Stuttering for 20 seconds after decelerating

[nickpankovas]

Hi,

Any help appreciated please. I can't get the car booked in with the dealer for three weeks (fully booked, I'm in Dubai).

I have a 99 Discovery V8i 89,000k on the clock. I bought it a couple of months ago, it ran brillliantly when I got it. I have a problem that I first thought was intermittent, but now I realise that it's not. This is what happens.

I get up to a speed of 120kph or over and stay there for a while, then I decelerate for whatever reason.

Then, when I try to accelerate, the engine runs very badly as if a few cylinders are not firing.

20 seconds later, it recovers and the problem goes away. There doesn't seem to a problem at speeds of less than 100kph, or at least it's not noticeable. It does however in general doesn't seem as smooth as it was when I got it.

Regards

Nick

 

[joey]

VSS (vehicle speed sensor) has gone bad..... less than $80US and 10 minutes to change....

 

[nickpankovas]

Thanks for that, I'll try that tomorrow

Regards,

Nick

 

[nickpankovas]

I took it to the local garage (can't get into the dealers) yesterday and after a couple of road tests, they thought it was more a vibration problem and not an engine problem. They believe it is linked to the prop shafts and/or transfer case. There are no speedo or rev counter fluctuations, they are steady throughout. There is a definite 'clunk' when you go into Reverse from Park. They say that these facts helps them to confirm their diagnosis. They also reckon that it's normal on most Landrovers and that their owners just live with it as it's very expensive to trace and fix. Since the vehicle has only done 88,000km I'm very surprised that it could be something like this.

 

[joey]

What you are stating are two different issues. One is the VSS first post... vehicle has a lose of power, and hesitation. above 120Km Per hour or about 60mph.

Second issue sounds like it may very well be a U-joint or similar... What year Disco is this? Could also be tires out of balance.

 

[nickpankovas]

Joey, thanks for taking an interest, much appreciated. It's a 1999 Disco 1. Yes I am confused myself. I had fun explaining it at the garage also, in the end I had to get to a motorway to show them.

It felt like a loss of power but perhaps I am subconsciously easing off the gas because of the problem. The garage say it's not an engine problem (which I thought) but it's vibration. I can cruise at any speed OK (which is why I didn't suspect tires out of balance), the problem is that when I slow down from say 120kph or above (>=75mph) to say 90kph (56 mph) and then accelerate again i get the deep vibration problem for only a matter of 10-20 seconds then the problem goes away.

 

[joey]

In this case... regardless of what the shop states, I would start by basic tune up (plugs, wires, fuel filter, air filter) then I would run some sort of fuel injector cleaner through the system (here in the US I use a product called Seafoam) One in the tank, one in the intake plenium and one in the oil... may very well be the valves starting to get carboned up.

Beyond that, I may be at a lose for what is causing the issue.

 

[Moose]

Loose motor mounts? Bad (or going bad) U-joints in the driveshafts?

 

[nickpankovas]

I got it back from the garage today. They changed the front propshaft and checked the other (apparently seems fine). Unfortunately the same problem exists and they are saying it's the transfer case and maybe they could fit a reconditioned one for me if I really can't live with the problem. I did take it out for a drive today and noticed that when the vibration starts I can knock the gear down to 3 and it's an instant fix. That leads me to not suspect the motor mounts or the U-joints. We're one step further in that I know know it only happens in top gear (Drive). I'll use this 'workaround' (dropping to 3) for the time being.

 

[Jeff Discos]

I'd change the VSS if I were you. Knocking it down to 3rd gear to fix the problem is a key sign that the problem IS the VSS.