Rebuilding the injector harness is not hard and there is a lot of written about it here an the forum and off the forum, this gives you the opportunity not only build it with better materials but also move the wiring out of the V. Run it over the inlet manifolds or around the motor but if its out of the V and you use high temp wire the wiring will never give you trouble again. I realise yours is a 95 and this is from older car but it will give an idea at least.
FI Harness Rebuild
Good Luck

 

So ... I spent most of this winter/spring re-wiring and was very happy to find that thecar started right up once I was done, however, I still have dense white smoke coming out of the B Bank. :-(

Back to square one. I will need to definitively figure out what the problem is. Here's what I know. B Bank has spark and when I disconnect the injectors the smoke stops. I guess I will start by checking the wiring, but is it possible the problem is in the amp or somewhere else? After that I think I will have to finally address whether or not I have a head gasket leak. I suppose the best way to do that is by compression test. I am very nervous about the outcome. A blown head gasket will be major $$$$$$$$.

 

I'd say you have a head gasket leak. With no fuel, you have no combustion and therefore, can't burn coolant. It's easy to diagnose a symptom as one problem, but you MUST look at all the symptoms, not latch on to one. Any engine misfiring on a whole bank will be very obvious by the unburnt fuel (it will smell and probably burn your eyes). As you don't seem to have that, we can ignore it.
When running without injectors, at least one of the spark plugs should've collected some coolant, you may even crank the engine with plugs out and observe a mist of coolant from a particular cylinder.
If the engine was hesitating on cranking, a cylinder or two probably was close to hydraulic lock, so you should be able to find coolant.

 

From the symptoms you describe I do not believe you have a head gasket failure. The white 'smoke' may actually be unburned fuel vapour, as it stops when the injectors are disconnected. It is likely that at least one, maybe more injectors are jamming open. Have you had the injectors cleaned and tested? Also are the plugs, or some of them, wet with fuel?

Maybe it would be worthwhile disconnecting the injectors one at a time to try and find out which one(s) are the problem? Also you could swap over the wiring A bank to B and vice versa, to see if the problem transfers itself to the other bank. If it does not, it is not the wiring, if it does, it is. Of course anything is possible, but if the coolant is not dropping down and fast, and no coolant is in the oil, a head gasket is less likely. Good luck anyway.

Greg

 

The V12 must be a very special engine, every other petrol powered internal combustion engine produces black smoke when overfuelled. White smoke is coolant or oil.

 

I quite agree. But in the case of the V12 HE, when overfuelled by stuck-open injectors the fuel does not ignite at all and the high compression followed by immediate decompression in the exhaust just blasts atomised fuel droplets unburnt out of the exhaust. Hence the white 'smoke' which is actually atomised unburnt fuel.

years ago I had personal experience of this and like you, I thought it must be a head gasket, but my garage specialist found otherwise. Obviously it could be a head gasket, but as the 'smoke' stops when the injectors are disconnected, I suspect not. Anyway, the tests I suggested the OP does will nail it. Sensible to do them before tearing the motor apart!

Greg

 

The more I read all the threads on this forum, the more I am impressed by all the posters. The knowledge of most people here is incredible. Thanks again guys...

 

Before you get too far involved and decided to take drastic measures as pulling down the motor, try and save yourself a little time and hassle with just a little more effort.
Questions?
1, Are you loosing water/coolant?
2, Is there Water/coolant in the engine oil?
3, Have done a compression test?
If you can answer yes to either of, or both of the first two the third should tell you where the problem lies. If No on the first two you can do the third as confirmation test. If its all good I wouldn't even look at pulling that motor down.
Start with injectors and ignition issues and go from there.

 

I am not a mechanic, but will throw my 2 cents in.

I suffered the dreadful Marelli rotor failure. After applying the fix as prescribed by Kirby Palm, copious amounts of white "smoke" blew out from the passenger side exhaust for a minute or so. Unburnt fuel can definitely look like this.

No further problems.