So i have cleaned my TB and replaced the egr, iac valve and cleaned the MAF and replaced the spark plugs and air filter. According to my onboard computer i am getting at best 13MPG. is this right? for 6 cylinders i would think i would get a little better especially after hearing others with XJ8's getting 20 or better. I live in NYC so i know the gas mileage isnt going to be great but 13? anyone know where im coming from? can i trust the computer?

 

It is obviously easy enough to check the computer. As to the gas mileage, why not check it while out for a drive in the country?
And, opinions on this matter vary, and you have already received the alternate opinion from mine, but it is quite clear in the manual that a computer calibration of the TPS is required after TPS replacement in order to assure its correct operation. My gas mileage improved significantly after I did mine. As I said, other opinions are regularly offered. I happen to believe that the guy who wrote the manual MIGHT just know what he is talking about.

 

In computer we trust lol
Well, I do use computer calculations but I rely on USED FUEL part . Because sometimes it shows you have 0 range but you can go way beyond that 50 kilometers lol
Instant should be correct I can get 11.5 liter in other words should be in the neighbourhood of 15 MPG .

 

thanks for the response regent!

 

To be more specific, I bought my XJ6 when it had 130,000 miles. It gave 17-19 mpg on the trip computer, confirmed by tankful vs mileage, The car ran about that way until it had about 220,000 miles, 5 years later. I regularly check the fuel trims and lamda operation and I had issues during that entire time with the LTFT staying wound up at about 18%, the same as reported by others, but the car ran well and had no driveability issues. Then it started usiing more gas and the mileage dropped to about 13 to 15 and it began a transition stumble, like as it shifted gears. It then got progressively worse and began high idle. After lots of measurement, ISSC relacement, complete diagnostics for other sensors and lots of head scratching, I changed the entire throttle assembly and the high idle became constant rather than intermittent.

After I got an IDS, I did the throttle orientation and the lambda orientation, and nothing else, and the idle immediately settled, the LTFT began operating near -2 to +3 % with variation as you would expect, and the car began giving 19 to 21 mpg.

Those are the facts. Draw your own conclusion

 

good info Spark! I will definetly take it to the dealer and have the calibration done!

 

Whats TPS?? Can I do it?

 

TPS is your throttle position sensor, it is located under the throttle body. It measures the position of your throttle blade within the throttle body and tells the computer that position and the position of the gas pedal. You can do it, its not a big job it just involves several steps. Look up on the past threads, i explained it somewhere and if not me brutal or motorcarman has. gluck!

 

I've been consistently getting 19+ MPG until recently.

I've done two things: changed the oil from 20w50 to 10w40 and adjusted the (hex key) set screw for the throttle body. Since those changes, mileage has dropped to the low 16 MPG.

I figure the "set screw" change I made goofed things up. I've readjusted it again (back [close] to where it was) and I'm now in the 17+ MPG range. The reason I adjusted the set screw is because the idle was fluctuating between 1,000-1300 RPMs.

Anyway, I suspect you should be getting better than 13 MPG ...

 

I'm getting 9.6, but just did a reset and replaced trans last week, so I'll see what it is now.

 

I do a lot of highway driving and avoid the city at all costs. With cruise control being used constantly I average about 25-32MPG.

 

The mileage went to 13.7 city.

But I think it should still be higher.

 

I get about 21 MPG with my 95 XJR with mixed driving. Did a drive from Cali (390 miles) on one tank of gas so I am pleased with the MPG being that its from 95..

 

I have done this test twice and got the same result both times. I drive between 65 and 70 on a very non busy fairly level highway for about 15 miles on the way home. I reset the trip computer after I reach cruising speed. At the end of the test distance the trip computer reads 27 mpg. Just driving around town and average highway driving the ave mpg for a tank of gas is around 21 to 23 mpg. And this checks fairly well with the fuel used. Car has 114,000 miles on the clock.

EZDriver 95 XJ6 2000 XK8

 

In mostly city driving (sitting) in Los Angeles I was averaging about 14.

 

I'm interested to see V8 to V8 comparisons, not V6 to V8.

I'm at 11.5 to 12.5 city. V8 of course.

Thanks

 

But you're looking at a forum section dedicated to i6 motors.

 

all the better to cull out those bothersome V6-V8 comparisons, Plums!

lol...if I had to guess, I'd say Ant stumbled on to this one from the "New posts" thread from a mobile device where the actual forum it's in can be a bit of a mystery.

Ant, there is a similar thread over in the X308 (though less useful...it COULD be the X350, but I think not...) section I'm pretty sure and one member gives a link to some web-based data where he has logged 6 mo.or so of fuel purchases with mileage. You can probably find what you are looking for there.....but yours is either all stop-n-go driving or depressingly low for the model.

 

Yep, didn't realize it was the wrong forum.

sorry