The O2 isnt checked at WOT (open loop) so it shouldnt be an issue. Does this bucking occur only at WOT?
Have you added an aftermarket fuel pump yet? It is possible you are starving for fuel. Do you have an A/F gauge or EGT? What O2 voltages are you seeing at WOT? Whats the EGT in the top of 3rd?
Probably time you picked up an aftermarket pump if you havent already. Grab a Walbro 255HP Denso TT Supra or Cosmo pump. Id recommend the Denso unit (high capacity high pressure very quiet) but the Walbro is considerably cheaper...both are drop in. Either unit will get you into the 10s so I dont think youll need to worry about fuel delivery again for a while.
You can safely remove the lower and 2 side honeycombs as well as back out flush the adjustment screw in the bottom. That should stave off MAF overrun for a while. I hit fuel cut before ever seeing overrun (with the bottom and side honeycombs out). My Karhman counts were somewhere around 2250Hz which is (supposedly) at or past the max of the MAS. I had a correction factor of +38% at idle on the AFC to richen things back up...it wasnt near that bad at high RPMs and my car WOULD idle without a correction but my A/F Gauge wouldnt cycle like it was supposed to (the ECU fuel trim was too far off for it to compensate).
Before switching to the 2G MAS I added larger injectors and got rid of the fuel cut problems but my AFC was tuned like -30% at idle. After adding the 2G MAS my values are around -10% across the board for low throttle...not all that bad. I was hitting 1600Hz for Karhman when I initially switched to the 2G MAS and now Im hitting 1900Hz with a boost leak so I dont think the 1G MAS would made it this far without some serious hacking (and I still have ALL the honeycombs in the 2G MAS
). The 2G MAS is good for approx. 400-425HP before requiring modification so Im leaving all the honeycombs in for driveability (Jeff has left all of his in too without problems so far). Depends on what you are looking for...I found the 2G MAS for like $100 with wiring harness and turbo inlet piping. Youd also need a new 2G filter w/ adapter or 3KGT filter. If you plan on large injectors the 2G MAS compliments them very well (the 2G would drop in a 1G with 500-550 injectors WITH OUT any fuel control!).
Anyway...make sure you arent running lean first (might need a new pump). If you arent then probably MAF overrun so yank some honeycombs. Then next would probably be larger injectors.
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John
90 Talon TSi AWD
2KW K4U
