Getting the most out of your Apexi S-AFC= Stock MAF honeycomb removal

[BlackStealth]

Originally posted by wizard
i did the mod, so far so good (1 week), gonna b pulling out the screw 2mmorow to add even more flow.

Just be sure to turn the screw, and not remove it completely. You don't want a hole in your MAF. You might want to add some silicone on the bottom to freeze it in place.

[BlackStealth]

Originally posted by JoeYu
Does doing the MAF hc removal mod do anything/effect the o2 readings? I have this mod done to my car and for some reason cant get the o2 sensor to read over .90 no matter what I set my afc settings to. I can lean it out fine and it reads lower values fine, but it's like i hit a cealing at .90 volts.

Strange. I can still get 1.00 volt out my O2 sensor. Try adding more fuel.

[wizard]

i get 1v quite easily.... dunno why you would have a problem with something like that, try turning the AFC up more and more...

[Bluv69k]

Originally posted by antero

You need more fuel across the entire RPM band. Try starting with 2% more fuel across the board on your low throttle settings. And if after a while they still haven't moved, add 2% across your WOT too. If your mid still stays at 139, add more fuel between 2000-3500 rpms.

Keep in mind, your fuel trims will probably require about 15-30 mins of driving before you'll notice any changes. A couple WOT runs usually helps too.

WOT, you mean high settings?
increased low settings 2% and lows dropped to 90
mid and high stayed the same. Should I adjust mid on high or low set?

[Bluv69k]

Originally posted by antero

An old incorrect theory. 50% increase actually works out to 720cc not 550cc.

More like a new wrong theory, Maybe the math works out but the combo dosn't. i used the s-afc and 680cc inj. Car ran like pure shit. -48 and still to rich, so much correction that the timing was 20-25 at idle. this cause knock in the upper 20's above 8psi. O2's wouldn't cycle and car had serious cruising issuses.
Apexi caters to hondas and rx7's. What is a 50% increase of those cars inj? Just because the math works dosn't mean the combo will.

[shofear]

I also feel that (at least in my car) 550's are close to the limit of an AFC/AFR. I'm at -38 in spots and still a bit rich, running 720cc's would be impossible for me without something in addition to the AFR.

[BlackStealth]

Originally posted by Bluv69k


WOT, you mean high settings?
increased low settings 2% and lows dropped to 90
mid and high stayed the same. Should I adjust mid on high or low set?

Yes. WOT = high settings.
Low trim=90 is not bad. It'll fluctuate alot. Just make sure it fluctuates near the 100 mark, and not the 139 and 70's mark. If you want, you could try reducing the fuel by 1% for idle in the low settings. This might bring you closer to 100.

Med trim=139 means not enough fuel. Add more fuel in both the low/high settings in the 2000-3500 range. If you were to log your O2 voltages, you'll see exactly which RPM range needs more fuel.

[TenchuStealthAssassin]

Wow, I should've read this thread sooner! Very informative stuff in here. Kudos to Innovator for bringing this subject up and all you guys who tested it out and gave accounts. Oh, and let's not forget Multiades' unwavering use of logic

JR.

[BlackStealth]

Update:

I've running on my spare MAF for the last two weeks. I had it tuned very well, but noticed the car got slower. Decided to check my trims, and mid fuel trim shot up to 139. No problem, I'll just retune. Turned the boost down and did my retuning. To my surprise, I'm having a hard time. I'll have it tuned fine for 0.75 bars of boost & zero knock, and then when I increment my boost to 0.80 bars of boost knock skyrockets to 18. Adding or subtracting fuel wouldn't get rid of the knock... strange... this is a first.

I give up. I don't have time to keep retuning the car now that I've enrolled into University. To save time I went back with my original MAF for peace of mind and disconnected the battery (reset ECU). Re-tuned, and no problems. I'm even back at 1.1 bars of boost with no knock..

My original MAF and spare MAF are both gutted (3 honeycombs removed). However, the mitsubishi part numbers differs. Ones from a 93 RT/TT, and the other a 92 VR4. My original MAF has the protrusion screw blocking the air stream, whereas the spare MAF doesn't (both came preset like that from the factory).

I'll keep ya posted if the original MAF does the same thing. I'm hoping not.

[Innovator]

Resetting the ecu is what brought your trims back to normal, no doubt. This mod makes the LTFT go a little wacky on the lower rpm ranges(1-3K)

I was warned by (imppoweronline) this mod would cause these symptoms, but it's still worth the trouble IMO. I just pull the BAT fuse for 30 seconds every few days. This resets the ecu without disconnecting the battery. By doing this, I keep the fuel trims and A/F ratio perfect across the RPM band at partial throttle, and powerful at WOT.

Some may say that it's not kosher to do that, but the extra thrust is worth the effort My engine feels happy, although it would be nice to be able to monitor knock. I don't feel any symptoms that would indicate high detonation levels, such as loss of power, shuttering, or high EGT's. Also, you would hear knock that was detremental from inside the car with the windows up. I've never been in a car that I couldn't hear detonating when it was detonating bad enough to potentialy cause damage. Even if your exhaust was loud, you'd still hear it.

My water injection almost completely supresses any *dangerous* knock that may occur anyway.