KA24E MAF is NOT the equivalent of CA MAF !!!

[biosehnsucht]

For the longest time, the belief that a KA-E MAF was as good as a CA MAF has been passed on from CA enthusiast to CA enthusiast, and perhaps in the general case nobody noticed any different (running too rich from overrunning the old tired stock FPR, or whatever else masking the issue.. leaking injectors etc).

However - the voltage to airflow curves are not the same! Yes, the both peak out at 190ish HP of airflow, but as you can see they are not the same :



This results in the combination of a KA MAF on a stock CA ECU (or a modified one where a stock CA MAF VQ table is still in use) creating a lean condition, always. Starts off just a fraction of a %, but quickly goes into several percent and towards the top end as much as 20% difference !

I copied the KA24E's VQ table out and then stuck it in the CA rom, and lo and behold! It runs so beautifully now. I used a hex editor to extract the data and save it as a Rom Editor style .bin file (like the other VQ .bins it comes with). Since you can't add new MAF types to RomEdit I just renamed one (in my case ps13_vq_map.bin) and then copied the KA24E one in its place, then used Rom Editor's built in MAF replace function.

Here is the KA24E MAF VQ map: hs13_vq_map.bin

I'm not posting a ready made ECU rom yet because I've not had the time to cook generic ones, I've just got my current DSM 450cc + KA MAF + etc bin.

[page02wrx]

Do you have AOL instant messenger? I have a few questions to ask you about MAF's and your 450 DSM injectors (I have the same injectors waiting to go in)

[biosehnsucht]

Click my name above my avatar ... if I'm unresponsive, its because I'm not actually at my computer (or playing a game or w/e), be patient and I'll get back to you.

[ch187]

wow thats scary. what should i do. i wired my KA maf because thats what i had the maf adapter for. i still have my ca maf but i think i may have tossed the plug. that blows what should i do? or is it nothing to worry about. what ecu do you have where you can cut and paste vq tabels? how do you edit your rom and ****?

[biosehnsucht]

I'm not going to give a tutorial for editing ROMs here. Search around, check out the ztechz forums (google it) .. etc. Not straightforward, unless you already have experience in similar fields of expertise. The usual software is Rom Editor, which you'll have to locate with google or one of the tuning forums (such as ztechz) as the official site is gone now..

However, if you know someone willing / able to socket your ECU and burn you a chip, you can get someone to make a rombin for you.

Here's a stock CA ECU rombin with KA24E MAF (untested):CA18DET-KA24E_MAF.bin

Here's a my current CA ECU rombin with KA24E MAF, DSM 450cc, raised rev limiters (7700/7400) and speed limit (240kmh):CA18DET-KA24E_MAF-DSM_450cc.bin

Edit: Disclaimer: I had my engine fully balanced when I rebuilt it. Don't assume because I have provided a rombin with raised rev limiters that its a good idea on your engine. Hell, I've never actually gotten the RPM that high and rarely close to it.. on stock turbo and cams there's not any power up there anyways.

[float_6969]

So how does the VQ map for the KAE compare to the SR's?

[biosehnsucht]

Well if I'm going to be doing more of these comparisons I'm going to go cook me a vq map .bin to CSV converter.. I'm not manually pulling out another 64 values!

[biosehnsucht]

Colors aren't necessarily the same in these..

These are unscientific ("max hp" is taken to be 190hp for KA (hs13) and CA (s13) and 220hp for SR (ps13)), but give you an idea.

Airflow as % of Voltage (5V, where 65535 = 5V, not corrected for peak VQ value or "max HP") vs VQ Offset:

Airflow as HP (based on "max HP" and peak VQ value) vs VQ Offset:

As you can see, the SR MAF goes quite a bit higher up in the HP range, but doesn't reach as high on the voltage curve, althought it's close. If you used the SR MAF on a stock CA ECU, I think it would also run lean.. looks like at "100HP" of air through the SR MAF the CA would read it as "80HP" or so because it will think it's a CA MAF.

[rico05]

I'm really glad that Bio found this out. According to him, his cold start issues are now non existant. I have a new EPROM on the way with the proper VQ table. Hopefully this will fix my drama!!

[Huffydmbcs42388]

so what maf can you use if your ca maf is blown? thats just about stock replacement?

[mbmbmb23]

Buy a CA MAF from someone on the board who has upgraded to something else, or....add an SAFC and use whatever MAF you want.

-m

[sideways danny]

the CA18ET uses the same MAF as the DET

[biosehnsucht]

I don't know if their voltage curves are the same, but the CA18DET and CA18ET MAFs are no the same.

The CA18DE USDM and CA18ET MAFs are the same however.

USDM CA18ET / CA18DE : 22680-61A00JDM CA18DET : 22680-58A10

According to JDM and USDM FAST, those MAFs aren't used on anything else, either.