chips - and their claimed increase in MPG

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NikTheGeek

NikTheGeek

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Wigan
Found this on another forum about a P38 Diesel Range Rover P38:

"As for fuel economy, I'm currently getting mpg in the 30's, even with the aircon on. I have tried it without the chip (plug in module) and mpg drops to very low 20's and there is a very noticeable drop in power."

I understand the drop in power, but really that much difference in mpg? I've also heard (on here I think) that having one chipped confuses the onboard computer and that it gives incorrect readings because it doesn't take in to account the extra fuel squirted in. If that were true, that would assume that the fuel measurement was made AFTER the chip, but the chip doesn't go in the fuel line. So even if more fuel is being squirted in, the fuel pump (or whatever measures fuel use) should see the extra.

So with all the claims about increased mpg with chipping, what gives?

Go easy, I've never chipped a car and I'm not a mechanic. Just curious.... :)

Nik
 
NikTheGeek said:
Found this on another forum about a P38 Diesel Range Rover P38:

"As for fuel economy, I'm currently getting mpg in the 30's, even with the aircon on. I have tried it without the chip (plug in module) and mpg drops to very low 20's and there is a very noticeable drop in power."

I understand the drop in power, but really that much difference in mpg? I've also heard (on here I think) that having one chipped confuses the onboard computer and that it gives incorrect readings because it doesn't take in to account the extra fuel squirted in. If that were true, that would assume that the fuel measurement was made AFTER the chip, but the chip doesn't go in the fuel line. So even if more fuel is being squirted in, the fuel pump (or whatever measures fuel use) should see the extra.

So with all the claims about increased mpg with chipping, what gives?

Go easy, I've never chipped a car and I'm not a mechanic. Just curious.... :)

Nik
Click to expand...

The fuel computer does not know about the extra fuel being squirted in, not sure on the exact means of calculation on the P38 but it will most likely be based on injector timing from the ECU, since the power box is fitted in the line to the FIP the extra fuel cannot be accounted for by the fuel computer, on mine the computer reading was up to 4 mpg optimistic compared to the brim to brim figure.
I've run mine with and without the power box, if you use the extra power quite naturally it used more fuel, however on the motorway cruising at 70 mph it was very slightly more economical with the power box, I but this down to the fact that down shifts on inclines and torque convertor unlock occurred less.
The dash computer is accurate with the power box removed, long term brim to brim and the dash computer both work out at 24 mpg unless on a long run when it can go up close to 30 mpg.
A good remap may be different in that if the calculation is done from injector timing it's possible the dash figure will still be accurate.
 
Fair enough. I'll cross that one off the future list as I'm not interested in more power. But when I tow my boat 300 miles each way on holiday a few extra mpg wouldn't go amiss.

Next thing on the list is an injector check/service. I assume they need adjusting after a time and its done 98k. I also assume that if the pattern isn't a fine mist, it'll use more fuel for a given power...

tnx

Nik
 
NikTheGeek said:
Fair enough. I'll cross that one off the future list as I'm not interested in more power. But when I tow my boat 300 miles each way on holiday a few extra mpg wouldn't go amiss.

Next thing on the list is an injector check/service. I assume they need adjusting after a time and its done 98k. I also assume that if the pattern isn't a fine mist, it'll use more fuel for a given power...

tnx

Nik
Click to expand...
Mine is 110K, the injectors have never been touched. The biggest influence on fuel consumption is your right foot and overall driving technique, for example holding the auto in third on speed limited inclines is more economical as it will run with the torque convertor locked whereas in 4th the torque convertor would be unlocked. Likewise 3rd can be used when slowing or descending to keep the torque convertor locked for longer so operating the overrun fuel shut off.
If it's over fueling due to worn injectors it will smoke.
I get better than 20mpg with a caravan on the back.
 
For the cost of the ecu being reprogrammed, it would take you ages to Recuperate your money back for it to be worth it, unless you do a high milage :)
 
defender300td1 said:
For the cost of the ecu being reprogrammed, it would take you ages to Recuperate your money back for it to be worth it, unless you do a high milage :)
Click to expand...

You can get plug in units that are fully adjustable for about £75

Don't know if they do a plug in jobby for the p38 though ?

Works well on the l322 anyway :)
 
2.0_hippo said:
You can get plug in units that are fully adjustable for about £75

Don't know if they do a plug in jobby for the p38 though ?

Works well on the l322 anyway :)
Click to expand...

You can get plug in ones , but as with anything you only get what you pay for, to do it properly ecu get reprogrammed . That can be reversed if needed mega bucks £409+
 
Datatek said:
The biggest influence on fuel consumption is your right foot and overall driving technique, for example holding the auto in third on speed limited inclines is more economical as it will run with the torque convertor locked whereas in 4th the torque convertor would be unlocked. Likewise 3rd can be used when slowing or descending to keep the torque convertor locked for longer so operating the overrun fuel shut off.
If it's over fueling due to worn injectors it will smoke.
I get better than 20mpg with a caravan on the back.
Click to expand...

No smoke. I get 16 without anything on the back. Ok, TBH I get 21-22 on a run it seems.

How do you do the manual bit? Can you drop the stick out of auto into third whilst driving? Never tried it for fear of knackering the box. Or do you just press the manual button coz I've never figured out what that does. Nothing lights up when you press it!! :)

Nik

Edit: figured it out. It's in the manual. Didn't know you could go between D and 3 and back....
 
Last edited:
defender300td1 said:
You can get plug in ones , but as with anything you only get what you pay for, to do it properly ecu get reprogrammed . That can be reversed if needed mega bucks £409+
Click to expand...

Iv never wanted a remap for this reason

I like having the ability to turn of or adjust the power when I want

Iv used plug in Jobbys on all my cars and never had any complaints
 
Datatek said:
The biggest influence on fuel consumption is your right foot and overall driving technique.
Click to expand...


+1 on that Datatek!!

I get 26+mpg on my L322, just cos of the way I drive it. Smooth and gradual acceleration, reading the road ahead, no sharp brakeing and accelerating. I always have to laugh at the people who say my Rangie must slurp fuel like there's no tomorrow, then are well surprised when I show them the MPG figures.

P.S. I've always maintained that the real reason TD6's kill gearboxes is cos people drive them like they're F1 race cars. 2.5 tonnes of 'Luxury' 4x4 should not be driven like a Ferrari!! Something's bound to give!
 
Discotigger said:
+1 on that Datatek!!

I get 26+mpg on my L322, just cos of the way I drive it. Smooth and gradual acceleration, reading the road ahead, no sharp brakeing and accelerating. I always have to laugh at the people who say my Rangie must slurp fuel like there's no tomorrow, then are well surprised when I show them the MPG figures.

P.S. I've always maintained that the real reason TD6's kill gearboxes is cos people drive them like they're F1 race cars. 2.5 tonnes of 'Luxury' 4x4 should not be driven like a Ferrari!! Something's bound to give!
Click to expand...

Very true words I think

Course your right, the boxes would last if they were all driven well

If you accelerate slowly the gearbox will never have to be subject to the large amounts of torque that kills it
 
Last edited:
Yep, very true.

When I first got my RR I thought of getting it chipped/remapped, but decided against it very quickly. I'm fortunate that:

If I want to go fast I just jump in the wife's Mondeo ST220 (it used to be mine, but it now has her private plate on it!!)!

If I want to go really fast, I just jump on my Kawasaki ZX6R!

If I want to go everywhere in total style and luxury, I take my Rangie Vogue!! And...WHY THE RUSH!!
 
Discotigger said:
Yep, very true.

When I first got my RR I thought of getting it chipped/remapped, but decided against it very quickly. I'm fortunate that:

If I want to go fast I just jump in the wife's Mondeo ST220 (it used to be mine, but it now has her private plate on it!!)!

If I want to go really fast, I just jump on my Kawasaki ZX6R!

If I want to go everywhere in total style and luxury, I take my Rangie Vogue!! And...WHY THE RUSH!!
Click to expand...

All good words

It's nice to have the power though in the RR for when you need it like overtaking

As the td6 is pretty sluggish without one tbh

Just because you have a chip fitted doesn't mean you have to use the extra power

I found mine drives much better with one fitted

It changes gears sooner and holds them for shorter as compared to standard

Less gear changes too

So surely in one way, less wear on the gearbox ??
 
Discotigger said:
Yep, very true.

When I first got my RR I thought of getting it chipped/remapped, but decided against it very quickly. I'm fortunate that:

If I want to go fast I just jump in the wife's Mondeo ST220 (it used to be mine, but it now has her private plate on it!!)!

If I want to go really fast, I just jump on my Kawasaki ZX6R!

If I want to go everywhere in total style and luxury, I take my Rangie Vogue!! And...WHY THE RUSH!!
Click to expand...

If I want to go slow, I jump in the wifes Micra

If I want to go slower, I jump in the Range Rover :)
 
NikTheGeek said:
No smoke. I get 16 without anything on the back. Ok, TBH I get 21-22 on a run it seems.

How do you do the manual bit? Can you drop the stick out of auto into third whilst driving? Never tried it for fear of knackering the box. Or do you just press the manual button coz I've never figured out what that does. Nothing lights up when you press it!! :)

Nik

Edit: figured it out. It's in the manual. Didn't know you could go between D and 3 and back....
Click to expand...
You can change down with the stick all the way to 1st in the move, the ECU will only effect the change at the appropriate speed, I use 3rd a lot and 2nd occasionally.
I have never managed to get mine down to 16 even with the caravan in the Pennines, either you have a very heavy foot or the car is sick, has a binding brake, lack of oil in the diff's or transfer box etc.
I re-set the computer on every fill and leave it showing the average consumption, I keep up with the traffic while at the same time always trying to get the consumption figure to improve. Sad I know:rolleyes:
 
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