- Thread starter ukracer
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Onoff
In the land of the unfinished project I am King!
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I just replaced one on the wife's Pug 206. Weird fault. Only running on 3 cylinders. Plug No.4 was wet. Spark coming off the coil pack. IR thermometer on the exhaust manifold showed No.4 running about 100degF cooler than 1,2 or 3.
Replaced the injector on No.4 with a new one, same Magneti Marelli type as original.
All back up up and running a treat.
Replaced the injector on No.4 with a new one, same Magneti Marelli type as original.
All back up up and running a treat.
8ob
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You can do an on the car leak back test with calibrated pots, they are cheap and easy to use.
Bob
Gareth_16V
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Sounds like operating the starter motor and the ECU at the same time might be too much for the battery, or too much voltage drop whilst cranking?
Munkul
Jack of some trades, Master of none
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yeah this, or something else electronically related. How could it possibly be an injector fault? They clearly all work fine if it bump-starts.
Moose McAlpine
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I'd be looking at something like faulty rail pressure sensor (or dying pump) Not uncommon on older diesel Mercs, they stop reading at the low end of the scale (cranking is only ~200rpm) and the injectors won't fire without the ECU seeing sufficient pressure.
Of course, it needs to be diag'd with live data, but i wouldn't be looking at injectors first.
Trevorleach
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Actually quite a common fault on common rail diesels, one injector leaks off to much fuel so rail pressure cannot reach what is needed to start the car, normally 200/300 bar, so a bump start or easy start to get the engine turning fast enough gets the rail pressure high enough for it to run.
I am coming the conclusion the injectors on any cr diesel with over 100k on the clock are running on borrowed time.
Munkul
Jack of some trades, Master of none
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Fair enough, learn something new every day
My experience with CR injectors has mostly been VWs which start throwing up codes and faults when the leak off rate exceeds a small amount. Some injectors in some engines seem worse than others, regardless of injector manufacturer...
If the engine runs smooth once started, a leak-off test with measurement tubes doesn't usually show any issues.
I usually just disconnect the leak-off pipes, clamp the return (may need to plug the individual connectors if it's all hard lines), wrap a bit blue roll around each injector, and get somebody to crank the engine over while watching. If there are any sticky injectors, it's usually pretty obvious.
Ideally you'd do a live data check first, just to make sure lack of fuel pressure is the only issue.
I usually just disconnect the leak-off pipes, clamp the return (may need to plug the individual connectors if it's all hard lines), wrap a bit blue roll around each injector, and get somebody to crank the engine over while watching. If there are any sticky injectors, it's usually pretty obvious.
Ideally you'd do a live data check first, just to make sure lack of fuel pressure is the only issue.
