Talk about the tools we use to give GREAT mileage on engines.
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TOPIC: MAP Enhancer/modifier circuit

MAP Enhancer/modifier circuit 13 Feb 2020 12:31 #1

  • GregK
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For those of you who have seen me mention or advise including this mod on grooved vehicles that may not have seen gains to take more control of fuel delivery, you might've followed a link I included to an article explaining how to incorporate it.
Good news: the author of that article has joined the 21st century, started a YouTube Channel and is posting videos!

Dig into his channel - his aerodynamics mod videos are what I'm binging on since he popped up in my feed, but there is a TON of good stuff in there for us (like his EGR mod suggestions).

Here's the MAP:


In my case, I'm adding a wee tiny bit of voltage. You may need to subtract it, but this video shows how to do both. a good weapon to have in the arsenal you use to slay the dragon of big oil.
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Last edit: by GregK.

MAP Enhancer/modifier circuit 19 Feb 2020 20:59 #2

  • GregK
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Here's an update on my implementation of this circuit:

Because I'm adding voltage (as most of us who live below ~3000' elevation above sea level probably will), I've had to add a resistor to the +5VDC leg of this circuit before it connects to the potentiometer. why? Well, when I tried to trim just that wee bit more lean, I'd get an engine code (I never bothered checking it but I'm sure it has something to do with the MAP sensor), and the EGR valve would slam wide open causing the engine to stall. as best I can reckon, I'm knocking the 5V down to around 1V, which is still plenty of offset to add to the MAP signal, and I may be using maybe 0.3V of that. I'm not especially savvy when it comes to electronics, but I can probably find the right things to measure and formulas to plug those numbers into to get the REAL answer.

It is possible to get VERY lean with this circuit, In other words. This may have (well, probably has) something to with the EFIE I have on my o2 sensor as well. I'm still tweaking, so mileage is off my benchmarks, but it looks like when I'm in the zone, I'm getting slightly better mileage than I do when it's summer, and that's including some warm-up time (yes, I know it's bad...) BUT I think it's a bit too lean, because the power feels to have dropped off, and that could be a danger. I can now idle smoothly below 500 rpm...somewhere between 450-475 as it appears on my tachometer, whereas before it was a rough, stumbly idle

This is weird to report: I may have taken things too far. now I need to back off some, and find the happy medium between drivability and efficiency.
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MAP Enhancer/modifier circuit 24 Feb 2020 06:16 #3

  • GregK
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Another update here, for those of you tinkering along on your own rides.
The best procedure I’ve come up with for avoiding engine codes is to check the voltage the computer sends from the MAP at KOEO, flip over to the output of the pot and adjust to that voltage, THEN start the engine, wait for hot idle/closed loop, then tweak.
For me, there is a sweet spot, where the engine is simply and ridiculously smooth. And it always has been what I thought was smooth, but this puts a fine polish on that.
I’m still working on the balance between MAP and EFIE. But, mileage seems to be on a not insignificant uptick.
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Last edit: by GregK. Reason: Spelling
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