Thread: Super MPGuino?
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Old 02-14-2010, 04:22 PM   #30 (permalink)
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Join Date: Jan 2010
Location: Newark, DE
Posts: 143

'91 CRX - '91 Honda CRX DX
90 day: 34.91 mpg (US)
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Originally Posted by gtkid2002 View Post
It has one single wire sender all right, but it also has two double wire senders right next to it.
The second one could be the radiator fan thermoswitch. I didn't think about it due to it's location on Civics/CRXs. The coolant temperature sensor and gauge sender are next to each other on the side of the cylinder head under the distributor, while the thermoswitch is on the back of the block or on the thermostat housing (depending on year).

Originally Posted by gtkid2002 View Post
For the TPS sensor, it could come in handy by using that as a factor when it could come to individual cylinder cutoffs. How much further the throttle has to be increased when you have say 2/4 cylinders cut off, how much this effects mpg, etc.
Or just to have a readout for the sake of constant-throttle driving.

Originally Posted by gtkid2002 View Post
I think the whole MAP sensor got explained to me once before, but it didn't stick long, because I forgot what that thing does again. If somebody wants to refresh my memory on it, that would be awesome.
It's simply a pressure sensor for the air in the intake manifold. The lower the pressure, the less air (and oxygen) gets pulled into the engine with each cylinder stroke. Oxygen is needed to burn fuel, so the ECU injects less fuel when the air pressure is lower.
As far as instrumentation goes, it's not much more useful than measuring throttle position, though it provides a little more information about engine load.

Originally Posted by gtkid2002 View Post
bobski - You mentioned you had a CRX, but have you ever done any work with Preludes? You sound like you know Honda's in general pretty well.
Not specifically, though I do tend to familiarize myself with the various models when I get a chance. Hondas go together like lego bricks, so I've used a few '88-91 Prelude parts on my CRX. Power window switches, front brake calipers (well, they're actually Integra calipers, but they're the same part), aluminum wheels and a 3540 brake proportioning valve before I converted to rear disks.
I've got sprinkling of parts from other models as well... Like I said, the '94 Integra gauge cluster, '90-93 Integra power mirrors, a D16Z6 and P28 ECU from a '94 Civic EX, auto->manual conversion using parts from a '90 Civic LX, the driver info center from an '89 Legend... The list goes on, and gradually lengthens (presently working on a '90-93 Accord climate control panel).
Honestly, that's one of the reasons I familiarize myself with other models... To figure out which of the goodies I can conceivably steal from junkyard cars and install in my CRX.

On topic, I started working on my own MPGuino variant a week or two ago. So far I've got '168 and '1280 Seeeduinos, 16x2 and 20x4 character displays, plus a 128x64 graphic LCD to play with. Really my goal is an MPGuino with nicer display capabilities -- a bigger display, maybe an LED bar graph/numerical display (either elevated ala late model Civic, or a HUD projector) and maybe some other stuff thrown in depending on how much I/O that leaves me.
The Arduino platform seems like a decent enough development environment, so I'm also working from scratch as a learning experience.

Originally Posted by dcb View Post
If it were pure arduino then it would probably be portable, but I found myself fighting with the arduino environment early on to get the guino to do what I knew the chip could do but that "pure" arduino couldn't due to space/performance/absent & changing functionality issues.
Old post, but anything specific you could share?

I've been playing with code to measure pulse length, but the output from my first attempt has been pretty jittery. The code just polls an input until it goes high, marks the time (according to millis), waits for the input to go low again and subtracts to get the duration. After trying out a 200Hz square wave, it became perfectly apparent I'm going to need to use micros at very least, and probably use an interrupt pin as the input.
Or is there a more hardware-centric method I should be using?

Last edited by bobski; 02-14-2010 at 04:52 PM..
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