Boosting Too Quickly And Engine Cutting (R32 Gtst)

[nj1]

Hi All,

So I have recently got my car tuned for ethanol and have been having some problems

Car: 1992 R32 Gtst

Turbo: Hypergear ATRSS1

ECU: Link G4

Power 380 rwhp @ 22 psi , 700 Nm

The car seems to hit close to 28 Psi by 5000 rpm and then the engine cuts ( programmed to cut if the boost is too high)

Initially one of the lines that goes to the actuator popped off. the car was checked over by the tuner and put on the dyno and given a clean bill of health.

If I use 70% throttle I can rev it 7100 rpm and all is fine, however 100% throttle in 3rd results in misfire/spitting noise at 6000 rpm which I can push through by reducing throttle, but once in fourth it hits 28psi and the engine cuts. Also when it cuts the cat over temp light flashes up.

All hoses are secured and zip tied, solenoids were check, wastegate checked etc. by the tuner the first time. Prior to ethanol, it was putting out 315 rwhp on 98RON with no problems

Is it a problem with the turbo or ECU tuning problem? Any help is appreciated!

[NISR32.5]

Check all your lines for splits, I had this problem on my Gtr and it ended up being a tiny split in a vacuum line causing it to over boost.

[MBS206]

You have a boost control issue. Find out why.

[hypergear]

get rid of the cat first? Its good power for a RB20det, I'm sure you get more power without the cat.

Check to boost controller and the hoses that goes from it to the actuator and vacuum source. Usually it won't boost creep if its not doing that on the dyno.

[nj1]

get rid of the cat first? Its good power for a RB20det, I'm sure you get more power without the cat.

Check to boost controller and the hoses that goes from it to the actuator and vacuum source. Usually it won't boost creep if its not doing that on the dyno.

It's got a high flow cat on it, need the car legal.

The hoses going to the actuator are all fine, all tight and no splits. Other causes/reasons causing the wastegate not to open?

As mentioned the turbo was running great before the E85 conversion. I am at a loss why it has been on the dyno twice and performed fine but as soon as it hits the road different story

[On Edge]

Really interested to hear the solution

[Ben C34]

Get car tuned properly?

[hypergear]

As mentioned the turbo was running great before the E85 conversion. I am at a loss why it has been on the dyno twice and performed fine but as soon as it hits the road different story

Usually it is the opposite as the engine has more ramp load with wheels locked up on the rollers. You can by pass the boost controller and run vacuum source directly into the actuator and see if that helps in any way.

[nj1]

Usually it is the opposite as the engine has more ramp load with wheels locked up on the rollers. You can by pass the boost controller and run vacuum source directly into the actuator and see if that helps in any way.

Double checked there was no vacuum leak by running a new line, same problem

Then I bypassed the boost controlled, vacuum line straight to the actuator and seems a lot better, doesn't over boost. I am guessing the solenoid is malfunctioning not allowing the waste gate to open?

If I bypass the boost controller/solenoid I need to get the car tuned again I am guessing. To run higher boost it will have to go through the controller right

[GTSBoy]

You won't have to retune it to run less boost. Less boost is already covered in a "more boost" tune by definition. You do realise that you can run any boost you like by not pushing the throttle pedal down as much, right?

And yes, to run higher boost you will need to run the boost controller. You can test the solenoid easily enough. Give it 12V + earth and see if it changes state. If it does then the solenoid is fine. If it doesn't then it's munted. If the solenoid checks out, then you have to suspect either the wiring or the controller box itself.

[nj1]

You won't have to retune it to run less boost. Less boost is already covered in a "more boost" tune by definition. You do realise that you can run any boost you like by not pushing the throttle pedal down as much, right?

And yes, to run higher boost you will need to run the boost controller. You can test the solenoid easily enough. Give it 12V + earth and see if it changes state. If it does then the solenoid is fine. If it doesn't then it's munted. If the solenoid checks out, then you have to suspect either the wiring or the controller box itself.

On the track I want to be able to go 100% throttle in 3rd and 4th on a straight and shift close to 6700 rpm/7000 rpm as I can without having to worry about overboosting/boost

So if the car has been tuned with a boost controller and now I have by-passed it completely that will obviously affect the power/torque curve that I had with it yes?

Either way it will go back to the tuner to get sorted

Edited June 9, 2014 by nj1

[GTSBoy]

On the track I want to be able to go 100% throttle in 3rd and 4th on a straight and shift close to 6700 rpm/7000 rpm as I can without having to worry about overboosting/boost

So if the car has been tuned with a boost controller and now I have by-passed it completely that will obviously affect the power/torque curve that I had with it yes?

Either way it will go back to the tuner to get sorted

I don't think you understood what I wrote at all.

The point about throttle control being a way to run less boost was to make the point that a car set up to run 20 psi can be run at 10 psi by not opening the throttle - and it doesn't need to be retuned to do so because.........surprise surprise, if the tuner knows what he is doing has has tuned the whole map, which includes less load at all rpm points. It is self obvious that this is the case.

So, if you have indeed removed your boost control and are now forced to run less boost, you WON'T need to get it retuned. You would in fact be far better off trying to work out why the boost control wasn't working and get it going again.

[32rrr]

If the turbo is internally gated, check that you havent wound to much preload onto the actuator causing it not being able to open far enough to bleed boost off.

[1400r]

wonder if the cat over temp light is used as knock light by the link?

just run it without the boost controller till you either get a new boost control and a dyno check to make sure prev tune is still ok

or buy a turbo tech bleed valve and then get the tune checked on high boost via the bleed valve

really it just sounds like running 28psi and not the 22psi its tuned for it causing the problem

whatever you do if it holds 22psi it should be ok

[nj1]

So the car went on the dyno this morning and the issue was identified as the engine misfiring, new coilpacks ordered.

How does the misfiring relate to the over boosting issue?

[GTSBoy]

Fuel burning in the exhaust manifold (instead of releasing its energy in the cylinder and delivering the power to the crankshaft) delivers massive energy to the turbine and you lose control of boost.

[nj1]

Fuel burning in the exhaust manifold (instead of releasing its energy in the cylinder and delivering the power to the crankshaft) delivers massive energy to the turbine and you lose control of boost.

Thanks, makes sense

[1400r]

would have thought if you'd paid for a dyno run they could have told you why

[nj1]

Problem solved, put in denso pencil coils and the car is perfect again, was able to modify the tune to get some better mid range response