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rover_45
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Discussion Starter · #1 ·
My 620 TD has plenty of power and good, smooth acceleration through the gears. However, when I am cruising on minimum throttle in any gear, especially below 2000 rpm, the engine runs lumpy and the car "kangaroos". What could it be - air getting into the fuel system, a faulty injector, the MAF sensor? Any ideas?
 

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Try disconnecting the EGR vacuum feed and plugging the now free pipe. If the EGR valve is sticking that will upset the performance, (The EGR valve is only actuated under cruising speeds at partial throttle openings).

If that doesn't help check the usual culprit of the wire from number 1 injector getting frayed or broken. Also check that all fuel unions are tight and also the filter. Also check the priming bulb isn't defective and letting air into the system.
 

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Yeah i'd go with E_T_V on that and also check see if your brake lights are going off when they are supposed to, sticking brake sensor can cause all sorts of problems too...
 

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rover_45
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Discussion Starter · #4 ·
EGR valve

Thanks a lot E_T_V. I disconnected the EGR vacuum pipe and plugged it, and the problem has been solved.

Can the EGR valve be repaired? Does it really matter if I don't reconnect the EGR vacuum pipe?
 

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It doesn't really matter if it doesn't work so long as it isn't stuck open. IT is supposed to reduce NOx emmisions but as these aren't tested during an MOT then it won't make any difference to you.
 

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E_T_V said:
It doesn't really matter if it doesn't work so long as it isn't stuck open. IT is supposed to reduce NOx emmisions but as these aren't tested during an MOT then it won't make any difference to you.
yep
i have mine blanked off and it went thought the smoke test no probs
 

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E_T_V said:
Try disconnecting the EGR vacuum feed and plugging the now free pipe. If the EGR valve is sticking that will upset the performance, (The EGR valve is only actuated under cruising speeds at partial throttle openings).

If that doesn't help check the usual culprit of the wire from number 1 injector getting frayed or broken. Also check that all fuel unions are tight and also the filter. Also check the priming bulb isn't defective and letting air into the system.
Hello.
At town speeds my 620 Diesel drives perfectly, but under and after hard acceleration the car 'kangaroos' very badly, particularly at motorway speeds. I have disconnected the MAF sensor, plugged the EGR line and wrapped the bulb tightly in cling film, all to no avail.
The 'wire' to number 1 injector is definately frayed, but looks only to be a fuel return pipe - I will replace it when I can, but don't see why air in the return line would cuase a problem anyway?

Many thanks for any responses
 

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There are two things comming out of number 1 injector. The first is a pipe for returning fuel to the tank. If it isn't leaking then it is fine.

The second is a wire running out of the injector down toward the injector pump.
This wire senses when the injector is open and is used to tell the pump how ti time the injection pulses. If this wire becomes frayed (it happens commonly) then the injection pump gets confused and goes on strike (lights up the engine warning lamp and goes into limp home mode). You need to fix this wire to avoid it shorting out on anything. It is a screened/shielded cable I think which means there is an outer braid of wire on the outside and inside that it the signal cable which runs to the ECU. If the fraying has caused the signal and the shield cables to touch then the fuel pump is probably not getting the signal reliably.
 
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