Member Since: 28 Aug 2006
Location: Mid-sussex
Posts: 2021
I did the normal drive to work, 75 miles of mixed driving. Normal mpg on the dash is 31.1 over the long term. One day is not enough to draw a true comparison, but 34.3mpg showing. If that is sustained that is a great improvement. I shudder to think about the additional fuel cost of not having that 20p fuse over 10 years of ownership
The response on acceleration is so much better. No lag and gurgling sound, just instant power. I have only ever driven my D3, so had nothing to compare to. I am surprised that the dealer that serviced the car for over 7 years never noticed.
Message from this experience - if you have an 05 D3, check that you have fuse 17 fitted.2005, TDV6 S, Auto, 190k miles, owned from new, V8 Brake Upgrade, Nancom Evo, RLD protector, BAS EGR blanking & Remap, separate ATF cooler, changing all the fluids ahead of time.
3rd Nov 2014 7:18 am
yogi972
Member Since: 05 Jun 2011
Location: Kineton
Posts: 3373
I'll be lifting the lid later then
3rd Nov 2014 8:03 am
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Is the Disco still triggering a permagrin Barn1e?
It would be interesting to know how the mpg goes, but I suspect you may be enjoying your remap and throttle response for a while.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 28 Aug 2006
Location: Mid-sussex
Posts: 2021
Robbie, the problem I have now is that I like to use the added performance during acceleration, so am not really doing a fair comparison of old mpg against new. However, even with my new driving style, my average mpg has improved by almost 2 mpg. I have also noticed that the car pulls better for longer in the same gear before changing down a gear (say when ascending a hill).
I have also turned the radio off because I like the sound of the effortless acceleration.
And yes, the remap is probably coming into its own.
I am think about posting a new thread called "I bought a new D3 for 20p" 2005, TDV6 S, Auto, 190k miles, owned from new, V8 Brake Upgrade, Nancom Evo, RLD protector, BAS EGR blanking & Remap, separate ATF cooler, changing all the fluids ahead of time.
5th Nov 2014 7:30 am
twoakers
Member Since: 15 Nov 2010
Location: Harwich
Posts: 367
Great thread of interest to all Disco 3 owners
Great thread Barnie and Robbie
Followed with interest. Will go and check my Fuse 17 shortly
In the final stages of a Turbo change with the body on
The stiffness of the turbo actuator on the old one has convinced me it was the right thing to do 8)
Suggest you do a nice new post about the benefits of having ya MAF working correctly Cheers, Dave in Essex
D3 07 TDV6 HSE
Clubs - Turbo changed, EGR valves replaced, General Grabber ATs, Hawkeye FC reader, Front/rear wishbones, manual gearbox change, autobox flush, cam belt change, HPFP belt change, oil pump change....
Coachman Laser 650/4 caravan
Amateur Radio Callsign - G8PAI
Playing with Big Boys Toys!
5th Nov 2014 8:31 am
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Barn1e wrote:
With the Connector disconnected, the Voltage at Red/Blue , Red and Yellow are all 4.6v.
With the connector attached and car at tickover, the voltages are 3.0v, 5.0v and 3.0v respectively.
When I rev the engine to 2000rpm, none of those voltages change.
I have looked at several videos on testing and assume I should always be measuring to the earth, but am not sure which of the three live wires is doing what. However, if none of them change with the revs and therefore the airflow, does that sound like the MAF has failed.
A few questions that are worth answering for those who may read this thread in the future.
The D3 has a single hot-film digital MAF with 4 wires:
Red/Blue - Power
Red - MAF signal to ECM
Yellow - Intake Air Temp to ECM
Black - Common Signal ground for IAT and MAF to ECM
The D4 3.0L has 2 MAFs to feed the 2 turbos. The rear MAF has 3 wires:
Red/Blue - Power
Brown/Black - MAF signal to ECM
Brown/Red - Signal ground for MAF to ECM
The front MAF has 4 wires:
Blue/Brown - Power
Grey/Red - MAF signal to ECM
Red/Brown - Intake Air Temp to ECM
Brown/Red - Common Signal ground for IAT and MAF to ECM (from a splice this is common with the other MAF)
Click image to enlarge
You are expecting vehicle voltage on the Power side, shown here with the engine running:
Click image to enlarge
The MAF signal should show the 5v reference voltage, minus a bit of voltage drop:
Click image to enlarge
The Intake Air Temp is a 3.3v input from the ECM, which is then varied by the temperature:
Click image to enlarge
The Ground is a signal ground provided by the ECM. As such it will be a less noisy source than direct to battery if you are connecting an oscilloscope. Clearly the ground has to be good with negligible resistance. If the signal ground is poor (pretty common fault on a D3 caused by corrosion at the ECM) it will cause problems with the MAF(s) and the IAT.
The MAF signal is a constant voltage with a variable pulse width (PWM). If you have an o'scope or a DMM with the ability to show a frequency (such as my Fluke shown here) you can check that the output response to throttle is smooth, If it isn't then the MAF may be dirty or failing. If the frequency changes at idle when tapping on the MAF then either it or the connections are suspect.
No signal from the MAF:
Click image to enlarge
Signal from the MAF with varying throttle:
Click image to enlarge
Change of throttle, read from inside the vehicle:
Click image to enlarge
If you have a diagnostic tool with live data, such as a GAP BT IID Tool used here, you can also display the MAF output as calculated by the Engine Control Module. This is processed data rather than raw but it tells you what the computer is using in grams per second and is shown with engine RPM, MAP and IAT:
Click image to enlarge
Displayed as a graph:
Click image to enlarge
It is much easier to check the raw MAF output with an o'scope if you have or can borrow one as you can see the complete waveform. I strongly recommend using proper backprobes with fine pins when conducting testing as you are less likely to short a connection and it avoids damaging the wires or the insulation:
Click image to enlarge
Click image to enlarge
Click image to enlarge
Click image to enlarge
You should only pierce insulation in situations where you do not have access to connectors. If you do pierce insulation only do it with the fine needle type of probe:
Click image to enlarge
You can just see the needle in the jaws:
Click image to enlarge
The needle hole is very small and just visible in this photo but it still needs protecting afterwards with liquid tape or waterproof insulation tape:
Click image to enlarge
Hope this helps someone. If so, I will tidy it up a bit and create a version for the wiki.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 28 Aug 2006
Location: Mid-sussex
Posts: 2021
Robbie, I was clearly in very capable hands (via this thread) last Sunday.
Hopefully there will not be many people trying to diagnose a missing fuse during manufacture! However, being able to diagnose a failed MAF using this guide would be helpful because in my experience the car still starts and drives ok(ish), so the fault is not immediately obvious, be that a missing fuse or a failed sensor or wiring.
2005, TDV6 S, Auto, 190k miles, owned from new, V8 Brake Upgrade, Nancom Evo, RLD protector, BAS EGR blanking & Remap, separate ATF cooler, changing all the fluids ahead of time.
6th Nov 2014 8:30 am
GuySA
Member Since: 07 May 2013
Location: Richards Bay
Posts: 6
OMW, I am so glad I found this thread.
I have had a 2008 Disco 3 for the last 2 years and it has always had a bit of hesitation on pull away ans has been a bit smokey.
Since I bought an IID Tool I had noticed the maf reading was 0 and I was constantly getting the P0100 fault, but had assumed this was just how it was.
After reading this I decided to check fuse 17 on my car and found that the 15A fuse was in position 19, which is unused, instead of position 17. I switched it over and the difference is amazing.
I can't see why any of the previous owners would have moved the fuse and can only think it may have come from the factory like this.
I wonder how many others are driving around with a non-functioning maf.Arguing with an engineer is like wrestling in the mud with a pig.... After a while you realise you are dirty and the pig likes it.
4th Mar 2015 8:05 am
Barn1e D3 Decade
Member Since: 28 Aug 2006
Location: Mid-sussex
Posts: 2021
Guy, great to hear that thread was of use. I initially thought I was the only one in the world, but looks like there are a few of us around, and probably more that dont know. Welcome to the very select club of people who know what fuse 17 does and know if they have it 2005, TDV6 S, Auto, 190k miles, owned from new, V8 Brake Upgrade, Nancom Evo, RLD protector, BAS EGR blanking & Remap, separate ATF cooler, changing all the fluids ahead of time.
4th Mar 2015 1:10 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
GuySA wrote:
OMW, I am so glad I found this thread.
I have had a 2008 Disco 3 for the last 2 years and it has always had a bit of hesitation on pull away ans has been a bit smokey.
Since I bought an IID Tool I had noticed the maf reading was 0 and I was constantly getting the P0100 fault, but had assumed this was just how it was.
After reading this I decided to check fuse 17 on my car and found that the 15A fuse was in position 19, which is unused, instead of position 17. I switched it over and the difference is amazing.
I'm really glad the thread and Barn1e's determination to fix his issue has helped someone else. Another good reason to invest in a good diagnostic tool too.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 14 Jan 2015
Location: Noord-NL
Posts: 14
I have a 2005 HSE for a month now and just checked fuse 17. It is there but it is a 15A. The instruction manual also says it must be 15A.
So not all 2005 models are missing the fuse.
7th Mar 2015 9:26 am
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Yes, it is very rare and so far I only know of 2 occasions where the suspicion is that it was like this from manufacture / delivery. There may be others but with some D3s over 10 years old and multiple owners it is impossible to know.
Personally I have never seen one with a missing fuse and the incident in this thread was the first time I had heard of one.
Land Rover - Turning Drivers into Mechanics Since 1948
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