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Just the facts please ...
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Discussion Starter · #1 · (Edited)
OK ... I did'nt want to jack Denniss thread for the turbo box and secondary injectors ... so I started this ... the beginning is here

The reason I'd like to use the turbo box is that it puts the ECU into open loop mode, which it has very little control of. Now I know that with my mods the stock ECU can handle it fine, but it wants to set the a/f to its specs, not mine. From the quick testing I've done it runs rich, but I want to lean this way out ... like to 15.5:1 - 16:1 to see what power there is and what mileage I can get from the car.

If I did that while it was in closed loop the ECU would adj the fuel trims to bring the a/f back to what it wants. If I used the turbo box to force the ECU into open loop mode, then my settings wouldn't be messed with ... right?:
 

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Super Moderator
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are you nuts? theres no reason to run that lean, even on N/A. the leanest I would EVER run is 15ish at cruising speeds for gas mileage.
 

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KDM to JDM.
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6,437 Posts
I had a teacher at LTI who had a kia rio that he installed a simple dial fuel tuner that altered the o2 signal on. He leaned out the motor until it would begin to misfire, and then step it back a notch. He was able to get over 45MPG out of the motor.
 

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be that as it may, I still don't think it to be wise
 

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Look up the "Lean Burn" systems. Elantras in Korea have it so I know our engine can do it, but our fuel here is wrong for it. They run uber-lean under no load conditions.
 

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Just the facts please ...
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Discussion Starter · #9 ·
Well, I was thinking , just for the tuning practice ... one map for the mileage and another for performance.

And using the turbo box, I can force it into open loop so the ECU won't fight the tune. Isn't this what the guys with the SAFC are having problems with?
 

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Eldiablo owner
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if you want to lean out hte car to get better fue leconomy i would wire up the smt-6 to the front O2 sensor wire
the nin the global setteing put the smt6 in low volt mode

what you would be doing is making hte ecu think the ecu is running richer then it is and it would lean it back for you
then as throttle and rev increases put more normal number in the analog (now 02 map)
 

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Just the facts please ...
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1,030 Posts
Discussion Starter · #11 ·
Right ... that makes more sense. But would you still be able to tune the fuel maps when you go into open loop mode (above 3000 rpm)? I thought it was an either or situation because there was only one analog output?

I'm using memory on this, but isn't there a section in the SMT6 documents that mention this? ... hmmm, that may be wrong ... but, yea.

But if thats true, don't you need the analog to tweak the MAF setting? If you used it for the o2 senor output, then you couldn't use it on the MAF. I understand the SMT7 does have two analog outputs which would allow this.

Hmmm ... am I thinking right on this :confused:

And just so you know ... I like thought experiments like this :rolleyes: so be nice guys, I may learn something ... lol
 

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Teach
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I mean I understand It's the THEORETICAL value for a perfect engine in a perfect atmosphere with no humidity at sea level...

But...

This is no perfect world. You need to TEST different ratios to see which one is the best for you.
People need to realize that 2 identical engines side by by side will need different fuel trims because the internals will vary slightly and how the engine burns fuel.
 

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^ I know what you're saying felix and I agree but my opinion is I wouldn't run that lean even for gas mileage. 15:1 is about the leanest I would go. Just my perference and thoughts. For WOT, no tuner AFAIK actually aims for 14.68:1. You usually run richer for safety margi and torque. (richer = more torque)
 

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Teach
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^ I know what you're saying felix and I agree but my opinion is I wouldn't run that lean even for gas mileage. 15:1 is about the leanest I would go. Just my perference and thoughts. For WOT, no tuner AFAIK actually aims for 14.68:1. You usually run richer for safety margi and torque. (richer = more torque)
Not always. Richer may lower the torque/power. Usually 12:1 is seen, but most of that is to prevent damage to the engine, i.e. pre ignition. With Bill's discussion about the fuel issues he had with his cam set, it is possible that going too low on the scale can foul plugs easier.

You can go with a higher fuel ratio, but ignition timing might have to be retarded a couple degrees for that same safety margin the extra fuel gives you.
 
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