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Discussion Starter · #1 ·
I have noticed a lot of you are using the Unichip piggy back ECU and a additional Electronic Boost Controller. Is that just so you can adjust boost on the fly? I thought the Unichip controlled the boost solenoid directly.

I have an FD3S and considering getting a WRX in addition to my Mazda and am trying to learn the slight differences in tuning the two. In the RX-7 world our piggy back ECU and things like the PowerFC stand alones don't usually control boost (notice i mention usually, I know some do) so I use an HKS EVC on my FD.

Just wondering, any info would be greatly appreciated.
 

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The Unichip relies on the stock selenoid to control boost which isn't very good. I never use the Unichip for boost control on an aftermarket turbo. On a stock one it works okay but still recommend an seperate EBC if at all possible. This also gives you the flexibility to adjust boost on the fly.
 

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Discussion Starter · #3 ·
Dan,
Thanks for the info. Which EBC set up works best with the stock turbo? Is the fuzzy logic on the Greddy Profec able to "learn" the stock turbo? As you probably know on my FD and other twin turbo set ups the fuzzy logic of such controllers goes haywire.

Also is it me or do most of the downpipes seem to have a blocking plate for the wastegate outlet port?

-Brian
 

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R-32 Dreams said:
Dan,
Thanks for the info. Which EBC set up works best with the stock turbo? Is the fuzzy logic on the Greddy Profec able to "learn" the stock turbo? As you probably know on my FD and other twin turbo set ups the fuzzy logic of such controllers goes haywire.

Also is it me or do most of the downpipes seem to have a blocking plate for the wastegate outlet port?

-Brian
most people say to steer away with the fuzzy logic because, as you put it, it "goes haywire!" I'm using a unichip and Greddy Profect B without any problems. The EBC makes response a lot better plus you get easier boost adjustments.

hth, -C
 

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So would you recommend using an EBC instead of the ABC that's bundled with the TurboXS chip?
 

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So I take it that the SBC-id or similar EBC comes with a new selenoid? I have read that there are different types 2 port/ 3 port, I may be wrong on that, but if not what does the SBC-id come with. Also once you install the EBC would the Unichip be only controlling fuel and timing.

Thanks

Troy
 

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One of the (few) things I like about the Unichip boost control, is that it uses throttle position to control boost. That way, I have wastegate boost up to about 60% throttle, and full boost above 60%. The stock TXS piggyback board is set up for 40%, but a simple resistor change will make it a more driveable 60%.

To me, this makes more sense than always-full-boost (MBCs) or EBC boost based on RPMs/gear/speed/whatever. The car behaves more like a NA car, power being generally proportional to throttle position.

I'd like to get a EBC for more accurate boost control, and to be able to change it on the fly. Is there a EBC out there that can adjust boost based on throttle position?
 

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I do like the boost set to the TPS but going from say 6-7psi to full boost can be harsh at times, the 60% setting may be better the the 40% for that though. From what I have read from others with EBC is that the boost onset is smoother.

God, with your SBC-id, I assume that it needs to tap into some of the wires on the ECU, do you tap green wires on the TXS harness or the factory wires? I saw some where that some one sells a plug for the SBC-id for the WRX so this may be an option too.

Troy
 

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Rocky WRX said:
One of the (few) things I like about the Unichip boost control, is that it uses throttle position to control boost. That way, I have wastegate boost up to about 60% throttle, and full boost above 60%. The stock TXS piggyback board is set up for 40%, but a simple resistor change will make it a more driveable 60%.
Not sure why this is a problem. The more boost, the more power at full or part throttle. As for wire tapping, no the SBC-id just needs power and ground. No ECU wires need to be tapped UNLESS you get the pwoer meter or the optional harness. And yes you can tap the Turbo XS harness wires. No need to touch the actual vehicle wiring.
 

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God said:
Not sure why this is a problem. The more boost, the more power at full or part throttle.
Maybe I'm missing something, as I've never used a MBC or EBC, but the problem, as I see it, is twofold. Full boost at part throttle can result in high EGTs. This is a widely reported problem with MBCs, presumably because more boost at part throttle results in a leaner A/F ratio.

Secondly, 60% is a magic number. Below a TPS reading of 60%, the ECU runs in a closed loop control scheme, where A/F ratios and timing are controlled in realtime by the ECU, based on other inputs such as O2 sensor readings. Above 60%, it goes open loop. This is where the TXS guys do their Unichip timing and A/F tuning to handle increased boost.

The Unichip piggyback harness, as shipped by TXS, applies wastegate boost below 40% and full boost above 40%. This results in a jumpy, overly sensitive accelerator, as you transition past 40%. It can also lead to higher EGTs between 40% and 60% TPS.

This is only my experience, so let me know if I'm missing something. If there were a EBC that could ramp boost as a function of TPS, that would be the holy grail in terms of driveability and N/A-like throttle response, IMHO. God, is your EBC set for full boost all the time, or does it ramp boost as a function of some other parameter (RPMs)? Is the throttle response smooth or jumpy? Do you have any part-throttle EGT issues?
 

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I think someone has been reading too much paranoia stuff on i-club. Part throttle high boost is not a problem for the ECU. I occasionaly had high boost at part throttle when I had the stock turbo and it never caused high EGT's or problems in drivability. Now the Turbo XS Boost control I have no idea since I never use it but the SBC is perfect boost control everytime. It will try to maintain that wastegate shut as much as possible at either part or full throttle which is what you want for response and spool up time. Now with a bigger turbine you'll NEVER get more than 10 PSI at part throttle. It just doesn't happen so it becomes a non-issue but I do know there are places on the map where it could be smoother. Then again you have to see where I am at with power and remember that this is a piggy back system we're talking about. I am having my ECU remapped soon to see if we can improve drivability a little and develop mapping for my upcoming Stage II++ setup.
 

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TypeC said:


most people say to steer away with the fuzzy logic because, as you put it, it "goes haywire!" I'm using a unichip and Greddy Profect B without any problems. The EBC makes response a lot better plus you get easier boost adjustments.

hth, -C
Calvin, would you mind giving me some tips once I get the EBC? Thanks.....
John
tex-wrex2

Another Honda Head in Subie Clothing;)
 
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