referred to here is actually the sealing of the rocker cover. That is what should keep the plug recesses dry. If one of the recesses gets water in it it causes arcing from the top of the plug, via the puddle, to the cylinder head. There won't be water actually in the engine - unless you have a much bigger problem.

You will need to replace the plug if it is a frequent problem. It will be b*ggered and sooty black.

John.

TSS

1,134 posts

284 months

Friday 18th June 2004
quotequote all
The early Tuscans had a problem with water running straight off the windscreen onto the sparkplug cover on the engine and getting onto the plugs. On the newer ones they redesigned the piece of fibreglass below the windscreen under the bonnet so it channelled water away from the cover. (You will probably have to remove the bonnet to see what I mean).

I have helped a TVR mechanic reseal the plugs on my car. The plugs are all sealed in by their cover. What you need to do is:

Remove the bonnet and remove the sparkplug cover which is the flat piece of metal on top of the engine with a Speed Six logo on it. It just unbolts.

Check for any moisture under there and in the plug recesses and dry out if necessary.

Remove any old sealant on the cover plate by scraping it off with a Stanley knife or similar.

Run a bead of sealant* all the way round the edge of the cover plate and bolt it back into place. At the top edge there are 2 larger apertures which will require a bit more sealant to be pumped in once the cover is bolted down to create a complete seal.

Leave the sealant to dry and that should prevent any more water getting in.

* TVR use some sort of black sealant which looks silicon based. I would call a dealer to find out exactly what sort they use.


This all assumes that water in the sparkplugs is the problem. It’s less likely that water is getting onto the coil as that is fairly well hidden away below the airbox (the big black box on the offside of the engine) and the HT leads are routed around the back of the engine to it.

ahehir

Original Poster:

7 posts

254 months

Friday 18th June 2004
quotequote all
Thanks everyone... looks like I'll be getting the tool kit out this weekend.....!