Fuel Economy Improvements.

[Turbo_Steve]

when i bought mine someone said to me" whats it like on fuel" reply when its empty i fill her up not even interested on mpg

When I lost my job and someone said to me "what will you do for money" replied when it runs out I lose the house, not even interested in saving money.




Dude, I am glad you're so wealthy you don't have to worry about saving money, but for the rest of us, if there's a cheap way of saving £50 a month on a tank of fuel, then I'm game.

[vr4-fan]

I feel mad with this situation , all you taken more 20 mpg I DONT UNDERSTANd , I going to move to UK , lol

[Turbo_Steve]

TBH Mate, I think it's a communication issue.

Are you sure your exhaust isn't leaking now?

[Fully]

TBH Mate, I think it's a communication issue.

Are you sure your exhaust isn't leaking now?

Lmao =)

I noticed a slight improvement with the bigger intercooler!

[Rambaud]

I feel mad with this situation , all you taken more 20 mpg I DONT UNDERSTANd , I going to move to UK , lol

Are you calculating in Imperial (UK) gallons or US gallons? The difference is ~ 24%.

[elnevio]

Are you calculating in Imperial (UK) gallons or US gallons? The difference is ~ 24%.

We've tried ascertaining this before, but to no avail. It would account for most of the 'difference', I think.

[big stan]

lets be honest here guys vr4 s are not good on juice period. they are set up rich from the factory and its really easy to be on boost. add to that transmission losses, weight and you will use the power, its a frugal driver who gets better than 25 mpg. On the other hand they must be the performance car bargain of the last 5 yrs, prices are so low at the moment its rude not to have one. If you want fuel economy buy a diesel, otherwise drive the vr4 with a big smile on your face knowing that 95% of the other drivers on the roads aint got a clue either what or how good they are. don t know about you but thats the way i like it., my 2p. stan

[elnevio]

To be fair, I keep an eye on my MPG for two reasons:

1) To detect any potential problems;
2) For a laugh!

[Wodjno]

To be fair, I keep an eye on my MPG for two reasons:

1) To detect any potential problems;
2) For a laugh!

Much the same, but 2) Cos i love Stats

[AlanDITD]

I filled up with 99ron on saturday night, went drag racing plus one or two other journeys of about 15 miles, i have about 1/4 tank left and i have barely done 80miles.

And i couldnt give a toss.

[fluffnik]

The MPG wouldn't be such a hassle if the tank wasn't so tiny and the gauge so, ermmm, poetic in its pronouncements...

[Dom B]

The MPG wouldn't be such a hassle if the tank wasn't so tiny and the gauge so, ermmm, poetic in its pronouncements...

Yeah whats that all about..... i thought the fuel gauge/sender makers were supposed correct for the shape of the fuel tank by winding the rheostat in the tank with a varying pitch to make up for the non linear shape of the fuel tank. So why does the tank go for almost 100miles on 1/2 to 1/4 but goes for 10 miles from 3/4 to 1/2. You have almost no idea how much fuel you have at any point in time until you fill up. Did the mitsi engineers really think that was good enough?

As for all the people saying "i just fill her up and don't give a crap" well that's not the point of this thread so go start another post entitled " i love to throw money down a drain" for everybody else this is a post to talk about the benefits and drawbacks of the design and see what can be done to modernise the consumption of the car and talk about pushing forward the design of anything and everything fuel economy hand in hand with performance related. Why?? because that is what this thread is about for the sheer interest of doing it, and so we can have more fuel left over from commuting to work for blatting!! and i guess so i can actually drive on a long journey without stopping 3 times to fill up and spend most of the journey planning where the next fuel stop is, then worrying when no petrol stations seem to be appearing. An M3 manages pretty good mpg with a hell of a lot more power so why cant we, surely the vr4 is superior!!!. Lets get the post back on track.

Out of interest did anyone see that repeat of top gear with the prius and M3 on the test track. The prius was flat out and the m3 just following at the same speed and guess what the german was more efficient on the mpg test.

[Turbo_Steve]

The simple truth is, unfortunately, that it's all in the software.
Well, maybe not the silly fuel gauge, but I'm kind of used to that now. LOL

But the two major factors for fuel consumption are the maps and the cars willingness to make boost.
A proper ECU change (a full reworking of the factory one, or a standalone) will allow sufficient control to improve the economy significantly.
Bigger turbos might help the early boost scenario.

You could use a decent ECU to have either a 2D or 3D boost control map.
For example, you could map TPS against RPM for more progressive boost delivery: keeping the wastegate bled unless throttle goes over 50%, for example. Will make the car a little more "binary" in terms of it's performance.
This will also allow a sensible curb in Throttle enrichment. Again, not sure what our newly flashed factory ECUs can offer there, but in terms of an Aftermarket, this would be simple enough to setup as either a 2D map, or potentially a more comprehensive 3D map, perhaps with TPS or load as vectors, or maybe RPM, as load would be another transient in a thorttle change. It's almost as though Mitsubishi didn't want to trust the MAF.

[miller]

An M3 manages pretty good mpg with a hell of a lot more power so why cant we, surely the vr4 is superior!!!. Lets get the post back on track.

and for that reason is why you see twenty M3's to your single VR4 on our roads today.

[Turbo_Steve]

that and the fact that they are newer. And German.

[big stan]

took mine to the lakes a couple of weeks ago. the round trip was 367 miles and i put a total of £68.00 of v power in. the gauge was showing just under halfway when i got home. the trip up was really steady around 60 mph following my mates van, but coming home i really got the boot down, not so much acceleration but mostly 90mph and a couple of blats at 110. the leggie seemed to do so much better on juice at the higher speeds . i may be wrong but i work that out at 24.4 mpg., and its more than i would have hoped for at the speeds travelled, the trip home from penrith just over 2 hrs. is it feasible that the leggie could be better on juice at the higher speeds/ or is it just another dodgy fuel gauge? stan

[elnevio]

You're right Stan, this has been observed before. Seems more fuel efficient with the 'progressive' driving!

[MarkSanne]

I've noticed the same!

A while back my wife put 10 liters of dieseasel in it before realising, then filled 'r up with 45 liters of 98 BP Ultimate, and drove 2 full tanks carefully, not boosting, very, very low revvs and still it was just as 'bad' in using fuel as when we boot it. The trip I recently made in the UK where I booted it all the way was delivering a fair deal MORE mpg!! Seems there should be something to look into when the ECU gets flashed As most know these cars run very rich, most of the time without any need for that much fuel.

[vr4-fan]

I've noticed the same!

A while back my wife put 10 liters of dieseasel in it before realising, then filled 'r up with 45 liters of 98 BP Ultimate, and drove 2 full tanks carefully, not boosting, very, very low revvs and still it was just as 'bad' in using fuel as when we boot it. The trip I recently made in the UK where I booted it all the way was delivering a fair deal MORE mpg!! Seems there should be something to look into when the ECU gets flashed As most know these cars run very rich, most of the time without any need for that much fuel.

buy a SAFC , and tuned for not too rich for drive dialy , and the weekend other setup

[Turbo_Steve]

SAFC won't make any difference for regular driving as the ECU will correct back to lambda target: only WOT will really be affected by an SAFC....and that isn't the problem area. I'm absoloutely convinced it's partial throttle enrichment that's the culprit here. I'd be interested to see whether those using cruise control get better MPG, as it uses significantly less throttle correction. Another test would be to "clamp" the throttle on a car: limit the throttle opening so that the mechanism will not go past 50%. Then go for a drive, and sit on the "limiter": I'll wager the economy is waaay better.
Another test would be to to wire the wastgates open. I'd be certain that this will not make much difference to economy, but it WILL prove that it's TPS based throttle delta and not load based enrichment that's the issue.

The other thing worth considering is the temperature that this engine runs at: it's a hottie, and I'm not sure why: but I AM sure that the richness of the fuelling on boost is trying to keep the bores cool. Water Injection is probably the quickest fix here, but it would be preferable to establish why there is such a heat build up. The rear turbo seems to be a big source of trapped heat. Either lagging it, or perhaps fitting an independant oil cooler would be beneficial. I'm guessing though: heat dispersal can be a nightmare.