Rover 25 sounds like a Transit - read on...

[MeldrewsMate]

A few days ago my Rover 25 turbo diesel ie model developed a classic diesel knock, like a transit van going up a steep hill. It's a 2001 model with the Rover L series 2 litre lump. It's diagnosis has proved elusive so far, so I'd like to ask the learned and experienced here for help. Actions so far...

1. Removed and checked EGR valve, no sign of excessive sooting, and the vacuum capsule is intact.
2. Ran with EGR suction pipe OFF - no change
3. Ran with EGR pipe direct to the vacuum source - no change.
4. Disconnected the MAF sensor, reconnected the MAF sensor - no change!
5. Checked the coil resistance in no.1 injector (but not the continuity back to the ECU yet) - no change whether connected to the loom or not.

The symptoms are:-
Loss of power
Excessive clattering at low engine speeds and throttle, seeming to quieten down above 2000 rpm and wider throttle openings...this is not conclusive as I'm not taking it over 2500 rpm as a precaution.
Higher fuel consumption, in the order of 20% thirstier.
Very occasionally, and without pattern, it has suddenly gone quiet, and much more power has become available...but this won't last longer than a couple of seconds.

I look forward to any useful ideas, and to being able to drive without the ear defenders. It has been suggested that a coil in the fuel pump has failed, and the very early injection of the fuel is causing the loud knocking noise? I have no experience of this, but welcome suggestions for testing it before splashing out several hundred pounds for a new one

Any ideas? I have a multimeter and hand tools for testing.

MM

 

[Belle427]

your probably in the right area with the incorrect injection time or over injection possibly due to a duff injector, does the engine have a timing belt?

 

[Peter.N.]

If its knocking on all cylinders I would also suggest over advanced pump timing, but unless its been interfered with that is unlikely to happen as any belt slippage would ****** it. Its possible that something in the fuel pump has failed, but again, that will usually result in retarded ignition. If its only knocking on one cylinder a faulty injector would probably be the answer - a strange one.

 

[wotan]

If you are talking single rail injection, and the disconection of the MAF sensor along with No 1 injection coil, then the problem I would think will be the ECU, or possibly the lambda sensor.

Wotan

 

[Peter.N.]

Ah, didn't realise it was a common rail engine.

 

[MeldrewsMate]

It turned out to be the diesel injection pump, a failed timing solenoid inside it.
Seemingly the injection pump is set to give 30deg of advance, the electronics ******* the injection timing via this solenoid.
I diagnosed it by retarding the timing by one tooth of the pump timing belt; from memory (as it was a very long time ago) each tooth moved changes the timing by 20 degrees, so I ended up with fixed injection timing of 10 degrees advanced. The result was a much quieter car with more power, and something like normal fuel consumption, of course the ECU would not let the engine rev more than 3800rpm, but that's plenty enough to pass the MOT, and much higher than the 3000rpm limit imposed by my right foot.

Posting this 18 months later, as it's still relevant to others with a similar problem.