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Liberty with Link Thunder

Road Tuning

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Discussion and questions related to the course Road Tuning

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I've been tuning my 2007 Subaru Liberty GT-B with a built motor, and Link Thunder ECU on E85. During road tuning the car in 3rd gear it comes on boost hard but then feels like the car runs out of power and the revs don't pull quickly towards the redline. Currently running 14psi which is wastegate pressure. Looking at the logs the car is still making 14psi during the whole run. It doesn't appear to be hitting a boost cut or any other limit. I've installed fresh spark plugs (SILFR6A) gapped at 0.6mm. The old plugs had a light brown colour which I believe is normal. The car isn't suffering from detonation.

The car was previously tuned on the OEM ECU running 20psi on 98 oct. and this problem didn't occur. Trying to diagnose if there is a mechanical problem or something is wrong with my ecu setup. I can provide more details if need be.

Thanks for your time.

Post a log and tune file so we can take a look.


You'll see a pull in second then third gear. Car began to misfire at 6500rpm, limiter is set to 7500rpm. Looking at the log the mixtures seem a bit rich under WOT, what do you think?

Thanks for your help

Attached Files

A few thoughts:

VVT is not working at all. Table has zeros in it and the avcs solenoids arent set up right either. Probably shouldnt affect the top end much though.

It is very rich, 0.69/0.70 Lambda, it will be pretty hard to light up at that.

Injectors are topped out. 90% DC at 6000, 102% DC at 6500RPM.

Your knock target table has zeros in it so the ECU is applying maximum knock retard (4deg) up until the RPM lockout. I suggest you set the retard limit to 0 until it is tuned.

Im no subaru guy but your ign timing looks pretty low considering only 12psi boost (13-14deg at redline), I would have thought once you were beyond peak cyl pressure you would be able to put more in towards redline.


Thanks for your help. It turns out the rich mixtures were the culprit, I was a bit paranoid about running it too lean. I made a small adjustment and the car certainly feels a lot better. What I'm curious about is how is the injector DC calculated? How is it possible to get a duty of over 100%? I'm using the Traditional fuel equation, in this case I haven't put the size of the injectors in so how does the ecu know they are maxed out?

Thanks again, Kiel

You are correct it is impossible to have more that 100% DC. We allow the ECU to calculate/display more than 100% just so you know how far away you are.

The ECU does not need to know injector size to calculate DC, DC is just the ratio of on time vs off time.

How do we end up with a number larger than 100%? If the fuel calculation is arriving at a 11ms pulsewidth but there is only 10ms of cycle time, then the requested DC is 110%. Of course the ECU cant open the injector for longer than 100%, but it is still calculated so you no how bad things are.

You raised another interesting point about my VVT solenoids not being setup correctly, could you expand on this? I have Aux 1 as LH Inlet and Aux 2 as RH Inlet. DI 2 is the signal for RH Inlet and the LH Inlet signal is under Trigger 2. This all seems correct to me?

Under VVT settings I have chosen the Subaru AVCS EJ25 as my motor only has AVCS on the inlet cams.

Set the frequency on aux 1 & 2 to 300Hz. Also, your LH camshaft error counter is counting up and your RH cam is showing 2-3deg advance in its home position so that suggests the offsets arent set correct.

Use the cam angle test function to determine the correct offsets. Read the help file topic: > G4+ ECU Tuning Functions > VVT Control > Tuning VVT Control > Cam Angle Test

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