On my 98 Land Rover Discovery LE my new UG EM Plus says it finds protocol 9141 and uses the MAF sensor to calculate fuel usage when the MPG sensor setting is "Auto". However, the MPG displayed while driving, both average and instantaneous, is wildly high, like 1800 miles per gallon, and the DTE is also off the chart, like 36,000 miles, until I stop moving and then it is 442.4 sitting still. This is after setting the engine size and gas tank size and a full tank of 91 octane 100% gas with the UG reset via the up button to full tank and driving 44 miles.

I watched the ultra gage MPH (which was running 5 MPH less than the speedo and 2 to 3 MPH less than my GPS) and adjusted the mileage calibration to 1.036 to make the UG MPH match the GPS MPH, but the fuel calibration said "< 1/4 can't adjust". I assume the Lannd Rover's VSS is OK as the speedo is steady and the UG MPH is steady, so is there another sensor for fuel usage that could be malfunctioning and screwing up the MPG? BTW, if I set the "force MPG sensor setting" to either MAF or MAP, the MPG gages all disappear from the gage pages and from the gage list.

The Land Rover runs well and the check engine light is generally off, although now and then code P1314 is set for which reported fixes are cleaning/replacing the crankshaft position sensor or cleaning a dirty intake plenum chamber and hoses; the truck has new spark plugs and wires which eliminated previous misfire codes before the UG was installed.

Does your vehicle actually have a MAF sensor?
For vehicles with MAF, the MPG should be fairly accurate out of the box.


Let's do a global reset and start over. Please execute the following command, with the ignition in the RUN position, Engine OFF:
MENU --> Ultragauge Setup... Restore ALL Defaults

The VSS from the ECU is passed to the display unaltered. If it is 5MPH low, then run the Distance calibration.


Once reset, watch the MPH and MAF1 gauges for abnormal readings. Since the MPG readings were crazy high, either the MPH is reading very high, or the MAF is reading very, very low.

The "<1/4 can't adjust" means you have not traveled a distance far enough after the cal was started.

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

"Does your vehicle actually have a MAF sensor?"
Yes it does

"Let's to a global reset and start over."
Done

"Once reset, watch the MPH and MAF1 gauges for abnormal readings. Since the MPG readings were crazy high, either the MPH is reading very high, or the MAF is reading very, very low."

MPH was close before; about 5 low at 50 indicated on the speedo;the speedo seems to be 2 to 3 high compared to my GPS.
After restoring all defaults, optimizing the 9141 (optimized setting 43) and adding MPH, MPG, MAF1, and MAF2 to gage page 1, I started the engine and MAF1 and MAF2 were .10 at idle and .17 to .18 at 2000 RPM. The manual says the MAF1 range should be 0 to 655.35 so these readings are very low. Does this indicate a malfunction of the MAF, or is a different protocol needed for a 1998 Land Rover Discovery?

Its more likely that the MAF is good and that the ECU is not providing the output correctly. However, there is another possibility.
Can you run the following:


MENU --> Ultragauge Setup.. --> Factory test.
The ignition must be in the RUN position (engine off)


When the test finishes, please take a picture of the screen and attach it to this ticket.

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

factory Test run on UG plus in 1998 Land Rover Discovery LE 4.0 V8

Some ECUs scale the MAF output. However, based on the factory test results, your ECU does not, or atleast the ECU is not reporting that it is scaling the output. If the ECU is scaling the output, running the Fuel calibration will solve the issue. However, as we have never heard this issue from any other Discovery owner....we suspect there is an issue with your vehicle.
Check with the service department of your local dealership to see if there is a general firmware update available for your vehicle. In general dealers are resistant to helping when there is nothing in it for them. So it is generally best to speak in terms of getting the update just to make sure you have any safety and emissions updates.

Alternatively, check with a Discovery specific forum to see if others have had this issue with the MAF output.

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

I've been reporting this issue on landroverforums.com on the Discovery 1 forum and asked for others with UltraGages to let me know what readings they are seeing for MAF1 and MAF2. So far no responses, but I'll let you know if I hear back.

BTW, it was on this forum that I heard about UltraGage and it seems to be the best forum for my specific model. Unfortunately the nearest Land Rover dealer is several hours away, but perhaps I can inquire about updates by phone. 1998 is the last year for the Discovery 1, so I assume it should have the most recent firmware for the model. I found this explanation of the MAF operation in the D1 forum archives.

"The "hot wire" type mass air flow sensor is mounted rigidly to the air filter and connected by flexible hose to the plenum chamber inlet. The sensing element of the MAF Sensor is a hot wire anenometer consisting of two wires, a sensing wire which is heated and a compensating wire which is not heated. Air flows across the wires cooling the heated one, changing its resistance. The ECM measures this change in resistance and calculates the amount of air flowing into the engine. As there is no default strategy, failure will result in the engine starting, and dying when it reaches 550 rev/min, when the ECM detects no MAF Sensor signal. The fault is indicated by illumination of the malfunction indicator light (MIL) on North American specification vehicles."

So...are you saying the ECU uses unscaled data and the reporting function is separate from the calculations used for the engine management? Any chance the UG EM Plus treats MAF and MPG differently than earlier models? Is 9141 the correct protocol for my 98 Discovery 1?

UG has not changed its core MAF/MPG function in years.

The ECU continuously reads the MAF sensor. It uses the data to control the air/fuel mixture.

The OBDII specifies the details of reading the MAF sensor via the OBDII.
The Manufacturer has the option of providing the data as per the standard or scaling the data. Ultimately its still the same data. For example:
if the MAF output is 20g/s, the ECU can report 20g/s via the OBDII, or it could report 200 and mark the parameter as scaled by 10. So to use the parameter the g/s = value/10. In this case g/s =200/10 =20. So the result is the same. Your vehicle is not reporting scaling. Hence the value should be the actual output of the MAF sensor in g/s.
Since it is near zero, something is wrong. I doubt the MAF sensor is bad, otherwise the Check engine light would be on and the vehicle would not run well, or perhaps at all.
When you display the MAF gauge, you are looking at the unaltered value directly from the ECU.

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

The rain here finally stopped and I just went for a short low speed drive down to check on the boat house and the MAF 1 and 2 values ranged from .07 at idle to .55 coming back up the hill so there is a range being reported, but far below the 0 to 655 range listed in the UG manual.

No response yet from other UG users on the D1 forum, but I'll let you know if any come through. I also asked them to verify the protocol their UGs were using.

I am guessing from your replies that the difference in MAF values is too great for the MPG to be corrected with calibration? I have yet to find any resistance specs for the MAF to check its operation; is there a chance the ECU (or ECM as LR calls it) is reporting actual resistance values rather than g/s?

The output for MAF violates the OBDII standard. As such, there must be a defect somewhere, either in the MAF or in the ECU. We suspect the ECU.

Try the calibration.

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

I recieved this reply from a fellow who also has a 1998 Discovery 1 after posting my MAF readings of 0.07 to 0.55.

"Phil my ug is the 9141 on boot and I have the same maf readings as you, like I said if the ecm is reading the maf correct so the air fuel is correct in the engine but displays bad on the ug no biggie, but there is a chance the maf is being read incorrect which can be an issue. Since I did the fuel pressure regulator and injector upgrade I have had no codes and it runs normal/ smooth."

So the MAF values I am seeing appear to be normal for other 1998 Land Rover Discovery ECMs, not just my specific vehicle. Is there any other protocol that would provide different MAF reporting or a more accurate MPG result? Or is there a way to tell the UG to use a scaling factor of say 1000 to calculate MPG?

Your vehicle only supports 9141. The protocol is only the transport. The data transported will be the same regardless of protocol.

1. Perform the Fuel Cal
2. Look for an Firmware update.

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

Some additional information from a fellow on the Land Rover Discovery 1 forum. landroverforums.com/forum/discovery-i-39/how-test-mass-air-flow-sensor-69240/page2/

"Our trucks don't report the "A" element in the equation ((A*256)+B) / 100). A is always 0 on our trucks so it shows B /100. A and B are byte values returned from the ECU regarding the MAF sensor (took me a bit to figure this out) Each byte is a value between 0 and 256 so A appears to be an overflow for B's value? Basically we never get a raw value, we get the value the ECU reads and decides to give us. In theory they could be reporting cfm, or gpm, or who knows what.. would take a rover tech or engineer to determine this."

I replied:
According to Ultra gage support it is expecting Grams per Second (g/s) in values between 0 and 655; I'm seeing values between .06 and .61 read from the OBDII by both the UG and my Actron CP9580 code reader.

And he replied:
"Correct, because it is showing a value of 61 in the B variable, and being divided by 100 (61/100 = .61). The raw reading is 61, but I'm not sure this makes sense to still be in g/s. I believe the max range I saw was 122. still low for what our engine should be pulling."

This may make more sense to you than it does to me, but the apparent meaning is that the ECM is applying some scaling to the MAF values (dividing by 100?) but is not reporting the scaling(?) or not reporting in a way that UltraGage expects or understands. In any case I believe this exception should be added to the list on your web site of vehicles and functions that do not work correctly with the UltraGage.

I still plan to try calibrating the MPG, but have not yet driven far enough, given the low fuel usage values reported, for the UG to accept recalibration. I guess I need to re-fill the tank, zero the calibration, and take a long trip.

All that equation says is that the data is 16-bits wide. A*256 means move the A byte to the upper 8 bits.
So MAF= A,B = A[7:0],B[7:0]= AABB

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

Hi Folks,

I see that you have not listed a 98 Land Rover Discovery on your exceptions list yet. My issue with the OBDII reporting MAF values from .06 to .61 and the UG thinking it is getting 1500 MPG has never been resolved. I've tried to use the fuel calibration, but the UG still says I haven't used enough fuel to do a calibration, even after half a dozen tank refills.

I have never gotten a response from the nearest Land Rover dealer about your suggestion that they need to update my ECM, so I suspect there is not a solution there. You really need to add this to your exceptions list or update the UG to allow MAF value scaling which in this case apparently needs to be about 1000X.

Please advise.

The fuel calibration will automatically scale the MAF values. However, this will only work if the MAF values are actually MAF values that have been scaled by the vehicle......as opposed to nonsensical numbers that have no relation to the MAF. According to the result of Factory Test, your vehicle is not scaling the MAF parameter.

You are receiving that message because the fuel cal procedure is not correctly being followed (common), or its because the fuel calibration is so out that it reports too little fuel usage to calibrate. This is possible given your 1500MPG results. After step #4 below, place the Fuel Used gauge on the display and wait for it to reach >1.0 gallons. Once reached, Step #10 below should not display the message.

The dealer has no interest in updating your ECM as there is nothing for them to gain.

Fuel CAL procedure:
1. Fill up the fuel tank.
2. Set the ignition to the RUN position (Engine Off)
3. Press and hold the UP key to cause UltraGauge to recognize the fill-up
4. Zero the Average MPG. MENU --> Gauge/Page Menu .. --> Zero Ave MPG, G/H. (THIS TRULY STARTS THE PROCESS and Should not be executed again.)
5. Exit the Menu system (A MUST)
6. Drive until it’s time for the next fuel fill-up.
7. At the next fuel fill-up, fill the fuel tank and note the number of gallons/liters used (pumped). (Always use the same fuel
station and the same fuel pump)
8. Set the ignition to the RUN position (engine off)
9. Press and hold the UP key to cause UltraGauge to recognize the fill-up
10. Select MENU --> Vehicle Setup.. --> Calibration.. --> Calibrate MPG/Fuel, and change the value displayed to the amount
of fuel recorded in step #7. Press MENU when complete to set and save the calibration.
11. Exit the Menu system the cal is complete

Steps 6-9 if ignored will not impact the results. They are simply there because 6-9 are what are normally performed at fill-up.

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

OK, I have done what you suggested including zeroing the Ave MPG which apparently also zeroed the Gallons used. Since the UG had recorded just .31 gallons used in the last 600 miles, I will likely have to drive another 2000 miles before it will show > 1.0 gallon used. Are you sure that the MPG function will calibrate correctly if the UG says 1 gallon used and I have actually used 200 gallons?

I don't know that there is an update for my ECM or that the LR dealers have no interest in helping me because "there is nothing for them to gain" as you claim, but I do know that my new UG did not provide all the gages listed for my model and build date on your web site and that the 98 Land Rover Discovery model should be included in your exceptions list as I previously suggested.

I would suggest that you place the gauge in another vehicle, start the cal process. Once 1 gallon is reached. Switch it back to the 1st vehicle. Then set the gallons in step 10 from 1gal to 100gal. That should result in 1500mpg become 15MPG.
Once this is accomplished repeat the fuel cal in the 1st vehicle.

Best regards,

UltraGauge Support
www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time

Hi folks,

Two questions

1. I just bought a 2006 Jaguar Super V8 for my wife and as far as I can find it uses the same 9141 protocol as the 98 Land Rover Discovery. I want to buy a UG for it also and need to know if there is any advantage for the MX 1.3 for this vehicle or if the EM plus is the best choice.

2. I see there is still no exception listed for the 98 Land Rover Discovery regarding the fact that the engine management computer does not report fuel useage in the form that the UG expects but a much lower number and MPG is wildly high. I have tried to calibrate it and so far have a calibration figure of 110 just to get somewhere close to actual MPG, and it took a very long time to get the UG to think enough fuel had been used to allow calibration and a loooong time to run gallons used up enough to get close to the 110 calibration number. I believe this should be in your exceptions list and I hope the 2006 Jaguar Super V8 does not have the same problem.

As per the Ultragauge MX product page, the 9141 protocol does not allow access to manufacturer parameters. As such, the Ultragauge MX provides no benefit in a vehicle which uses the 9141 protocol.


Scanning our support ticket system, you are the only Land Rover user to ever report the calibration issue. Perhaps it is unique to the firmware used in your vehicle's computer.

Best regards,

UltraGauge Support
http://www.ultra-gauge.com
Support is available Monday, Wednesday and Friday, 9-5pm Central Time