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Thread: The Mega Supercharger 4AGZE thread, using twinscrew charger

  1. #331
    broken down ex guru Chief Engine Builder feral4mr2's Avatar
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    Default Re: The Mega Supercharger 4AGZE thread, using twinscrew charger

    Quote Originally Posted by trdee View Post
    god damn there's a lot happening in that engine bay johnny
    Yeah it's cool.

  2. #332
    Junior Member Backyard Mechanic jondee86's Avatar
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    Thumbs up Re: The Mega Supercharger 4AGZE thread, using twinscrew charger

    Yeah... when I see what you MR2 guys can cram under the hood, I get a bit embarrassed when I complain about not having enough room to put in a different type of bypass valve

    Cheers... jondee86

  3. #333
    broken down ex guru Chief Engine Builder feral4mr2's Avatar
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    Default Re: The Mega Supercharger 4AGZE thread, using twinscrew charger

    little project planned for later in the year...

  4. #334
    Junior Member Backyard Mechanic jondee86's Avatar
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    Thumbs up Re: The Mega Supercharger 4AGZE thread, using twinscrew charger

    After all the pissing about with the GFB bypass valve, I have finally kicked it into touch. Replaced it with this...



    That's the OEM bypass valve I grabbed off an old Subaru Legacy wagon at Pick-A-Part. Had to modify it a bit to fit in the same place as the Bosch/GFB valves. It's a two-chamber diaphragm valve with atmospheric pressure under the diaphragm and works as it should. Mechanically simple, inherently reliable, and enabled me to get rid of all the clutter I had with the GFB valve. OEM quality too

    And funnily enough, the annoying bang that I used to get every time I touched the gas pedal after being on the overrun has disappeared. Transitions into and out of boost are seamless. Now I just have to sort a misfire that happens straight after I hit the gas enthusiastically.... but my list is getting shorter.

    Cheers... jondee86

  5. #335
    Junior Member Backyard Mechanic jondee86's Avatar
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    Question Re: The Mega Supercharger 4AGZE thread, using twinscrew charger

    Been improving a few things... upgraded to 1NZ coils so running full sequential now. Also fitted some RC SL9-550 injectors as I was running out of IDC on the 440's. Been retuning the fuel map on the road and the engine is running pretty good. But I have an annoying misfire that I just can't pin down.

    Basically, you can feel it as a single "bump" when accelerating WOT in any gear Typically happens between 4500 and 5000rpm and apart from that one misfire the engine runs fine all the way to 8000rpm. It's not always at the same rpm, but to pick an example log data would be like...

    Load point: 173kPa @ 4800rpm
    AFR: 12.5 vs 12.1 target (still working on the fuel map)
    Ignition timing: 20.6 deg BTDC
    MAT: 55-65 degC depending on ambient
    W/M injection spraying

    I have now dropped the ignition timing to 17.0 deg BTDC at the same point and it has made no noticeable difference. Not to engine performance or to the misfire problem. Knock detection is not that useful due to excessive mechanical noise, so I can't really see if I am getting det or not.

    If anyone has any suggestions about possible cause/what to try next, post them up

    Cheers... jondee86

  6. #336
    Toymods Events Secretary Too Much Toyota trdee's Avatar
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    Default Re: The Mega Supercharger 4AGZE thread, using twinscrew charger

    hav you tried logging a run to see if any parameters are changing around there? do you have any engine protection/power cut settings that could be cutting in?
    1988 AW11 9A-GTE - project #1 | 1984 MA61 1JZ-GTE - project #2 | 1994 UZZ31 Soarer 1UZ-FZE - Cruise missile
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    .....and the within first laps everything that made the AW11 great hit Rex as if the 'Gods of driving fun' had all Jizzed on his face.....
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    Mono blocs mate....as close to yours as a Ferrari is to a Fiesta

  7. #337
    Junior Member Backyard Mechanic jondee86's Avatar
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    Default Re: The Mega Supercharger 4AGZE thread, using twinscrew charger

    I pretty much log every run when I am working on tuning the fuel map, and I have never been able to pick up anything that would account for the misfire. Seems to be load related as I don't have to be at WOT... anywhere around 50% TPS flows enough to get the boost up close enough to WOT levels. Just cruising around and getting on the gas for short bursts while staying below 5000rpm does not do it... I need to be making a decent longer pull to get the misfire.

    Doesn't matter if the AFR is rich or lean, still the same result. Stamp on the throttle or roll into it and the same result. I'm using heat range 8 plugs at the moment, but have used 7's and same result. Resistor plugs since that it what the internet says I should use with COP's.

    Actual ignition timing is likely 1 or 2 deg less than what I have in the ignition map, as I have a MAT compensation table set to start pulling timing above 60 degC. W/M injection follows IDC and starts spraying at about 14% IDC. I'll try pulling a couple more degrees out of it, but I would have expected to see some improvement before now if it was just a simple timing issue... worth a crack... easy stuff first

    Cheers... jondee86

  8. #338
    Junior Member Backyard Mechanic jondee86's Avatar
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    Default Re: The Mega Supercharger 4AGZE thread, using twinscrew charger

    So I'm now down to 15.4 deg (down from 20.6) BTDC at the 173kPa 4800rpm load point, and while the misfire does not seem so pronounced there is still something very minor happening in what is otherwise a pretty clean pull. But it is so minimal now that I shall stay with the timing map I have now until I can get it dynoed. Timing doesn't appear to be having much (any) effect on performance judging by butt dyno.

    Does 15.4 deg at that load point sound about right, or am I way off the mark ?

    Cheers... jondee86

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