I was thinking today about the fact that the Evolution stateside has been released and sold by Mitsubishi with the problem of ALL the cars sold running rich at various points in the high rev range.....

This obviously has been having detrimental effects on performance....with owners that use 93 octane reporting (myself included) a lack of power above 5000 rpm.

I understand that it has been said the reason for this apparent compromise in correct setup is that the car can be sold in California, where only 91 octane is available.

Well....thats fine for California...and people that do not mind a car that feels sluggish above 5000 rpm...but my questions are these;

1) Is this rich mixture contributing to the VERY HIGH gas consumption I am experiencing.....15-17MPG?

2) Will this rich mixture cause the catalytic converters early demise, if I choose to keep it?

3) Will there be further service issues that have been brought on by the rich mixture as the car gets older...i.e poor running at idle, more frequent replacement of expensive spark plugs, premature failiure of valve seats...ect.ect.......?

If this is the case, I feel Mitsubishi should step up to the plate, and rectify this marketing compromise....and not just develop cars to make it through the warranty period without any trouble

Any response??????

 

Exactly how did you arrive at this conclusion? And don't you see a solution (if, in fact this is a "problem")? Put a brick behind your accelerator pedal and the "problem" disappears.

 

Yes, they run pig rich.

No, leaning them out will not help gas mileage very much. I have an S-AFC, pulling fuel out from 4500RPM on up, and I still get maybe 16mpg... then again, the added power makes it much harder to keep my foot out of it...

 

Please provide at least a shred of evidence to support this assertion.

 

Where have you been the last month? Numerous posts have been made re: the Evo running rich.

Reference the numerous posted dyno graphs that include A/F ratio measurements. I.e the Visnu dyno graphs, the AMS graphs, etc. The Evo runs off the chart at 5500 RPM.

Also reference the exhaust tip of your evo - pitch black, a sure sign of a car running rich.

Also reference spark plugs. Pull your plug after a hard run and note the color.

The Evo _does_ run rich from the factory, ridiculously rich above 5500 RPM.

That's also why people are safely gaining ~35 HP with a simple AFC.

 

A few of the dyno tuners on this board have reported that the Evo runs very very rich at higher rpm levels. Shiv posted an A/F mixture graph in a thread in the past week.

I think it's silly that it is being considered a "problem" though. Mitsu made the fuel curve rich on purpose! Perhaps they were a little too conservative with the mixture in the high rpm's...but it is not a problem, per say. They, as a company have to tune their cars for the lowest common denominator. And thats 91 octane fuel.

If you are going to mod you car, I think this is exactly where you should start.(where 93 and 94 are available)


SC~

 

Agreed. Problem isn't the right word. "Tuning opportunity" or "opportunity for improvement", maybe.