High Speed Power Loss

Hi all,
TD4 Manual 2003. The car always starts ok hot or cold. It has developed a power loss at speed on long hills and it is more than the just the gradient or the length of the incline causing it to slow. If you approach a long fast hill at 70/80 ish ( about 3k rpm )the vehicle will start to slow as though the fuel is being gradually turned off. There is no smoke when this happens and wondering if the fuel pump gets lazy before it fails completely. On the flat the car will build to 100 mph ok. The fuel filter ( Mann ) was changed at the previous service my me about 10k miles / 12 months ago. I think this problem occured before then but very rarely. It has now become more pronounced to a point where I am reluctant to overtake on hills where previously the car would just fly on up. The fuel pump is just in front of the offside rear wheel. There seems to be so many variances to freelander problems and I am reluctant to pay the main dealers on a trial and error basis to fix the problem. Anyway, I should be able to repair most things if they are not to heavy or awkward to get at. Also, is their any Rave gen for these later but pre-facelift vehicles? Many thanks in advance.

I’ve taken fuel pressure sensor signal readings from a normally operating TD4.In the hope that they may help identify power loss problems on my own vehicles should they occur in the future.

Low pressure sensor (located on the bulkhead) voltmeter connected between battery earth and green cable:

Ign ‘on’ and pump heard priming- 3.9 to 4volts.
Engine running both at idle and up to 3000rpm- 4 to 4.1volts.

High pressure sensor (located at the end of the fuel rail nearest battery) voltmeter connected between battery earth and blue/black cable:

Ign ‘on’ – 0.5volts.
Engine idling- 1.28volts.
3000rpm- 1.96volts.

You might try taking readings if you are confident with a multimeter and take care when the engine is running. Good luck.

Landrover have issued a service bulletin about a corrosion problem with the plug for the fuel pressure regulator on the td4 that causes a misfire or loss of power especially under load as the cpu gets a false voltage signal which in turn shuts the fuel delivery down hence loss of power, you get no fault codes as the cpu thinks all is working ok. There is a modified plug and wiring for the fuel pressure regulator. The landrover part No is YMQ503320 and It’s a easy fit
If you are getting a managment light on then may be the MAP sensor, which LR call multi pressure manifold sensor (which normally gives a fault code). One way to check the MAP is remove from the inlet manifold clean it with a contact cleaner and refit and see what the difference is as we have also had a few td4 with that fault as well. Dont spay the cleaner directly into the sensor but a 90 deg to it allowing the cleaner to go in a less pressure shake all the gunge out a few times

Hi,

See my post as to how I fixed mine. Might be the same issue, deffo worth a try. Good luck

http://www.landyzone.co.uk/lz/f9/td4-lack-power-70mph-fixed-77147.html#post762900

Hi all,
Thanks for the help. Have unplugged all connections that I can find and given them a squirt of WD, although they all looked clean and not corroded. No difference to problem. Pulled off the vacuum pipe on the turbo and it went clunk. Would there still be a vacuum holding things on a cold engine that was left overnight? Have changed the solenoid and the little filter to air. Old filter was a bit blocked when trying to blow through compared with the new. New one was easy. Car seems much more responsive so hope this has done the trick. Will be able to check over the next week or so with a run up the A303 and those big long hills. Fingers crossed. Will let you all know how it goes.

Hi,

I don't think it should hold the vacuum overnight, but if the little filter was blocked then it wouldn't be able to release that vacuum by venting through that filter to atmosphere. Hope that it sorts your problem anyway

Hi all,
It seems that I have fixed it with the remedy from Kungfu0210. Solenoid and the small filter available off the shelf and fitted quite easily. Well done and thanks for all the help. Until the next problem, cheers-------!

That's great, glad that you've got it sorted