I have had very good luck with the Ultragauge scan tool with my 2000 XK8. But, with the 95 XJ6 there is an incompatability. Have been dealing with Ultragauge and they have been very helpful. It showed up with the miles per gal reading. The value was way, way out of reason. We have traced it to the mass air flow reading the scan tool is receiving. It is near zero. Since the tool uses this reading for computing mpg the mpg readout on the tool is way off. The mpg value on the trip computer in the car is right on. So it looks like to me and Ultragauge that there is a difference in the pin-out on the connector which causes an incompatiblility between the XJ6 and the Ultragauge. What else might be effected is unknown to me, but anything that uses the MAF value is definitely effected.

I would like a response from out experts on this subject as it looks like the ultragauge is at least incompatable in some areas on the XJ6 (X300) cars.

By the way the car runs fine and gets 27 mpg highway mileage according to the trip computer and fuel pump calculations.

If someone is buying the Ultragauge for use on these cars they would have a problem and should be made aware of it before hand.

EZDriver 95XJ6 2000 XK8

 

Most cars use injector pulse width to calc. Mpg

 

All x300 have a MAF reading that is wrong. I'm pretty sure it's 100 times less than it should be. Generally, an idle MAF will read 0.04-0.06 g/s on an x300. The real value should be 4-6 g/s.
Your scanner is probably working fine (and so is any other scanner that shows a 1/100th of an expected air flow rate). You just need to redo the calculations.

 

Thanks guys. Ultragauge does say that they use the MAF to compute fuel usuage.

But be that as it may the MAF reading I get is wrong as Straight6DOHC says it is. The ratio of about 100 is close to what I am seeing. In fact it is exactly the right ration according to the test I ran. I drove my XK8 with the gauge on at 45 miles per hour and got a MAF reading of 19 and a reading of 23 mpg. I then put it on the XJ6 and repeated the test at 45 miles per hour. I got a MAF reading of O.19 and 2400 mpg. Actually, that is amazing to have the numbers come out exactly off by a factor of 100. In fact the XJ6 does get a little better mileage than the XK8 and always has. Man that is amazing results.

Thanks Straight6DOHC for making my day. I never got that good of test results when I was in the flight test business.

Thanks guys