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406 hdi 90hp fuel problem

Only doing 31mpg on long runs. Noisy tappetty sound from engine between

2K - 3K revs then disappears. New cambelt fitted but doing this before the change.

Garage says ECU could be overfuelling the injectors at this rev range and this is why the tappetty sound and the fuel problems. Garage suggested they download something to ECU but need this month's disk to do it as disk on computer is out of date. Garage says that download might fix over fuelling!

Would this be correct? How much are injectors for the HDI 90 in the UK?

Thanks.

Reply to
ML
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If it's overfuelling it will , by definition, smoke. It will also go faster. More likely is the timings out. Try another garage or a diesel specialist

Reply to
Duncan Wood

Too much fuelling will equal smoke will equal good performance. Is there any smoke? If performance is flat and its reluctant to rev hard then the ECU is definately in limp mode and timing is then set at a constant which would give you excess diesel knock. You then would expect the MIL lamp to be lit.

The most likely cause of this is either the HP pump position sensor or the rail pressure transducer having failed.

On the HDi you cant have the timing out! Well you can, but it only affects when the high pressure pump pumping strokes happen in relation to engine position. It doesnt make any difference to injection timing- as the ECU does this in response to signal from crank and cam sensors. If the timing on the cam was out- it would set the MIL lamp as the ECU looks for signals from both sensors within a tight window. If one is out- it knows there is a problem.

Injectors either work or don't, however spray pattern deteriorates with age. How many miles on the clock? Due to the good burn with common rail engines, injector fouling is much less of a problem than it used to be. Lets hope is isnt injector problems as they are ~£150 each.

Tim..

Reply to
Tim..

Yeh I was reading that timing in the HDI didn't matter or couldn't be set, so the Haynes manual says anyway.

No there are no warning lights, nothing that tells me there is a problem. It was already on the diagnostics machine and nothing showed up. There is no smoke either and as far as performance goes, there is none of that either but maybe I am expecting more from a 90HP engine!.

There are 96K miles on the clock.

I was thinking, could it be the air temp, air mass meter, air something or other which would account for more fuel consumption. Something which would not show up in the diagnostics?

For that matter, is there anything it could be which would not show up in diagnostics?

Thanks for the help.

Reply to
ML

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