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Old 03-26-2008, 05:58 PM   #1
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Default Resource for engine management?

I'm familiar with basic stuff like timing, but when it comes to sensors, wideband vs. narrowband, and all the stuff related to tuning, I'm lost. My experience is mostly on old (pre smog) cars, and setting points isn't that useful a skill anymore.

Where is a good place to start to learn about all the things I need to know? I'm interested in learning the differences between piggyback controllers, standalones like MSPnP, and not only what they do, but why and how. Also, anything related to FPR's, BOV (beside Corky's book, which I will be getting), etc. Basics, nothing too complicated.

Books, websites or anyplace a noobie can learn somthing without having to ask a lot of stupid questions? Any suggestions?
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Old 03-26-2008, 06:01 PM   #2
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its a good thing we don't have a DIY TURBO FAQ.....or the link been thrown at you like 10 times today....
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Old 03-26-2008, 06:13 PM   #3
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Yeah, I read all that. Every single damn post. But while some of it is basic (what is a BOV), some of it gets into terms I don't understand. I know where the AFM is, but what I don't know, is what it does, and the benefits of eliminating it or not if I get a MS. I know I need to learn more, but where?

Just tried reading your writeup on MS, and it talks about stuff that I don't know. How do I know what to get, and where to start if I don't have the basic stuff down pat?
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Old 03-26-2008, 06:15 PM   #4
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maybe you could show up at the NE dyno day to try to pick brains and learn more
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Old 03-26-2008, 07:51 PM   #5
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Okay, maybe I'm just dense. Let me ask what I hope will be a semi-intelligent question, and go from there.

From Braineack's MS post:
Optional:
(1) MSPNP IAT Sensor Kit
Required sensor to remove the AFM/MAF

Okay, so you add a sensor to eliminate a sensor. Is the MAF that much of a restriction on airflow, and if so, why not just swap for a bigger one? I searched, and couldn't find a simple answer. Why would you want to do this? There has to be some other benefit, right? I'm not looking to squeeze every ounce of HP out of the car, but I do need it to be reliable, or I'm not going to enjoy it.

And another, in case that one wasn't dumb enough. The MS page lists three ways of installing it. Why wouldn't I just wire it in and be done with it? Do you have to switch back and forth between the stock and MS, or is that only for the smog inspection *****?
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Old 03-26-2008, 08:23 PM   #6
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If you know how a carb/distributor engine works, then you have 80% of what you need to know about fuel injection and electronic ignition. It's just a matter of replacing mechanical systems with electronic ones.

If you look into an engine control computer, it really breaks down to a timing map (distributor) and a fuel map (carb). They are literally just grids with numbers in them. The X axis is usually RPM, and the Y axis is some sort of load reference. A system with an air meter (AFM, MAF, whatever you want to call it...) will give the load in terms of grams of air per revolution. The air meter outputs a signal proportional to how much air is going through it. Various methods are used like flapper doors, hot-wires, and karman vortex generators, but they all result in an electrical signal that varies with airflow. Systems without air meters are considered speed-density. They use sensors that read manifold pressure and temprature to estimate the density of the air for load calculations. Now that the computer knows the load (air density) and engine speed (from crank and/or cam sensor) it simply looks up in the grid how much ignition timing and fuel it needs for that cycle. The ignition advance is referenced from the crank or cam trigger and the fuel injectors will deliver a known amount of fuel per millisecond that they are energized. All the other complicated stuff like accel enrichment, startup, overrun, emissions, etc... Can be easily explained if you grasp the basic concepts.

If you understand that, then ask some specific questions and I'll try to answer them. If on the other hand, that blew your mind then you might consider taking a class such as efi101. http://www.efi101.com, or reading a book on basic fuel injection systems.


If that's all clear to you, then
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Old 03-26-2008, 08:35 PM   #7
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Quote:
Originally Posted by rleete View Post
Okay, maybe I'm just dense. Let me ask what I hope will be a semi-intelligent question, and go from there.

From Braineack's MS post:
Optional:
(1) MSPNP IAT Sensor Kit
Required sensor to remove the AFM/MAF

Okay, so you add a sensor to eliminate a sensor. Is the MAF that much of a restriction on airflow, and if so, why not just swap for a bigger one? I searched, and couldn't find a simple answer. Why would you want to do this? There has to be some other benefit, right? I'm not looking to squeeze every ounce of HP out of the car, but I do need it to be reliable, or I'm not going to enjoy it.

And another, in case that one wasn't dumb enough. The MS page lists three ways of installing it. Why wouldn't I just wire it in and be done with it? Do you have to switch back and forth between the stock and MS, or is that only for the smog inspection *****?
Most standalone engine management systems use speed density because it's simple and they don't need to support a bazillion different types of mass-air sensors. Mass air compensates better for changes in volumetric efficiency of the engine, whereas speed-density will require recalibration when you make efficiency changes. Keeping the air meter means the factory computer can still work if you want to keep it for cost or emissions reasons. If you can go full standalone then just go speed-density and forget about the stock computer and futzing with the air meter.

Edit: Speaking Miata/Megasquirt specifically, I imagine that the MS is only using the temp sensor in the AFM for speed-density mode, and if you remove it (intake restriction) you need to provide it with another air temp reference.
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Old 03-26-2008, 08:43 PM   #8
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Thank you! That's exactly the kind of thing I wanted. Yes, I understood your post, but I want to learn all that "other complicated stuff". I not only want to read COP how to, but also the why of it (I understand the why of COP, that was just an example).

I know you can buy all sorts of stuff, from ECUs to sensors, but I want to know exactly what they do, and the benefits/drawbacks of each so I can make informed decisions about mods and purchases before I just dive in. I want to DIY as much as possible, but I also don't want to just make a mess of all of it. Right now the car is basically stock, and runs well. I'd like to keep that reliable driveability and get some more power. Hopefully, I'll learn something while I'm at it.

Oh, and to complete your last, cutoff sentence:
If that's all clear to you, then...what the hell are you asking us for? Do a search.

Edit: thanks again for answering my question. Again, the kind of info I want. So, is there a place to get all this in one place, other than asking a zillion questions?
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Old 03-26-2008, 09:37 PM   #9
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Quote:
Originally Posted by rleete View Post
...I know you can buy all sorts of stuff, from ECUs to sensors, but I want to know exactly what they do, and the benefits/drawbacks of each so I can make informed decisions about mods and purchases before I just dive in. I want to DIY as much as possible, but I also don't want to just make a mess of all of it. Right now the car is basically stock, and runs well. I'd like to keep that reliable driveability and get some more power. Hopefully, I'll learn something while I'm at it...
There's many ways to modify EFI systems. They range from cheap and dirty hacks to full-on replacement systems.

Let's take the example of adding more fuel. You can use tricks like cranking up the fuel pressure so that the injectors deliver more fuel for a given pulse, you can install a device that modifies signals to trick the ecu into delivering more fuel by messing with the sensors that it uses for it's calculations, or you can install a device that modifies the injector pulses directly. These are used when it's necessary to keep the factory ECU or when cost is the primary factor.

If you want to cut the bullshit, you either need to be able to access the factory ECU's program directly (Not really an option for Miatas), or replace it altogether with a programmable system (Megasquirt).
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Old 03-26-2008, 09:45 PM   #10
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Somewhere around here you'll find: DIY turbo stick, DIY MS stick, useful saved posts stick.
Then you can: search m.net, search mt.net, read the book "Maximum Boost" by Bell. That should hold you for a couple hours. Then go read the Megamanual and the V3.0 assembly guide. Another handful of hours there.
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Old 03-26-2008, 09:53 PM   #11
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The links in my signature are very helpful.
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Old 03-26-2008, 10:07 PM   #12
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Quote:
Originally Posted by rleete View Post
Thank you! That's exactly the kind of thing I wanted. Yes, I understood your post, but I want to learn all that "other complicated stuff". I not only want to read COP how to, but also the why of it (I understand the why of COP, that was just an example).

I know you can buy all sorts of stuff, from ECUs to sensors, but I want to know exactly what they do, and the benefits/drawbacks of each so I can make informed decisions about mods and purchases before I just dive in. I want to DIY as much as possible, but I also don't want to just make a mess of all of it. Right now the car is basically stock, and runs well. I'd like to keep that reliable driveability and get some more power. Hopefully, I'll learn something while I'm at it.

Oh, and to complete your last, cutoff sentence:
If that's all clear to you, then...what the hell are you asking us for? Do a search.

Edit: thanks again for answering my question. Again, the kind of info I want. So, is there a place to get all this in one place, other than asking a zillion questions?
Let me first thank you for asking the question and a special thanks to dammitbeavis for his answer You're batting 2 for 2!

I would suggest that you read the Megasquirt manual in this link: http://www.msextra.com/manuals/MS_Ex...ing_Manual.htm

I'm in your same boat. I also come from the 4 barrel carburetor generation.

Keep on asking questions; some of us also learn something when you do so.
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Old 03-26-2008, 10:09 PM   #13
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Quote:
Originally Posted by cjernigan View Post
The links in my signature are very helpful.
His links and also he is very helpful. Chad is always willing to assist
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