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Tuning With An Air/Fuel Gauge

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1 hour ago, chaseincats said:



7 hours ago, chaseincats said:

I thought the ecu (fuel injection brain if you don't want to call it that) was a bunch of microswitches on the s30s, no?

@madkawThat's an interesting idea with the afm sticking.  I don't want to switch the car to megasquirt because it runs fantastically 95% of the time especially after this tuning thread.

You must be thinking of old computer peripheral or I/O adapter cards, that use the microswitches to set up the port settings, card address, etc.

Edited by TomoHawk
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If you are interested in a less electronic way to tune the fuel injection, Autospeed.com has some good technical articles you read and try:  One uses an accelerometer in stead of the S-O-P  method.

BTW-  the accelerometer is also useful for determining shift points.


Edited by TomoHawk
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23 hours ago, Captain Obvious said:

So even though it might not be programmable, I DO think they are converting signals to "digital" and using ones and zeros derived from a highly accurate resonator circuit. It's much more accurate than an R-C time constant.

My post was basically a regurgitation of things I picked up from various other posts on the forum.  Odds are almost certain that you're correct.  My main point was that you can't really "tune" or adjust anything between the inputs and the outputs.  It's all hardwired/soldered in.

I did take the opportunity to dig up a neat article about the history of A/D conversion.  I think I've mentioned in the past that most of my electronics experience is just dendrites of knowledge taking me just far enough to solve a problem.  Many gaps.  Like a piece of Swiss cheese, it will support some weight but it's definitely not solid.  Kind of squishy. 


  • Haha 1
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It looks like you could only make changes to how the L-Jet ECU works if you had the original Bosch circuit diagrams and operation flowchart.  But at least you can fool around with small changes in the coolant sensor.

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  • 2 weeks later...
On 9/14/2021 at 6:45 AM, 240260280 said:

Only TVS is connected to the pedal.... look there

Is the TVS another name for the TPS?

Also, regarding the "sticking afm" would it be the resistance wiper that would be sticking or the air door inside the afm?

Edited by chaseincats
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