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Thread: Autronic SMC boost control help

  1. #1
    Forum Sponsor Carport Converter TurboRA28's Avatar
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    Default Autronic SMC boost control help

    Hello, is anyone running an Autronic SMC and using the Autronic boost control valve?

    I've found a few different methods for setting these up and totally confused. I've currently got it connected as suggested on the Autronic website

    http://www.autronic.com/technical_da...veExternal.pdf

    This explains the plumbing and mode flags. But doesn't give much detail at all really on how to set it up in the tune.

    But this isn't working right. Ive set the boost limit at 190kpa. But it just keeps boosting until the boost cut comes in.

    So something is not quite right.. Hoping someone has some experience setting these up before?

    Thanks
    Joel
    1977 RA28 Celica - 1MZ-FE Members Rides
    1996 FZJ80 Landcruiser.
    Email : [email protected]

  2. #2
    i wrote the Automotive Encyclopaedia roadsailing's Avatar
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    Default Re: Autronic SMC boost control help

    you know 190 kPa is around 22.5 PSI right? do they say to set it as gauge pressure or absolute pressure?

    what is the boost cut set at? try setting it to 90 kPa and see what happens
    like to drift? live in victoria?
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    formerly shinybluesteel

  3. #3
    Forum Sponsor Carport Converter TurboRA28's Avatar
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    Default Re: Autronic SMC boost control help

    Howdy, its absolute pressure, so I figure 190 would be around 14psi or so.

    Well the whole boost cut/maximum boost seems to be the same thing.

    You set the max boost, then set how many kpa over max boost before it cuts injectors.

    So I have max boost at 190kpa, then 20kpa overboost for 2seconds before the cut.

    If I understand it correctly that is!
    1977 RA28 Celica - 1MZ-FE Members Rides
    1996 FZJ80 Landcruiser.
    Email : [email protected]

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    Toymods Vice President Chief Engine Builder TheToyman75's Avatar
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    Default Re: Autronic SMC boost control help

    Joel,

    Call Jim at SAS on Monday mate and let him know you got your BCV from me/SAS if he knows your a customer of ours he will help you out.

    The "Autronic" website isnt actually owned or run by Autonic so its not the most reliable source of information.

    I'm off for 2 weeks but Jim will be able to answer that any time after his morning Cigarette
    1971 2T-B Celica TA22 ST.
    1973 2T-G Celica TA22, aka "The Unicorn".
    1975 2T-G Celica TA27 GT
    1976 2T-G Celica TA23, aka "The Colonel".
    1985 3F Auto FJ62 Landcruiser
    1989 7M-GTE MA70 Supra, aka "The Poopra"

    History: Rods Classic Celica Sampler thread.

  5. #5
    Junior Member Backyard Mechanic 1jzracing's Avatar
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    Default Re: Autronic SMC boost control help

    i had a little trouble with my exact same unit, the conections are right on the picture and need to be checked carefully, you need to make sure the little controll valve is connected so that the line from the manifold/turbo outlet and T is on the normally closed port and the port from the back of the gate is open to air through the valve

    the smc opens the valve on start up and to controll boost it starts to close it, that way if anything fails the valve will close and boost will revert back to the gate spring

    also i just set my over boost limit a bit higher till it didnt hit it

  6. #6
    Junior Member Backyard Mechanic 1jzracing's Avatar
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    Default Re: Autronic SMC boost control help

    PS how big is the spring on your waste gate??

    mine sees about 15psi with no controll valve at all so boost cant be set at anything lower than that

  7. #7
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    Default Re: Autronic SMC boost control help

    Howdy, thanks Rod for the offer to give Jim a call. Must be busy down there, have tried a couple of times but no luck.

    1jz, thanks for that info. Its a 38mm tial wastegate with a 7.5 or so psi spring.

    I've made some progress though...

    It's all plumbed up correctly at least.

    I disconnected the power wires to the valve, boost was the wastegate springs value.. I was seeing around 160kpa (absolute) manifold pressure on the logger.

    I then connected the valve and can actually hear it click (hope thats normal?). Guess its just closing.

    I then set the boost point to 170kpa. Not sure why, but for some reason the average kpa after looking at the logs was around 185kpa.

    I then upped the boost point to 220kpa. This time the average boost seems to be more like 210kpa. When looking at the logs, the boost set point you can see is 220, but the boost valve position is varies from 60 - 30%.

    So for example boost is 214kpa, valve is 50%. Then 219kpa, valve is 30%. Then it drops back down to 218kpa, valve 45% then 213kpa, valve is 60%. Kinda cycles like that.

    Its like it sees that its almost at the set valve (220) and opens the valve up a bit too much and ends up back down 10kpa, then starts building up again and so forth.

    Maybe this is acceptable?

    Cheers
    Joel
    1977 RA28 Celica - 1MZ-FE Members Rides
    1996 FZJ80 Landcruiser.
    Email : [email protected]

  8. #8
    Junior Member Backyard Mechanic 1jzracing's Avatar
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    Default Re: Autronic SMC boost control help

    thats much like mine does, when i set it low it over boosts, and when i set it high it under boosts,

    i would be very intertested to see what you find out as ive been chasing this for a while and have never got it to read quite right

    there is a setting called boost offset and it adjusts boost to match the set point but i cant seem to get this to make much difference

    I also cant get it to go past 260kpa (23psi) no matter what i set anything to this is very frustrating because i should be able to run 25-26psi

    ps. I tyhink the valve percentage opening is not really of much relevance as the waste gate will be open different amounts at different rpm and throttle opening, it will cycle up and down a slight amount as it controlles boost, im assuming its a closed loop type of system that reads and reacts
    Last edited by 1jzracing; 16-08-2006 at 09:37 PM.

  9. #9
    Forum Sponsor Carport Converter TurboRA28's Avatar
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    Default Re: Autronic SMC boost control help

    Some info from another forum that someone has been helping me with , quite good info so thought i'd paste it here -

    You are getting somewhere now. With 160kpa wastegate boost and 170 kpa target you would expect average boost to be higher than 170 with 0's in the Control Range Offset (CRO) table. This is because your target is very close to the wastegate base pressure and you would only want to apply a disproportionally small pressure to the closing side to achieve the target. But the ecu doesn't know how close the target is to the wastegate base pressure. By putting values in the CRO table you are effectively telling the ecu to correct for physical constraints of the setup. In this case you would use -ve values to start the boost control valve earlier.

    If you wanted a 250kpa target with a 160kpa wastegate, ie 150kpa boost with a 60kpa spring, you will have to put largish +ve values in the CRO table because the wastegate is going to need a lot of help to achieve that boost.

    With your target at 220kpa your log shows 213 to 219kpa which would suggest about +6 is required in the CRO to achieve 220kpa. There are different rpm sites in that table so you can correct the offsets as the turbo comes in and out of its best efficiency rpms.

    Don't worry too much about the logged valve position, the main thing is how stable the boost is. If the line looks a bit nervous (jumpy) try increasing the Boost Control Range by 25kpa or reduce the Dynamic Comp. If it sags or bulges but looks smooth then that is fixed with the CRO table.
    1977 RA28 Celica - 1MZ-FE Members Rides
    1996 FZJ80 Landcruiser.
    Email : [email protected]

  10. #10
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    Default Re: Autronic SMC boost control help

    Some more really good info -

    If you haven't reached information overload here is a bit more.

    I think the "formula" in the user manual to calculate the Boost Control Range is
    bizarre, the BCR is how many kpa of manifold pressure you want to control the
    valve over, not some relationship between target and base pressures.

    Example 1, target = 250 kpa, BCR = 100, CRO = 0 (no offset).
    The boost valve will operate over a 100kpa range centered on the target boost.
    It will be hard on (100% duty cycle trying to make boost) if the manifold
    pressure is below 200kpa (half the control range below the target). At 200kpa it
    will start to pulse to allow the wastegate to open easier as it is coming in
    range of the target boost. At 250kpa the valve is theoretically in the midpoint
    of its control range (at 50% duty cycle). If the manifold goes over 250kpa the
    valve will proportionally increase until it is full off at 300kpa (half the
    control range above the target) trying to reduce the boost.

    Example 2, target = 250, BCR = 50, CRO = 0
    The control range is half the above example, this means the valve will be at
    100% duty cycle until the manifold reaches 225 kpa, still 50% at 250kpa, but 0 %
    by 275kpa. Compared to above the boost might build a bit quicker because you are
    delaying the opening of the wastegate until a higher manifold pressure, but the
    boost will probably flucuate wildly. This will happen because the wastegate
    mightn't be able to bleed enough boost quickly enough and then when it
    overshoots it will apply too much bleed as the valve is turning off completely
    at a lower overall manifold pressure.

    If you make the BCR too large it will start to bleed the wastegate at a low
    manifold pressure which will mean it will be slower to build boost but once it
    makes the target it may overshoot because it will also not apply full bleed
    until a higher manifold pressure.

    You of course can try to speed things up by increasing the Dynamic Compensation
    parameter but you run the risk of making the boost oscillate, especially with
    larger area wastegates.

    The Boost Control Range Offset (CRO) parameter is used to correct boost that is
    stable but either side of the target. With example 1 if you had a CRO of +20kpa
    with the other settings the same as previous this will maintain the valve at
    100% until 220kpa (200+20) and won't go to 0% until 320kpa. You might have to do
    this as you go higher in rpm because the turbo might be running out of
    efficiency or else the exhaust back pressure might be increasing which will
    cause the wastegate to lift off its seat easier. As with your 170kpa target test
    you would have to make the CRO negative to achieve the target as you have set it
    very close to wastegate pressure.

    The wastegate area increases by the square of the radius (because they are
    generally circular) and it has the back pressure in the exhaust manifold trying
    to lift it off its seat. If you go from a 32mm wastegate to 40mm you have
    increased the surface area about 56% which means the wastegate is much more
    susceptable to changes in exhaust back pressure. So a slight change in the boost
    valve duty cycle will have a much greater effect on the 40mm wastegate than the
    32mm one. This can be where you start tearing your hair out trying to get stable
    boost at all rpms. You can start putting restrictor jets in hoses to try to
    soften the wastegate response but you have to think about where you put the jet.
    If you put it in the actuator line after the boost valve you wil affect both the
    pressurisation and depressurisation of the actuator, if you put it in the
    pressure line before the boost valve you will affect the pressurisation of the
    actuator only, conversly if you put it in the vent port of the valve.

    As a general summary, don't use too big a wastegate, start with CRO's = 0, start
    with a low Dynamic Comp (0 or 1), set your target, trim the CRO -ve in coarse
    increments if generally exceeding target, get the boost stable (might have to
    experiment a bit with BCR and DC), then trim the CRO finely. If all else fails
    consider restrictor jets (maybe the boost valve is too big for the actuator). If
    you can't get it stable at all check that the MAP sensor reading is stable by
    disabling the boost control and just run on wastegate pressure. If the MAP
    sensor reading is unstable you will never get the boost control stable because
    of phase (time) delays in the various elements. If the MAP sensor reading is
    unstable NEVER put a restrictor in the MAP sensor line because you will put the
    injection pulses (and possibly ignition advance) out of time with the pressure
    waves and you will end up trashing the pistons and/or bearings. Find a better
    position in the plenum for the map sensor line or if you have multi throttles
    connect EQUAL length hoses to a small chamber and take the MAP sensor line from
    there.

    The SM4 has some expanded parameters in the boost control compared to
    SMC/SM2/SMD ecus. You can map the CRO against different boost targets as well as
    rpm which means you can get exactly the right values even if you have a target
    just above wastegate pressure and another one way above. You can also alter the
    Dynamic Comp against rpm so you can have fast response at lower gas flows while
    not losing control of the boost at high rpms with big turbos and wastegates.
    1977 RA28 Celica - 1MZ-FE Members Rides
    1996 FZJ80 Landcruiser.
    Email : [email protected]

  11. #11
    Toymods Vice President Chief Engine Builder TheToyman75's Avatar
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    Default Re: Autronic SMC boost control help

    Joel,

    What was the end result of all that info lol, Ie is it nice and stable now or are you still fine tuning it ?
    1971 2T-B Celica TA22 ST.
    1973 2T-G Celica TA22, aka "The Unicorn".
    1975 2T-G Celica TA27 GT
    1976 2T-G Celica TA23, aka "The Colonel".
    1985 3F Auto FJ62 Landcruiser
    1989 7M-GTE MA70 Supra, aka "The Poopra"

    History: Rods Classic Celica Sampler thread.

  12. #12
    back into it Chief Engine Builder
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    Default Re: Autronic SMC boost control help

    Quote Originally Posted by TheToyman75
    Joel,

    What was the end result of all that info lol, Ie is it nice and stable now or are you still fine tuning it ?
    Welcome back rod, how was the trip?

  13. #13
    Forum Sponsor Carport Converter TurboRA28's Avatar
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    Default Re: Autronic SMC boost control help

    Hey Rod, hows it going? Mate i haven't had a chance yet to put all that info above into practice. Just putting up with how it is for now.

    I also need to talk to you about another boost valve when you are back at work
    1977 RA28 Celica - 1MZ-FE Members Rides
    1996 FZJ80 Landcruiser.
    Email : [email protected]

  14. #14
    Toymods Vice President Chief Engine Builder TheToyman75's Avatar
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    Default Re: Autronic SMC boost control help

    Back at work Monday dude

    And thanks Mick, Trip was great, car went well and we drove at night so Kids were alseep.
    1971 2T-B Celica TA22 ST.
    1973 2T-G Celica TA22, aka "The Unicorn".
    1975 2T-G Celica TA27 GT
    1976 2T-G Celica TA23, aka "The Colonel".
    1985 3F Auto FJ62 Landcruiser
    1989 7M-GTE MA70 Supra, aka "The Poopra"

    History: Rods Classic Celica Sampler thread.

  15. #15
    back into it Chief Engine Builder
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    Default Re: Autronic SMC boost control help

    Quote Originally Posted by TheToyman75
    Back at work Monday dude

    And thanks Mick, Trip was great, car went well and we drove at night so Kids were alseep.
    Yep, i know the feeling, makes for plesant driving and the kids stay happy

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