Member Since: 09 Jun 2016
Location: Bromley
Posts: 91
How does the throttle work?
Can somebody explain how the throttle works on the D4? I’m presuming it’s some sort of “fly-by-wire” set up?
Only asking because when I’m in a really chilled out driving mood, and being really gentle on the pedal, the engine sounds as though I’m “feathering” the throttle. Almost like I’m giving the throttle short, sharp jabs really quickly. It’s really odd as the car doesn’t rock and the acceleration is smooth and feathering noise gradually disappears as the revs pick up. If I’m heavier on the throttle to begin with it doesn’t happen but that’s not always ideal when you’re coming out of a sharp bend or there’s a car in front pulling away slowly that doesn’t want a Disco in its boot. It doesn’t happen from standstill, only when I accelerate from a rolling start kind of speed. No issues when kicking down or giving it some beans, only when I’m driving like miss daisy.
Almost sounds like there’s not enough fuel firing in but then you would expect the engine to shudder or the acceleration to be a bit jittery. There’s none of that.
6th Jun 2019 10:22 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5052
Yeah its "fly by wire" get your diagnostic codes read yµ (idµ - eAµ) ψ=mψ
Member Since: 09 Jun 2016
Location: Bromley
Posts: 91
No, the rev counter is steady. Really odd this one.
It’s going in for a service in a couple of months to an indy. I’ll get them to check for faults.
7th Jun 2019 2:09 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5052
It might just be one of the throttle position sensors, diagnostics should point the direction.yµ (idµ - eAµ) ψ=mψ
7th Jun 2019 2:15 pm
patersp
Member Since: 09 Jun 2016
Location: Bromley
Posts: 91
Just for completeness, as I hate leaving threads open ended and maybe this will help somebody in the future.....
I ended up booking the Disco in to my local Indy as we started getting a diesel smell and spots of diesel on the drive after use. Fortunately I was able to demonstrate the noise from the engine and they lifted the engine cover to reveal some smoke coming out.
Turns out the pipe connected to the high pressure fuel pump was not located correctly. Guess it has been working its way looser and looser until diesel started dripping out. They re-seated the pipe and fitted a new clip. Haven’t given it a road test yet as the SWMBO has just picked it up but they said it is no longer surging (that’s the way they described the engine noise).
Best bit is, they only charged me for reading the diags (£42.50 + VAT). Can’t praise them enough. I’m sure the stealers would’ve found something astronomical to charge if I had booked it in there
28th Jun 2019 9:41 am
patersp
Member Since: 09 Jun 2016
Location: Bromley
Posts: 91
Oh well. After a good road-test the noise is still there
I've asked the indy to let me know what faults they found on the diags which I will hopefully have on Monday.
After driving it today, I've come up with a better description of the noise.... It's the 'diesel rattle' and the noise can only be described as the rattle fluctuating between load and quiet a couple of times a second until the revs pick up slightly and it disappears (or becomes quieter).
30th Jun 2019 11:57 am
patersp
Member Since: 09 Jun 2016
Location: Bromley
Posts: 91
Just an update for anybody who is interested.
Went in for a service yesterday at my local indy and they spent a good bit of time trying to diagnose what the noise is. They can clearly hear it and admit it's odd but there are no fault codes whatsoever and, performance-wise, the car is fine. All software is up to date.
So unfortunately there is nothing we can do at the moment. They were very honest and said they don't want to start randomly replacing things without really knowing where to start. Guess this one will have to wait until a failure or error code.
Noticed the "diesel rattle" was very noisy this morning on start-up and for around the first 5 mins of driving (around 5:00 - not too cold).
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