Too much BOOST

[richardspeed]

my car is boosting to 18psi with no boost controller, what could be the problem, it has a straight through exhaust with a small back box, could it be the flow of the exhaust that is making it spool up more?

[let_nova]

maybe the actuator is wound in too much

[let_nova]

anyway whats wrong with 18psi?

[richardspeed]

18psi is great but its not got a upgraded ecu, which way do I need to wind the actuator, I can see from the top easy, bar into or away from actuator?

[craig green]

I'd look for a vac leak in the actuator /amal valve piping.

Assume its a C20LEt?

[richardspeed]

Yeh its a LET, were is the amal valve, the boost guage goes into vac when you let off then goes into boost when under load.

[novaguy08]

its possible that the backpressure in the exhaust or lack of is the problem as it will be moving much more freely, winding in the actuator should sort the problem, or chips would do a goodun :D

[richardspeed]

My friend had a RX7 and he had a straight through exhaust put on it and the boost increased loads, thats what I was thinking, I am getting a custom made exhaust made for it in the next week or so because its to loud for the track, which way does the bar go to wind in?

[Lee H]

It must be chipped as the ECU will cut the boost at 14 psi if not and you'll nearly go through the window.

If its been bodged and isn't chipped or running higher fuel pressure i'm surprised it hasn't melted yet.

[richardspeed]

How can I tell the ecu has been chipped?

[Jack]

its possible that the backpressure in the exhaust or lack of is the problem as it will be moving much more freely, winding in the actuator should sort the problem, or chips would do a goodun :D
...Boost creep. Reducing backpressure in exhaust means the wastegate can't flow enough gas round the turbine so more gas flows over it and increases boost uncontrollably. Usually, as Lee says, a fuel cut will stop things; if thats not happening I'd be worried

[Mike]

; if thats not happening I'd be worried

Oh yes!! No cut could mean, as Lee said ECU has been tampered with (to override fuel cut for more power) OR somewhere along the line somethings not working as it should be! Thus possible kaput engine when giving it beans.

[novaguy08]

ahhh boost controller time me thinks

[richardspeed]

Any advise on were I can put the T for the boost controller, which pipe and were?

[Lee H]

How can I tell the ecu has been chipped?

Open it up and see what two chips are in it. Thats the only way I know of. If it is chipped you then need to check fuel pressure to see if it has been increased for the extra boost.

LET's normally have a boost spike where they boost higher initially when you put your foot down but then backs off slightly after a couple of seconds and holds this boost. If its not doing that its likely the amal valve has been disconnected and a bleed valve fitted.

[Lee H]

Any advise on were I can put the T for the boost controller, which pipe and were?

No offence but if you don't even know the basics of how the turbo works and controls boost you shouldn't really be fitting a manual boost controller on your own, you will more than likely end up damaging your engine.

[richardspeed]

I've had a look and I can't see a bleed valve.

[richardspeed]

When I fitted my avcr on my Skyline it was the pipe from the plenum to the actuators, just wanted to make sure it was the same.

[Lee H]

There should be a vacuum from the actuator going to the amal valve and a vacuum from the turbo housing going to the amal valve. The amal valve then connects to the large breather going from the rocker cover to the turbo inlet. Do you have this set up?

[Lee H]

When I fitted my avcr on my Skyline it was the pipe from the plenum to the actuators, just wanted to make sure it was the same.

Correct. However you will need to leave the amal valve plugged in so the ECU light doesn't come on.

I wouldn't bother with a boost controller as if the ECU is standard there will be no benefit. If the ECU is chipped the amal valve can still control the boost.

[richardspeed]

Yes I do have this set up.

[Lee H]

Yes I do have this set up.

Pretty sure ECU must be chipped then otherwise it would be cutting boost at 14psi.

[richardspeed]

Were do they normally put the ecu's in these cars is it under the steering wheel?

[Lee H]

On the shelf above the pedals. Should be able to see from the tabs around it if its ever been opened.

[richardspeed]

I have the ecu off, I have taken the metal cover of but I can't see much because its like a sandwhich, two green boards but I can't get them open.

[Lee H]

You need to push the plastic pin in the middle of the boards out first and then if you look where it plugs in you will see two tags you need to push in with screwdrivers and then you can pull the top board and pins out and see in between them. hard to explain.

[richardspeed]

Can't find the two clips?

[Lee H]

They are where the plug goes in, one each side at the top.

[richardspeed]

I have messed about with them but nothing is happening