Getting the most out of your Apexi S-AFC= Stock MAF honeycomb removal - Page 29 - 3000GT/Stealth International Message Center

Jim Floyd · 08-31-2003, 04:16 PM

If the Hz level doesn't change dows that mean the timing doesn't advance ?

boostedVR4 · 09-01-2003, 05:37 AM

Quote:

Originally posted by Innovator
The HZ level have to change. They will be lower.

I have datalogs from before and after. There is no significant change in my HZ level.

BlackStealth · 09-01-2003, 06:32 AM

With the honeycombs in tact, my Hz readings was always clipped showing a maximum of 1607 Hz (maximum reading reported by a datalogger). Had to use injector duty cycle to imagine what the waveform would look like in the clipped region. The injector duty cycle would increase significantly inside the clipped region indicating a lot of air flow. Clipping started at 4438 rpms.

Now with the 3 honeycombs removed, the clipping doesn't always occur. And when it does clip, it's very brief starting at 5281 rpms. The duty cycle barely increases indicating air flow is a minimal increase above 1607 Hz.

So yes, there's definately a lower Hz level being reported back to the ECU when the 3 honeycombs are missing. The only way I can see that this mod wouldn't work, if one was to gut all 5 honeycombs.

Innovator · 09-01-2003, 08:22 AM

Quote:

Originally posted by boostedVR4

I have datalogs from before and after. There is no significant change in my HZ level.

Mine used to read up to 2850, and now after the mod, I see 2600 max.

Multiades · 09-01-2003, 10:19 AM

Quote:

Originally posted by Innovator
Mine used to read up to 2850, and now after the mod, I see 2600 max.

You're reading Karman Vortex frequency through the S-afc, not at the ECU. Obviously there will be a decrease at the stock MAS, but there will be no TOTAL DECREASE after the change at the MAS AND the change at the S-AFC (which, BTW, you can't read w/ the S-AFC).

A datalogger can pick up the change (because it only reads the values that the ECU is seeing), but there is always a cut-off at 1606hz, and you can't use a datalogger on your '95.

-Chris

wizard · 09-01-2003, 11:42 AM

the final HZ value is going to b the 1 you see on the pocketlogger...

the HZ value on the AFC will be lower b/c the karman is reading less air.
Thats why you have to add approximately 10% across the board.

at idle you have to add a LOT more fuel b/c the air just doesn't want to push its way through the honeycomb in the middle, unlike ad throttle, where it doesn't make too much difference.

The mod DOES work at adding more power to the car b/c of the better flowing MAS.
and it MIGHT even take away some of the timing, but it WONT b b/c of the HZ reading, it'll b b/c of something else.

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

boostedVR4 · 09-04-2003, 05:44 PM

Quote:

Originally posted by boostedVR4
Indeed, my HZ levels didn't change at all either. Has anyone tried the Greddy emanage? It has a timing control feature.

This entire timing advance problem is another reason why stand alone ECU's are becoming popular with our cars.

I need to correct myself. After reviewing some older data logs, I see my HZ levels were around 1550 to 1600. Now with the mod done, they are about 1450, to 1500. So about a 100 hz difference.

Bluv69k · 09-04-2003, 07:26 PM

Guys, I did this mod but havn't followed the thread much. My trims are a little high
low114
mid 139
high 119

Can I get some advice on how to get them down

BlackStealth · 09-05-2003, 06:02 AM

Quote:

Originally posted by Bluv69k
Guys, I did this mod but havn't followed the thread much. My trims are a little high
low114
mid 139
high 119

Can I get some advice on how to get them down

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.

JoeYu · 09-05-2003, 06:03 AM

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.

08-31-2003, 04:16 PM	#281 (permalink)
Jim Floyd Member in good standing Join Date: Feb 2001 Location: Lyons, CO Trader Rating: (4)	Inovator If the Hz level doesn't change dows that mean the timing doesn't advance ? __________________

09-01-2003, 11:42 AM	#286 (permalink)
wizard I drive, therefore I am. Join Date: Jun 2003 Location: Van Nuys, CA Drives: 92 Stealth TT Trader Rating: (1)	the final HZ value is going to b the 1 you see on the pocketlogger... the HZ value on the AFC will be lower b/c the karman is reading less air. Thats why you have to add approximately 10% across the board. at idle you have to add a LOT more fuel b/c the air just doesn't want to push its way through the honeycomb in the middle, unlike ad throttle, where it doesn't make too much difference. The mod DOES work at adding more power to the car b/c of the better flowing MAS. and it MIGHT even take away some of the timing, but it WONT b b/c of the HZ reading, it'll b b/c of something else. i did the mod, so far so good (1 week), gonna b pulling out the screw 2mmorow to add even more flow. __________________ Mods list: HKS 13g turbos, CC's FMIC, 550ccs Injectors, Walbro 341 high flow (hotwired) pump, Apexi SAFC-II, HKS EVC IV, MAF-T and LS6, Stillen Downpipe, gutted custom exhaust, Greddy Type S BOV, UR pulley, Resistorless NGK Copper plugs, Stillen drilled rotors, EBC red pads, steel braided brake lines, RPS MAX street clutch, Clarion TV/face, 1800watt amp/sub, infinity kappa speakers.

09-04-2003, 07:26 PM	#288 (permalink)
Bluv69k buy my car Join Date: Sep 2001 Location: Atlanta, GA Drives: I can't drive 55 Trader Rating: (8)	Guys, I did this mod but havn't followed the thread much. My trims are a little high low114 mid 139 high 119 Can I get some advice on how to get them down __________________ 2001 Lightning catz 9007 bi-xenon hids, CF radiator cover SOLD ! 1991 red VR4 New factory block( forged crank, forged rods), triple stack head gaskets, 3kgt stage 3 heads with oversized valves, ported lower intake, Big Bore throttle body and matched plenum, Fidenza cam gears, Ported and jet coated exhaust manifolds, jet coated DN precat eleminators, ATR downpipe with no main cat, custom catback, 3sx pulley, 650 turbos, DN Y-pipe, Rps stage 3 and fidenza flywheel, 99 lifters, SS brake lines, 18x9 snipers, drilled and slotted rotors, intrax springs, 3kgt short shifter, New leather, new carpet, Full apexi EL1 gauge setup, Blitz indiglo DSBC, Apexi BOV, supermac floormats and door sills, gto panel, ek2 rail mod, stillen intake, hot wire kit, Denso pump, S-AFC II, RC550 cc inj, aladdin a2000 remote start, push button start, reverse indiglo main cluster, greddy shift knob, sparco pedals, powdercoated plenum and valve cover, aluminum GTO plug plate, powdercoated aluminum dash vents, polished fuel rails, Hella H4 conversion, Hella 7500k Bi-xenon Hid kit. Hella fog lights with angel eyes and catz h3 bulbs

09-05-2003, 06:03 AM	#290 (permalink)
JoeYu Forum Member Join Date: Jan 2002 Location: Louisville Trader Rating: (18)	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. __________________ Click here to email me at hijoeyu (at) gmail (dot) com 1991 Midnight Blue Mitsubishi 3000GT-VR4, 3.1L GT PRO Stage III motor, Ported and clipped MJM 15g's (440 cfm each), 550cc Denso injectors, IPO Dual Feed fuel kit with SX Performance fuel pressure regulator and high flow fuel filter, Blitz DSBC Spec-R electronic boost controller, MAF Translator with Z06 MAS, Apexi S-AFC, MSD DIS-4 Ignition Control system, Accell Ignition coils and wires kit, DNP Y-Pipe, Bob Melton Downpipe and "Repair Section," Walboro Fuel pump, Optima yellow top battery, 10 Gauge fuel pump hotwire kit, fuel pump relay bypass, Autopower 4 point roll bar, RPS Stage II clutch, Greddy Type-S Blow off Valve, NGK Iridium spark plugs, EGR block offs, Carbon Fiber hood, Intrax lowering springs, TMO Datalogger, KVR Gas-Slotted Rotors, Krank Vent Kit w/ adapter, and etc...

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09-01-2003, 06:32 AM	#283 (permalink)
BlackStealth Verified Seller Join Date: Apr 2000 Drives: 93 RT/TT Trader Rating: (151)	With the honeycombs in tact, my Hz readings was always clipped showing a maximum of 1607 Hz (maximum reading reported by a datalogger). Had to use injector duty cycle to imagine what the waveform would look like in the clipped region. The injector duty cycle would increase significantly inside the clipped region indicating a lot of air flow. Clipping started at 4438 rpms. Now with the 3 honeycombs removed, the clipping doesn't always occur. And when it does clip, it's very brief starting at 5281 rpms. The duty cycle barely increases indicating air flow is a minimal increase above 1607 Hz. So yes, there's definately a lower Hz level being reported back to the ECU when the 3 honeycombs are missing. The only way I can see that this mod wouldn't work, if one was to gut all 5 honeycombs.