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Injector Life and Smoke.

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Bought a new beast on the weekend that is smoking quite a bit under almost any load. 

At Idle it's clear as but once you start to feed in some power it's very black. 
The previous (one) owner said it needed The injectors doing and when questioned said they were last done 3 and a half years ago.  That seems a short life to me and I don't think the thing has been driven a million miles in that time. 

He said he hadn't touched the fuel or the turbo as he was a non mechanical person but I'm wondering if the injectors are the likely cause of the plentiful smoke or maybe it's just a fuelling issue? 
​The thing starts at the first look of the key even without the GP's when cold and idles and runs beautifully.

This is a 4.2 with an after market Schwitzer turbo. Would there be any difference in the way the injectors are set up with my NA 4.2?
It seems like an over fuelling issue to me but if it is the injectors, I could swap them over with the ones in the old beast which as far as I can tell are fine. 

What's the best path of Diagnosis?
Swap injectors or try turning the fuelling down first?

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Injector can get wrecked easily by dirty fuel, having said that if it has done in excess of 100 K in years it could easily be that.

Another thing black smoke under load is always over-fueling issue. If it has aftermarket turbo this could be a problem as who knows how the mapping of the turbo syncs with the mapping of injection pump.

I'd check if the smoke compensator has not been wound up. Its common apparently. Also I'd checked just in case the diaphragm is broken or and boost pipe to it (compensator) has a leak/crack.

It could easily be just that.


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Yes. The owner said he had the Turbo put on 6 months after he got the ( Then new) truck. 

It's not just smoking on spool up, it's smoking under load as well.  I'll keep a look out for a compensated pump as these really do work best for tuning.  The wifes car has on on it and the thing is great to tune. 


It's not really the smoke per se that concerns me. 
I want to put this one on Veg as well and smoke means unburnt fuel which with veg will lead to gumming up the rings. I need a pretty clean burn to make sure that doesn't happen. 
I'm going to fit a water injection system and run 5% ULP which will help offset any gumming issues but best to make sure the root problem is addresed and not just worry about the band aids. 

I might try tuning the fuel screw this afternoon if I get a chance and see what happens.

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