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Tuning over 1.55bar


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BenTTU

BenTTU

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med9/med17.1.1 RSTT, RS3 8P & RS3 8V PFL

BOOST CONTROL

We have received many questions about stage 2 and 3 cars and have been asked about boost control.

Some insight about the ecu's in question.
From factory they put a cap on the boost to be able to only tune to 1.55bar, many tuners have tried to go above the 1.55bar and failed. When you do try to go above the 1.55bar the throttle body slams shut or the MAP sensor malfunctions leaving the car in a poor state of tune.
Tuners have been getting around the boost limit by open loop circuit on the n75 boost controller solenoid in the ECU, this is a disaster waiting to happen.
First of all the throttle body does not open 100% and only goes to around 96%, straight away the tune has started off with a problem. Bypassing the N75 means all fail safe features have gone apart from the throttle body slamming shut. Having no boost control means you could well be driving around with a vac leak or boost leak and be none the wiser. If the ECU cannot cut boost to highlight an issue, unfortunately this means turbo failure or even worse engine failure with no warning. Also if you add aftermarket products like WMI you need to plumb in the fail safe to the N75, if the N75 is not coded correctly and your wmi fails and sends a fail safe signal to the N75 it will cut your boost, this in turn will save your engine, But it will not cut your boost if the n75 has been bypassed in the ECU.
Then we have the fact of how the boost builds down low, due to having open loop the n75 duty is fixed once you go wide open throttle at low rpm the turbo will over speed down low, spiking the boost at a very aggressive rate. This will cause torque to spike resulting in massive stress on the pistons. Ie ring landing failure.


Also driveability is not as good when tuners have bypassed the N75 and this is also a tell tail sign, light throttle driving your car will randomly build boost and give you a surging type of feel, Also if you go to half throttle you get the sensation the car is getting away from you as you can feel the boost over building.

Over the last 2 years we have been hard at it developing a solution for the TTRS 8J, RS3 8P & 8V PFL. We now can map to 2bar of boost with full boost control. we control the boost via the N75 duty cycle as you should from factory. Also the throttle body sits at 100% open on full throttle. Key to having the N75,if we get under boost, it goes into limp mode, over boost goes into limp mode.Any other major issues IE running lean, the first port of call is to shut the throttle body then cut boost to put you in limp mode to prevent engine failure. If you do not have perfect boost control this will not happen.

We are very excited to keep moving forward and can say we are the only tuners in the UK to develope such boost control for stage 2 + cars that need to go over 1.55bar.

Ben

Edited by BenTTU, 28 November 2021 - 09:52 AM.




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