Overboosting Issue

[bad_rb20]

hey all, just acquired my car off a fellow forum member:) anyways after owning it for a couple of weeks am stoked with it couldn't be happier.

Anyways after taking it for a couple of spirited drives, i'm finding the car is overboosting in 3rd gear +.

Car has the following

RB25 motor

Power FC

AVC-R

250-270rwkw

The car has 2 settings 1bar and .5 bar

When i set it at 1 bar it goes to 1.1 bar in second holds then once i go to third boost keeps rising seen it go to 1.4 bar each time but don't know if it will keep going, as i dont wanna be cleaning bits of turbo out of my cat(if it has one) still to check this.

When i have it on .5 bar 2nd gear goes to .7 bar then holds, once go in to third it seems to go up to 1.4 bar again.

Clutch is on its way out so in third it generally just slips and boost goes up

BOV is blocked off which is the next thing to change(unsure if this could be doing this)

I'm unsure to why it is doing this, and really want to fix the problem,

Any help or experiences would be appreciated.

Thanks all in advance

Nath

[bad_rb20]

anyone got any ideas?

[MercuryMotorsport]

The obvious area to investigate is the AVCR. I would suggest taking it to your local dyno and trying to run the car just on wastegate to see what it is doing, then tune the avcr on its low and high setting. Also, is it just recording a peak of 1.4bar or is it holding that throughout the rev range?

Boost can be different in the higher gears, as it allows the engine to load up, which in turn works the turbo harder creating more boost on the same boost controller solenoid rate.

[bad_rb20]

thanks mate, i will look into getting a retune as its probably due.

[paulr33]

agree retune the AVCR

there is a detailed video on youtube on how to tune the AVCR correctly

the old HKS controllers did a self learn mode when you take off in 3rd gear and run to redline 3 times

it would then during this process watch the wastegate pressure and manifold pressure and how long it took to boost build

so i suggest when setting up your AVCR you base it off 3rd gear runs

ie dont tune boost in 1st or 2nd, too much ramp, too much roadspeed for accurate control

[bad_rb20]

thanks paul, i will look in to retuning the AVC-r. in relation to it hitting peak at 1.4bar. not sure if it will keep going but when i record on the defi controller and hit the recent button it states 1.4bar peak. dont know if this helps.

[Dose Pipe Sutututu]

Turn down the gains on the AVC-R, the previous owner must have the gain set too high.. The AVC-R also allows you to graph the boost vs time. You will see that it might spike to 1.4bar but then drops to 1.1/1.0

Keep on lowering the gain till you get good results, I tend to have my gain set so it spikes 0.1bar past my desired boost as it brings on boost a tad quicker.

Don't use these settings as gospel, each turbo/actuator is different.

Set using PowerFC Boost kit:

0.8 bar 40 gain / spikes to 1.0 bar

1.0 bar 48 gain / spikes to 1.1 bar in 3rd

1.15 bar 54 gain / spikes to 1.2 bar in 3rd

1.30 bar 62 gain / spikes to 1.38 bar in 3rd

[bad_rb20]

i've had alook at tutorials but they are all for the newer avc-r. mine is an old school item no adjustable features.

Power FC doesnt seem to be set up for boost as when monitoring shows ---- nothing.

I'm starting to think it's a wastegate/actuator problem as it is internally gated.

What does evri1 else think?

Turn down the gains on the AVC-R, the previous owner must have the gain set too high.. The AVC-R also allows you to graph the boost vs time. You will see that it might spike to 1.4bar but then drops to 1.1/1.0

Keep on lowering the gain till you get good results, I tend to have my gain set so it spikes 0.1bar past my desired boost as it brings on boost a tad quicker.

Don't use these settings as gospel, each turbo/actuator is different.

Set using PowerFC Boost kit:

0.8 bar 40 gain / spikes to 1.0 bar

1.0 bar 48 gain / spikes to 1.1 bar in 3rd

1.15 bar 54 gain / spikes to 1.2 bar in 3rd

1.30 bar 62 gain / spikes to 1.38 bar in 3rd