Thread: Discovery 2 TD5 gutless on hills

Originally Posted by OffTrack

What the modulator does is prevent "wastegate creep". As the graphic attempts to show without the modulator the wastegate starts opening at something like 7-8 psi. The modulator regulates the pressure reaching the wastegate actuator, so the wastegate can remain fully closed until the ECU determines it needs to dump boost.

cheers
Paul

So I should reconnect mine then?

Originally Posted by OffTrack

I guess if your benchmark is a drive to local lawn bowling club whilst staying well under the speed limit it might appear it's been driven over it's limits. However the rev limit on the Td5 is a shade under 5000rpm under power and about 5500rpm on the over-run. I know those figures might be slightly shocking to the "anything over 3000rpm is abuse" brigade.

I'm slowly beginning to understand why my TD5 has 360,000 KM's and still has the original head gasket, Bob

Originally Posted by hippo45

So I should reconnect mine then?

I would. The D2 mapping is design to run with it in place and it will make the engine a little bit more tractable



The above image is a plot of manifold pressure vs rpm from a random Nanocom recording from my D2. You'll see from the graph that in pretty normal usage boost is getting up around 0.5bar/7psi at around 2000-2250rpm so the modulator will let the engine make more boost through to around 3000rpm. So basically it gives a bit more power in the band that you are most often using.

cheers
Paul

Looks a familiar plot. I did a scatter plot a few months back out of interest and it had exactly the same dog leg profile.

Steve

The few vehicles I have seen with the modulator bypassed, improved the driveability after they were replaced with new and reconnected.

JC

Originally Posted by ramblingboy42

I agree with Northiam, I think you expect too much, find someone else with a similar vehicle and compare, methinks you are writing here without doing your own testing.

From Monday to Friday I drive a Nissan Hardbody NP300 with over half a ton of spares and equipment in the back, it also has a 2.5litre turbo diesel and is rated at 98kw and 304nm. If expecting my Discovery TD5 with only me in it to drive as good or even slightly better then the Nissan hardbody then

Originally Posted by bunduguy

From Monday to Friday I drive a Nissan Hardbody NP300 with over half a ton of spares and equipment in the back, it also has a 2.5litre turbo diesel and is rated at 98kw and 304nm. If expecting my Discovery TD5 with only me in it to drive as good or even slightly better then the Nissan hardbody then

Where that logic falls down is that the Dual cab NP300 has a tare/unladen weight of between 1540kg (2wd) and 1794kg (4wd) depending on spec. The lightest D2 (a base spec manual V8) was 2020kg but the top spec D2 Td5 with ACE and SLS would weigh just over 2200kg.

So a NP300 with 500kg of gear in the back could be anywhere between 160kg lighter and 80kg heavier than a top spec D2 Td5.

Power specs aren't that different either as the 2003/2004 models had 101kw and 340nm in Euro spec. The ROW map that was used on the SA vehicles is supposed to be slightly detuned to accommodate poor fuel quality, but I've never seen power/torque specs to confirm this.

Reading back to your first post, the 9.36kpl translates to 10.7l/100km, which isn't too bad. I see similar on my 2000 Td5 on longer 100-110kph trips, but this is a bit off from a couple of years ago when I was getting into the mid-high 9's (around 10.3k/l) on long trips.

Kickdown should really see the engine rev out smoothly into the mid-3000's. As PhillipA posted earlier the Td5 auto will rev to around 4200rpm before shifting up providing you have the throttle in the kickdown region. It's worth trying out a standing start with full throttle on a quiet bit of road - if the engine won't rev into the 4000's before shifting then something is amiss.

Paul

Originally Posted by bob10

I'm slowly beginning to understand why my TD5 has 360,000 KM's and still has the original head gasket, Bob

No, most likely you are misunderstanding, and the real reason is lack of plastic head dowels...