Dear Oppo: Help with Mass Airflow modifications please

"Sally O'Broder" (KojiroT) 09/28/2014 at 14:05 • Filed to: Car Booze, Sensors, Mass Air Whatever, Math, Electronics, Honda E-RV, Honda C-RV, The Oven Conveyor Belt Has More Torque Than Your Honda

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Alright, so I haven't posted much about this, but I am dyscalculate. This is a learning disability where I have a huge problem with numbers and math. It is very roughly equivalent to dyslexia, only in broad strokes since math is everywhere blah blah high school teachers were right.

Anyway, naturally mass airflow stuff is hard math - none of this "number and direction of strokes for hiragana" or "how to tie a knot" soft stuff - and I could really, really use some help.

To be clear, this is specifically for the Honda CRV I'm converting to E85, and the knowledge and experience I gain from this will be applied later on to other projects in the future.

Most plug-in E85 conversion modules merely modify the mass airflow readouts. Some of the better ones might contain an added sensor or process these things in real time, but for my purposes I'm fine just clipping wires and soldering some things manually.

On top of that, I'm going to need to become more competent with this stuff if I'm going to do things like switch to larger throttle bodies and so on. Now is the time to get started.

I am going to manually advance the timing of my vehicle from the distributor. I have added a new air intake - pictures and proper Oppoprojects post forthcoming - and I justneed to richen the fuel mixture. I may or may not do some crazy injector swaps after my Ion gets on the road, but considering I need low-RPM performance and I will rarely hit WOT over the course of this particular tune I am making the call that the usual larger injectors will not be necessary. This is not a typical performance tune, this is an in-town delivery vehicle that occasionally has to go off pavement. I'm doing this for the fuel economy as well as for the practice.

Does anyone know what I need to do do change the signalling from the sensors, and can anyone boil it down into speech that is friendlier to my impairment? From my very rough understanding of this technology - please remember I'm used to working with OBDI cars and not this OBDII wizardry - all I need to do is intercept the voltage coming from whichever sensors my vehicle comes equipped with. My question is, intercept where, and how? Increased voltage? Decreased? Can I just stick a potentiometer on it and hope for the best?

Alternatively, can I just buy a new sensor that's been calibrated differently and stick it on there?

Arch Duke Maxyenko, Shit Talk Extraordinaire > Sally O'Broder 09/28/2014 at 14:11

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You shouldn't adjust the MAF, you tune the computer, and for that, you need a shop that knows what they're doing.

Sally O'Broder > Arch Duke Maxyenko, Shit Talk Extraordinaire 09/28/2014 at 14:17

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Apparently this year of Honda means I am 100% out of luck there. From what I've been reading, most people will either do an OBDI swap or the computer needs to have its processor desoldered, replaced with a socket, and then replaced with a programmable unit.

I can perform the soldering myself, that's no problem. Hell, I can even ease my way through the programming a teensy tiny bit, one parameter field at a time and with the help of an environmental tech who does these kinds of calculations every day. The issue is that this is a ton of expense that I cannot foot just to tune the computer, and the law of diminishing turns over into negative returns here.

Really, I can live with clipping some wires on a sensor and then replacing the sensor and taking it back to stock if I really, really have to.

Arch Duke Maxyenko, Shit Talk Extraordinaire > Sally O'Broder 09/28/2014 at 14:26

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The MAF works in conjunction with the TPS and the O2 sensor and then the computer runs calculations based on the output values of each to constantly adjust the air/fuel ratio between rich and lean. So, it's going to take a lot of trial and error to get the adjustment value right.

Sally O'Broder > Arch Duke Maxyenko, Shit Talk Extraordinaire 09/28/2014 at 14:33

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So...potentiometer, then?

Arch Duke Maxyenko, Shit Talk Extraordinaire > Sally O'Broder 09/28/2014 at 14:37

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Yeah, even then your going to want to hook up a computer to the system to monitor every thing until you get it right.

Sally O'Broder > Arch Duke Maxyenko, Shit Talk Extraordinaire 09/28/2014 at 14:38

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Oh yeah, I can certainly hook it up for monitoring; I just can't hook it up to perform any programming apparently I think.

sortofindian > Sally O'Broder 10/06/2014 at 19:43

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If you modify the inputs that much the computer will set a fuel trim error. I'm also guessing that your CR-V doesn't have a MAF sensor but a MAP sensor. Are you modifying to get less mileage? E85 on your stock engine is way less efficient than gasoline

Sally O'Broder > sortofindian 10/09/2014 at 14:59

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That would be why I'm not keeping my engine stock. The mileage on E85 can be fine if not better as long as you address the timing issues - 22 whopping degrees of advance should be able to do it for my engine.

The problem is, the "Local" Honda experts informed me that I'm going to have to do an OBD-I swap and buy some Hondata stuff if I don't do what I propose here and stick potentiometers on everything. Sucks to be a Honda owner, but adventure awaits!

sortofindian > Sally O'Broder 10/10/2014 at 21:19

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Are you raising the compression ratio of your engine? Otherwise you are wasting your time

Sally O'Broder > sortofindian 10/11/2014 at 00:20

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That's in the cards perhaps probably.

On top of that, there's the additional cleanliness of E85, which can save in terms of long-term maintenance.

Also, at the very least, this is educational.