HERE IT IS.. HACKED S13 MAF

[crzycav86]

When I decided to turbo the ka, sr 370's was an obvious choice in the fuel department due to my budget setup. Another obvious choice was the hacked maf route to control the injectors. Unfortunately, no one that I know of has actually "hacked" their s13 maf. After looking carefully at the maf's design, I figured that rather than hacking the maf, and allowing unmetered air to flow through, I could somehow partially block air from going through the sensor, and tune the injectors that way.

The s13's maf is very different in design than the s14 maf. Besides being metal, the maf has its sensor secluded from the rest of the air. That is, the sensor takes a sample through a small port near the top of the maf, and then reintroduces the air into the main stream through two small channels. I decided to partially block the channels by threading two holes in which two bolts would be placed that enable manual alteration of the air flow through the sensor.

The benefit that this s13 hacked maf has over the s14 maf is that it allows tuning of the injectors by turning two bolts rather than getting a different ID pipe. It may even run injectors greater than 370cc with ease.(although I wouldn't try that at this stage... read on...)

Unfortunately, I could only manage to "tune" it with an a/f meter. I think I ended up blocking 75% of the channels(not 37% as you might think... it's the same concept as s14 hacked maf, but has different physics). I'll measure how much exactly I had to block later.

I do see some possible problems with the nature of the air flowing through it: I don't know if the airflow acts in a linear fashion at various velocities. For example, at under 3000rpm, the air may travel through the sensor as planned, but at higher engine speeds, the air may flow through the sensor disproportionately. It may run richer in the upper revs because the block-off mechanism may be less efficient.

The a/f gauge, and my perceptions say that the car runs the same as stock. It has no idle issues, it doesn't stall when I press the clutch, and the exhaust doesn't smell like gas. It will be tuned with my lm-1 after I finish the turbo install. We'll just have to wait and see how it ends up.

I'll try to get some pictures up tommorow to illustrate what I did. And I'll elaborate the process more precisely later.
Modified by crzycav86 at 9:53 PM 1/31/2005

[Warped]

glad to see its , hope it all works out for ya

[2d-ink]

Has anyone tried to use a 91 Maxima MAF? I have one I know the harness Plug is different but I can solder wires together just dont know if it'll work.. so Has anyone tried Maxima MAF?

Oh I tried searching nothing came up..

[Nismo_Freak]

Has anyone tried to use a 91 Maxima MAF? I have one I know the harness Plug is different but I can solder wires together just dont know if it'll work.. so Has anyone tried Maxima MAF?

Oh I tried searching nothing came up..

Using the Maxima MAF will not solve the issue.

[TrunkMonkey]

very good work crzycav. please make sure you keep us updated on what you find.

-demetrius

[crzycav86]

I finally got to take some pictures of it.

P.S: NICO members' rides rock! I'm using it to upload pictures from now on.. so easy!

This is where the air gets sucked through. Notice that the sensor part takes only a sample of the incoming air.

This is the other end of the maf. You can see where the "sampled" air returns to the main airstream through those ports... Now lets crack it open..

Here is an inside view of the ports with the cover removed. What I did was block these ports a bit to lean out the 370cc injectors.

Here's the cover with bolts, and the maf. This is a good picture to show how the bolts actually block the airflow that passes through the sensor.

Here's a pic that shows how easily it is to adjust. I just have to loosen the nuts(there's another one under the maf) and close/open the ports as necessary with a screwdriver.

I hope the pictures helped. More updates to come soon...

[crzycav86]

One more thing... There's a few more pictures of it in the member's rides section if anyone cares to check it out.

http://nissaninfiniticlub.net/...=9137

[Jookmasta]

so the myth is now a fact. its good to see that people on a tight budget may now have another option. keep us posted on the performance of it or if u run into any problems. seems like u may have found a cure but it isnt FDA approved yet. lol

[PapaSmurf2k3]

sounds like a cross-breed bastard child of a ECU controlled fuel injection unit and a carburator.

[KATwo40]

Hmmm, very interesting.

LM-1 = more than SAFC. I guess that doesn't matter if you're gonna have it dyno tuned, though. Pretty cool idea. If this works fine for you, I may toss the SAFC and hack the MAF til I can afford to go Enthalpy or Emanage.

Keep us posted!

[crzycav86]

Yeah. Considering the cost of an safc and dyno time would cost about the same price as the wideband, I opted to go with the wideband..

Not to mention this doesn't require much of an installation, and adjusting it is easy enough. A hacked maf can also support a bit more power than a stock one.

[Chezedik]

Cav, I have a question for you, or anybody else that would have a clue. What do you think about modifying the output signal via a resistor or something like that to hack it that way. Is this a possibility?

[crzycav86]

When the ideas of the hacked maf was originally being tossed around(on FA), the idea of a variable resistor was brought up. I think they said it wouldn't work because the voltage curve isn't linear. I think it went something like: The voltage from 2000-3000 rpm might have a voltage output of 1v-2v, while the voltage from 6000-7000 might give 4v-4.25v or something like that(those are just random numbers).

The debate was very in-depth, and so I didn't understand it too well. I'll try to find the original thread and post it. Or you can search on FA for it.

[:: orion ::]

GOod work on getting the S3 MAF to work with the 370s...we did something similar (but crudely, with duct tape) to lean out a friends car...worked great. We concluded that the % change or effect was NOT constant (i.e. it worked better up high, still quite rich in the mid range)...but it works...crudely.

...they said it wouldn't work because the voltage curve isn't linear.

Exactly. S-AFC has the tables or maps (VE tables?) built in, so it can modify the voltage vs RPM to make the changes appropriate and constant.

The key is that the voltage is a CURVE, not a linear relationship. Unless it's mapped out, you can't make a XX voltage change and see good results.

- Brian

[Chezedik]

So, I am not as familiar as I should be on the SAFC, but does it allow global correction, so that I may use injectors and intercept and change the signals to correct. That is to say can it be used to correct for injectors?

[Chezedik]

also, does it allow for dynamic timing changes?

[Nismo_Freak]

When the ideas of the hacked maf was originally being tossed around(on FA), the idea of a variable resistor was brought up. I think they said it wouldn't work because the voltage curve isn't linear. I think it went something like: The voltage from 2000-3000 rpm might have a voltage output of 1v-2v, while the voltage from 6000-7000 might give 4v-4.25v or something like that(those are just random numbers).

The debate was very in-depth, and so I didn't understand it too well. I'll try to find the original thread and post it. Or you can search on FA for it.

So you are using restriction of the vacuum signal to reduce the total amount of airflow through the metering unit? I forsee a little bit of a running issue when you go turbo, just my opinion though.

Fun project but I honestly see too much that can go wrong when an easy and proven solution is right around the corner for not much cash.

[crzycav86]

So you are using restriction of the vacuum signal to reduce the total amount of airflow through the metering unit? I forsee a little bit of a running issue when you go turbo, just my opinion though.

Fun project but I honestly see too much that can go wrong when an easy and proven solution is right around the corner for not much cash.

I also think that it might have some problems. If it doesn't tune well with the wideband, I'll invest in one of those australian-afc dealies.

[crzycav86]

Well, after finally nearing completion of the project, I have to give my review on the hacked s13 maf:

It's NO good.

You could adjust it so that it would get a mid 11-12 afr under boost.(good) but then you get a 10 afr at idle(bad)

You can adjust the bolts to almost fully block the ports, it can give a pretty solid 13-14 afr, but when reving the engine, the afr goes down to 12, and shoots up to 16-17. I don't even want to try testing it under boost.

I might test it a little more tommorow, but when my safcII comes in on friday, that will be the end of the hacked s13 maf.

I'm just glad the kat is running fine.

[side waz]

Ah that sucks dude, after all that work and testing just to have it not work is kinda demorilizing. I guess though it's better you found out this way though rather then having something go horribley wrong while boosting.

So it's probabley for the better. It was a hell of an idea though and keep tinkering as your theroy is totally sound. Keep us all posted.

Have a good one man.

[crzycav86]

It's no big deal. I saw it coming, but I just wanted to make sure I couldn't save the $250 for an safc. It wasn't too much work anyway, and it's not like the maf is ruined or anything... so that's good too.

[kingtal0n]

I just stumbled into this thread by accident from another forum and google searches. I was actually looking for parts... but I want to add something here. I am doing research on factory ECU tuning, using EEPROMS or FLASH ROMS and am currently working with a #62 ECU with a ZIF socket soldiered in place of the factory ROM. Up until I crashed the car, I had a running stock .BIN loaded with just the speed limiter and rev limit pulled back. My goal in the next few months is to open up the world of do-it-yourself factory ECU tuning to all the un-priveleged SR/KA/RB etc... owners who would like to tune their cars without using hacked mafs, piggybacks, or power FC's and expensive ROM tunes done by people in the business. Anyways, on with it...

The ecu that responds to maf voltage uses a non-linear graph to do A/F calculations. But you knew that. You should also know, then, that piggybacks like the SAFC have these non-linear curves built in.... The IN/OUT function in the SAFC emulates one graph, and converts it to another preprogrammed MAF voltage graph, such as S13 maf to Z32 maf translation. The Apexi unit, in particular, uses the same graphs in their power-FC stand-alone ECUs, its basically a direct copy of what you would find in the .BIN file of your factory ECU corrolating to the maf it responds to.

those graphs are free. you can download them for free from plenty of sites already. the cost to burn roms for your ECU is also VERY cheap, I paid $200 for all of my equipment, and I never intended to ROM tune the nissan ECU (i bought my equip for my thirdgen camaro's ecu). Even zif sockets and flash proms are nearly free for the price.

the main problem is people dont have access to a good well written instruction manual on how to tune the ECU and the only software currently available is hardly understandable. even I am afraid to toy with the poorly labelled rom tuner software in fear of blowing my motor due to ignorance. and now its even worse because I dont even have a 240SX anymore since my wreck on the 7th.... (hence the looking for parts, stumbled into your thread)

Besides all of that, getting back to the topic... Without direct ECU control anything else (hacked maf, SAFC, etc...) is just an accident waiting to happen. Even if you tell your SAFC you have a Z-32 maf, and provide corrections for your injectors etc... you are still running the factory ECU... and tricking the factory ECU means all your timing graphs are screwed up (have you ever seen the KA or SR timing graph?) completelly and one degree too much of timing and say goodbye to your expensive setup.

I say push for a rom tune, DIY style. Any information anyone is willing to share contact me [email protected] I will put you in touch with others willing to work together to find an overall solution to the DIY tuner situation and make factory ECU tunes as simple and cheap as they are for American car owners. We have a small but growing information data-base but the real funs just beginning. I am working with so far two other programmers on designing a ROM tune software in good logical english, similar to what Enthalpy(Scott) the god of ECU tunes uses for himself. With all due respect to him, he is by far the most amazing ROM tuner and anyone not interested in DIY should seek him out, but poor people like me have to resort to things like this.