Hello all,

Recently I took my car in for diagnostics because after some reading around I was certain I had injector issues. Turns out I was right and that one injector is over-fuelling and another under-fuelling. I am assuming these will need replacing, or at least refurbishing. However, should I consider the fuel injector rail as a cause? From what I can tell few things have been replaced on the car since new, so it is probably the original loom. Can the loom itself cause over/under fuelling or is it definitely the injectors?

I plan to buy two injectors and get them refurbished, then swap with the faulty ones, and keep one as a spare for future problems. I'm a bit confused re: coding, some say that's not an issue, others say they need to be. Does anyone have any pro-tips on how to increase the chances of them coming out with little to no pain? At the moment I am running BP Ultimate and every tank I'm using Comma Diesel Magic.

When I asked about the cause of the problems he suggested that water in the fuel system could have caused it and therefore both the diesel filter (fair enough, it needs changing anyway) and low-pressure fuel pump should also be replaced. What are your thoughts on this? For this he quoted me £480, which seems expensive. So I'll get the parts and try and get that done myself after New Year. On the subject of pumps, what are people's opinions on brands? I gather the cheaper models are noisier but is there a performance issue as well which means I should go for Pieburg? Filter-wise, I assume original is better than saving a few pounds on after-market. In terms of difficulty, and potential risk - is changing the filter/LP pump something you'd recommend for someone new-ish to looking under the bonnet?

Interestingly the problems only manifested themselves when I ran some Comma Diesel Magic through the car, and I've been only using BP Ultimate since I bought it, so I imagine the injectors lost some of the gunk covering them and that's when the problems started.

Lastly, I'm so pleased I took my car in for diagnostics. £60 well-spent IMO.

Walk away he is trying to have you over, the injector that is over fuelling is the one that need changing the other one would most likely be trying to compensate for that. have you done a leak back test if not do one to make sure, is your low pressure fuel pump making a noise if not why are you changing it, if you change yes go for a pierburg only.

To remove the injector easy first make sure the engine is hot then the injector should just pry out with no effort, be careful prying it out use a metal flat bar across the cam cover or it can get damaged.

The injector rail is 'common' to all injectors - can't see how it would over fuel 1 injector whilst under fueling another.

Could the Comma diesel magic not have dislodged muck from the system that has got trapped in the injectors? Maybe blocking 1 while keeping another open?

£480 is a lot more than it should be.
Takes less than an hour to change filter and pump yourself.
£150 for pump and filter...

GrumpyGel said:

The injector rail is 'common' to all injectors - can't see how it would over fuel 1 injector whilst under fueling another.

Could the Comma diesel magic not have dislodged muck from the system that has got trapped in the injectors? Maybe blocking 1 while keeping another open?

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Apologies, I think I meant the wiring loom. I'm still learning!

I do suspect the cleaner has dislodged stuff, I'm continuing to run premium diesel and cleaner through until I get to a workshop and get them out.

pardec said:

£480 is a lot more than it should be.
Takes less than an hour to change filter and pump yourself.
£150 for pump and filter...

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Yeah, he was clearly either not keen to do the job or just felt he could charge a premium because he's a Land Rover 'specialist'. He's the second guy I've been to locally and have left unimpressed. The only reason I went this time was for the diagnostics, but yeah - I'm going to get the parts and do it myself.

Arctic2 said:

Walk away he is trying to have you over, the injector that is over fuelling is the one that need changing the other one would most likely be trying to compensate for that. have you done a leak back test if not do one to make sure, is your low pressure fuel pump making a noise if not why are you changing it, if you change yes go for a pierburg only.

To remove the injector easy first make sure the engine is hot then the injector should just pry out with no effort, be careful prying it out use a metal flat bar across the cam cover or it can get damaged.

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Thanks for your reply, I've not done that test - currently looking for an idiot-proof method. I think it's injector #1 that is overfilling (or at least the left-hand one as you look at the engine) because there is a build-up of diesel around that one, I cleaned all around there when I did the inline stat mod and it's gotten mucky rather quickly.

Nope, the pump isn't making a noise however he said that he suspected water in the system was the culprit of the issues. Now, as I'm a novice I took his word at face value, but it seems maybe he's just after changing things for no reason?

Thanks for the advice re: the injectors. That's going to be a priority for me once the hassle of Christmas is over.

TSR2 said:

I've not done that test - currently looking for an idiot-proof method.

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You can buy a spill/ leak off test kit off EBay for very reasonable amount. You can find loads of videos on YouTube on how to check diesel injector spill/leak off testing.

TSR2 said:

I think it's injector #1 that is overfilling (or at least the left-hand one as you look at the engine

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Yes, that's No 1.

TSR2 said:

because there is a build-up of diesel around that one,

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If it's getting diesel building up around the injector, then you have a leak somewhere. It'll be the copper washer which seals the injector to the head. Or the rail to injector transfer pipe. Or the spill pipe T piece, or the spill pipe it's self.

TSR2 said:

Nope, the pump isn't making a noise however he said that he suspected water in the system was the culprit of the issues.

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Start by draining the sedimentor/ water trap, and see what comes out. If lots of muck and water comes out, then replace the fuel filter with a quality replacement.