Dangerous injector testing idea?

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heath robinson
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Dangerous injector testing idea?

Post by heath robinson »

At 37 mpg (xantia td 95) and black diesel smoke in headlights behind even from gentle pre turbo set off, it’s looking like injectors. However, the last thing I want to do is spend a fortune getting them reconditioned to find it is something else, such as the pump. Having found some info on injector patterns on the net, would it be crazy to take the injectors out, re mount them on the end of the pipes and, from a safe distance, watch the spray pattern as the engine is cranked on the starter?
As an indication of my driving impact on mpg, I was getting 46 from a zx non turbo, which made it to 215k on original injectors and kept getting through smoke tests. Why do some injectors pack up prior to others?
I have also tried 2 lots of injector cleaner; neither use nor ornament is my conclusion. also checked air intake pipes as suggested.
Very grateful for any thoughts
tomsheppard
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Post by tomsheppard »

First change the following in this order.
air filter, fuel filter, oil filter and oil.
Be aware that Diesels often look worse in headlamps.
Get a friend to follow you in daylight.
37 is not that bad for a Xantia, the steps outlined should take that back to 41 or 42 which at this time of year is ok.
dnsey
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Post by dnsey »

If you do decide to watch the spray pattern, wear gloves and eye protection, and point the injector into a jam jar or similar. You should still be able to see (and hear) the injector working.
heath robinson
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Post by heath robinson »

thanks for the pointers. sadly i think it is beyond service items as the smoke and economy have been long standing and through services. thankfully the car does not burn engine oil, to this extent surely the state of engine oil will make no difference to combustion emissions as the systems are separate?
regards
bikeboyz
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Post by bikeboyz »

Injector overhall service is £25+vat per injector at LSUK. In headlamps you will see "smoke" which are particulates, you wont see them in daylight. Thick black smoke in day light will be overfueling, either too much fuel, or not enough air or both.
heath robinson
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Post by heath robinson »

like the jam jar idea…hadn’t even crossed my mind....that would introduce additional safety. I have no idea of the force, presumably a jam jar would not be blown to pieces? Do you think I would be able to spot a poor spray pattern or is the process too fast?
Thanks again
tomsheppard
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Post by tomsheppard »

Oil thins due to combustion by-products, causing more to get past the rings.
heath robinson
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Post by heath robinson »

fair point... thanks
paranoid
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Post by paranoid »

I Agree with tom, looks 100 times worse at night than it really is, got my mate to drive mine while I followed and he aint a sympathetic driver, was a bit smokey but not to bad.
Dave Burns
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Post by Dave Burns »

You would be wasting your time and taking risks with both your person and the injection equipment, the other equally important factor is the opening pressure of the injector, this you can't test for even if you know what to look for in the spray pattern, injectors that open too early because of lower opening pressure will balls the timing up, find a good specialist.
Dave
Dave Bamber
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Post by Dave Bamber »

Please don't mess with injectors, they are not a DIY job other than taking out and screwing back in. If you get your hand in the way of the spray, the fuel can pass through your skin and the results can be fatal. Take the advise from Dave Burns, find a good specialist.
macs
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Post by macs »

Messing around with altering or adjusting the spray patern of an injector is a waste of time and could be dangerous, as has already been said. Black smoke is over fueling which could be caused by (1) a blocked/dirty air filter or (2) interference with the governor adjuster screw or (3)interference with the maximum speed screw. All easy to check! Start with checking the filter; if OK screw in the governor adjuster a little at a time (turn it 1/8 of a turn, tighten the lock nut and check for smoke by revving)Clockwise reduces the amount of fuel. Can also reduce power. Make a note of the position of the screw before you start, as a reference and also to go back to where you started. The governor screw is at the back of the injection pump, and may be sealed. Another reason for smoking is an over advanced/retarded pump, but this generally produces grey smaoke. Timing a diesel engine is not easy without the right equipement. Good luck!!!
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Post by Wookey »

I think you're all being a bit paranoid about injector-fettling here. Obviously you need to take care not to do anything dumb, but that applies to plenty of other items when car-fettling. It's true that in this case there probably isn't much point just looking at them, as only gross problems are likely to be visible and what you mostly want to check is opening pressure.
Nevertheless, as veg-oil people will tell you, injector fettling is not rocket-science - you just take the body to bits and adjust the shim to adjust opening pressure. And you can get different nozzles to produce different spray patterns, which can be a whorthwhile upgrade if using veg-oil.
Mosser
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Post by Mosser »

What you need is one of these !!
http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... 98063&rd=1
Alternatively, could you not just rig up your own pressure gauge and some sort of high pressure pump to test them ?, i dint know what sort of pressure is needed to open a diesel injector, but my bike pump can produce 300psi
oilyspanner
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Post by oilyspanner »

Diesel specialists have a device called a pop tester which allows you to see the spray pattern behind some thick glass, I think they look for a fan shaped spray and no dribbling.
Stewart
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