Two questions

[Mitspowered]

OK smart people collective. I had asked these questions before, but no one answered. I thought I'd try again in it's own separate thread.

I am kicking around the idea of doing some light modifications to my smart car. Nothing major and (hopefully) nothing damaging.

I'm operating on the theory, that his car (like most) runs a little rich from the factory. Although I imagine eventually someone will crack the ECU code and offer options to modify fueling that way, in the meantime I am considering doing it the old fashioned (well to modern MPI cars) way-reading A/F by an O2 sensor and guage and modifing the percieved air coming into the engine, and thus lower the injector cycle via a fuel controller (S-AFC II in my case) for a slightly leaner condition.

Whether or not this will work- I believe the smart uses a MAP sensor, rather than the Karman-vortex type MAF that I'm accustomed to- remains to be seen. Hondas, at least in the late 80's and 90's used MAP sensors, and some (specialized versions at one time) S-AFCs were used on them.

So my questions are as follows:
1. Is anyone from the VW/Audi/ Mercedies/BMW world familar with a "patch "type harness for those cars? The last thing I want to do is hack up my smart's engine harnes to interpret and modify an airflow signal. In case you're wondering what a "patch harness" looks like-here are a couple of examples:
http://www.boomslang.us/safc.htm
http://www.autosportwiring.com/

2. Would anyone happen to know if our existing O2 sensors are WB or NB? I have no idea which cars are running WB O2s (in fact my knowledge ends at some 90's era HX or something Civic), but the one in my kit is a Bosh and well you know...

All answers and comments would be appreciated-infact I might not attempt anything without a little more knowledge than what I have now.

Thanks!

[Dave777]

What if your "theory, that his car (like most) runs a little rich from the factory" is wrong?

Could it be it's the highest MPG rated gas-powered car sold in the country because it's already properly coded for maximum economy?

Good luck. Let us know how it goes.

[Mitspowered]

Originally Posted by Dave777

What if your "theory, that his car (like most) runs a little rich from the factory" is wrong?

Could it be it's the highest MPG rated gas-powered car sold in the country because it's already properly coded for maximum economy?

Good luck. Let us know how it goes.

You make a good point, Dave777. The WB sensor will help to tell that tale.

I am curious if you have any opinion or comment about the 90's era Geo Metro-similar weight and drivetrain, but significantly higher (~20%) fuel efficency. I have to confess I haven't looked too deeply into this, but I am just looking to start a bit of a discussion.

[Dave777]

I know virtually nothing about sensors, mapping, ECUs or the like, but I'm almost certain a 90's era Geo Metro would not pass today's emissions standards or crash standards, so it's a moot point, as far as I'm concerned.

[Fredvon4]

Mits... I have an enormous amount of experience in these issues but admit no car yet and this will be very first MB/Mitsu variant...

That said, I suggest a back to basics approach first...

warm motor...new properly gapped plugs.... full acceleration up to 3rd or 4th gear... kill motor..... coast to stop...pull each plug and see the rich or lean evidence

I suspect guys like you and I will have to experiment for a year or so before we have the true electron geeks bring the re-mapping software over here.

There is quite a bit of potential in this motor but I am somewhat intimidated with the stupid automated manual tranny... I would dearly like to divorce the motor management from the tranny management loop.

[BobbyBRD]

the smart's factory setting makes it run rich when bought new. the ecu then adapts to your driving habbit. this process is intensified in turbo models.

@mitspowered. try to contact a euro tuner. they pretty much all speak english. they allready sell the 71 to 84 hp tune.

Bobby

[torqueaholic]

The SFAC WILL help your car no matter what.

You will be able to tune your specific vehicle to the way YOU like it. Not the way that Smart was forced to by CARB (CAlifornia Resources Board) or by US government regulations.

Of course, any other engine mods you do to it like exhaust, intake, etc, you will be able to optimize for those changes.

[torqueaholic]

As a side note, one of the reasons the Thorley exhaust made good power is that it very likely leaned out the AF ratio.

[jwight]

Have to ask the two posters above:

BobbyBRD - has this been measured, confirmed by smart or is it just anecdotal? Not meant as a slam, just want to see where the original info was found.

torqueaholic, very likely leaned out the AF ratio? Best guess or based on some sort of scan results? Again, not meant as a slam but an awful lot of speculation goes on here, most of it backed up by....not much. Maybe the DTH guys can comment on their power gain vs. AF ratio at some point.

[xcrew229x]

The car's computer can compensate for the more freely breathing exhaust, or intake, to a point. Once you exceed the parameters of the computer mapping, it's hard to say if performance will be better or worse without a remap. I had a Blazer with a massive manifold vacuum leak that still passed Ohio's E-check due to the computer's ability to compensate for the leak. Just for info.......