Hi guys,

I'll try to describe this best I can:
When crawling along in traffic, when the engine is almost on idle in gear, it almost feels like the throttle is either 'on' or 'off' and will jump between the two when the throttle is in a certain position (like when I'm trying to maintain this slow crawling speed), causing the truck to kangaroo a bit as it goes along.

- No problems in high speed/revs
- I replaced wiring loom which had oil in it
- Has a new MAF sensor

Is it possible the accelerator position sensor is faulty causing it accelerate and decelerate rapidly in certain positions? It doesn't seem to be very progressive when you move the throttle just a little bit.

Anyone know how I might diagnose it properly?

Thanks very much!

Oli

diagnosis needs a puter...
sounds a possibility, but it could be other things, get it on a nanocom and have a look, if you do most of your own repairs, buying one would save you money in the long run on pot luck repairs.
otherwise, look at the LZIR map, should let you know whos got diagnostics local to you.

Just to understand your problem better:

1. it does not do this when you actually let it idle along, only when you give it some throttle to up the revs a bit faster than idle?

2. you don't mean the normal "cutting fuel" mode when the vehicle is starting to go faster than the intended engine speed and the ECU simply throttles back to the point where it stops injecting diesel and the engine just brakes against the force pushing the vehicle downhill?

If it is nothing mentioned above, the only time I experienced something along these lines was when I ran the TD5 with the air mass sensor disconnected. In cold weather, it would hunt a bit in idle and low speeds.

If you know someone with a Nanocom or similar gadget, it is easy to monitor the throttle pedal sensor. Depending on the TD5 model, it will have three or on some of the older ones I believe two "ways", which you can monitor on the gadget and see if they mess about. Usually an ECU fault will also be logged. I don't think it will be that though.
If you have access to such a gadget, check the crank shaft sensor signal is not noisy either. That may also potentially cause this.

Is it not just that the beast has heaps of backlash in the drive-train (Like all good Defenders have!) and you lack the precision hand-eye-foot-breathing coordination the Defender designers specified as a minimum requirement for all potential owners?

timtheenchanteruk said:

diagnosis needs a puter...
sounds a possibility, but it could be other things, get it on a nanocom and have a look, if you do most of your own repairs, buying one would save you money in the long run on pot luck repairs.
otherwise, look at the LZIR map, should let you know whos got diagnostics local to you.

Click to expand...

Thanks, it might well be time to get a Nanocom..
What is the LZIR map?

oli1 said:

Thanks, it might well be time to get a Nanocom..
What is the LZIR map?

Click to expand...

Click here , the map has two pages.

Members with dianostics are shown with a red circle. Click on the icons near you to see details of the type.

PM those with suitable kit near you.

GerhardB said:

1. it does not do this when you actually let it idle along, only when you give it some throttle to up the revs a bit faster than idle?

2. you don't mean the normal "cutting fuel" mode when the vehicle is starting to go faster than the intended engine speed and the ECU simply throttles back to the point where it stops injecting diesel and the engine just brakes against the force pushing the vehicle downhill?


Is it not just that the beast has heaps of backlash in the drive-train (Like all good Defenders have!) and you lack the precision hand-eye-foot-breathing coordination the Defender designers specified as a minimum requirement for all potential owners?

Click to expand...

It seems to happen mostly at very slow traffic speed, at the point when the engine is neither accelerating or decelerating. It seems to the rapidly accelerate/decelerate slightly causing to judder back and forth, sometimes quite badly if it gets a rhythm going.
It feels like the fuel is getting off too harshly, and/or switching on too harshly when it's on this balance point.

2 other things which I've found on the internet that might cause it, the clutch switch failing or leak in the exhaust (which I fiddled around with a few weeks ago). Will investigate this evening...

Thanks for you help!

Oli

Put your location up, I've got a nanocom in Doncaster if that's any good.

Broken worn carbon disc within the throttle pot????

I had this in a 99 TD5 Disco 2, it went back to a main LR Stealer many times to try and get to the bottom of the problem - they never did.

In the end I just learned to live with it by adjusting my throttle foot in traffic and low speeds. Not helpful, but I've been there.

Thanks for the help guys,

I have found the solution to this problem! When I changed my transfer box to a disco one I have to unbolt the exhaust down pipe. I didn't notice the gasket between the exhaust manifold and down pipe was missing, meaning it was leaking slightly but not enough for it to make a difference in noise.

Replaced the gasket, runs absolutely perfect. Great!

I know you say it's been solved but also check your turbo wastegate is working freely. Give it a good squirt or wd40 and push the rod in and out.