Engine: D52447: Tuning Boxes types and MPG display

[tedm]

Just put a CarPerformanceParts tuning box on my '02 XC90.
I've noticed three things......

• firstly the car seems more eager than it was before
• Secondly, the tickover seems a little rougher which has a slight effect on the smoothness of the gearbox when you come to a gentle halt
• Lastly, the MPG display is now showing 36mpg over 4 x 6 mile (country road) round trips that I've done since the box went on. My overall consumption is about 27mpg. Is the box messing with the computer?

I need to take the box off again today as the car is going for a service so that will give me a chance to compare performance.

I also found out that the power can be increased or decreased by simply turning a 'knob' in the box. I presume this means it's a resistor type and not a remap which I'm guessing a cheap alternative. Are there any problems with this type of box?

I'm still undecided as to whether to keep it, but as it was pretty cheap (compared to a tank of fuel!) it's not really a problem.

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Having thought more about the fact that the car no longer comes to a smooth halt with the box attached I've decided to return it for a refund and look into my options a bit further.

[GSMGuy]

Do you have a link to the item?

If it was cheap, ie less than a couple of hundred... Chances are it isn't a "proper" digital device.... I would be wondering what parameters it is actually altering to get the increased power... A lot of the cheaper items simply fool the engine into running rich to put more fuel in.... this could affect our MPG display, but more info needed..

I have a powerklick type one on mine, idle is unaffected, and mpg readout seems as accurate (poor) as ever lol - but then I do now have just under 200bhp

Mike

[RoyMacDonald]

Originally Posted by GSMGuy

Do you have a link to the item?

If it was cheap, ie less than a couple of hundred... Chances are it isn't a "proper" digital device.... I would be wondering what parameters it is actually altering to get the increased power... A lot of the cheaper items simply fool the engine into running rich to put more fuel in.... this could affect our MPG display, but more info needed..

I have a powerklick type one on mine, idle is unaffected, and mpg readout seems as accurate (poor) as ever lol - but then I do now have just under 200bhp

Mike

Mike I've been comparing my actual mpg to the mpg readout and it varies from 4.2 mpg optimistic to 0.2 pessimistic. I wonder if it calculates like this...

Sit at lights for 1 hour use 10 galls - drive for 10 miles use 10 galls - calculation.... 20 gal to drive 10 miles = 2 gals per mile

Drive 10 miles use 10 gals - calculation.... 1 gal per mile.

That gives a 50% difference between the readouts.

I've used those figures to make it clear what may be happening. I noticed that I managed to avoid stopping at almost any traffic lights, with a bit of skill and a lot of luck, when I got the .02 reading, which is what made me think it must be using a calulation along those lines. Like my average speed calulation when I'm on the bike. I use the average speed final readout to estimate how my training is going so I try and avoid traffic lights as it includes the waiting time as part of the training session.

Roy

[gary austin]

hi ive used a plug in so called chip variable hp on my seat and it also shows a 15mpg increase on the mpg gauge but when you work it out it never changed from the normal 38mpg these devises tell the engine that the temp is cold so the air flow metre opens more as if it had just started and chucks in more air thus more torque totaly confusing the ecu but with no harm ive used one for 25k and the only thing i notice is that it smokes abit on stat up and when pulling away but whenm you remove the chip its ok no smoke better with a ecu remap rather than a plug in cheers gary