GT28RS = No POWER , Help please

[Andy Cotton1]

I have a 1.8T in an Elise running GT28RS and up until a few days ago it was producing a healthy 320BHP.

I driving home from having new tyres fitted and cruising at 60mph - the boost gauge showed vacuum as usual.

I then heard a funny noise a bit like a electrical space invader type noise (like sometimes if you have your radio on and lights and rev the engine sometimes you can hear an electrical type noise through the stereo).

Anyway, this happened about 5 times on the way home. I have now found if when this noise occurs I put my foot down to accelerate the noise gets louder and I have no power. The boost gauge reads ZERO the dump valve does not expel charge air when I change gear but you can here the turbo revving up but not up to full speed.

I have checked for boost leaks everywhere. I have changed the N75 and associated pipe work. I have taken the inlet manifold and checked for leaks and the breather. I have disconnected the pipe going to the wastegate and put the compressor onto it and saw the wastegate being activated.

It's a very strange noise, I have taken the intake pipe off the turbo and all vanes are present but it is making a very strange noise when you turn off the engine (like dry bearings) I've checked the oil feed and all is good.

I have not checked the exhaust side. When I revved the engine It sounds like the noise (space invaders noise) is coming from the turbo but I could be wrong. As I rev the engine and listen with a screwdriver pressed against my ear I would say the turbo was vibrating too much as you rev it ?

I'm pretty sure it's not a boost leak, but why would I have no charge ? The pipes are all SAMCO and the dump valve is a piston type Turbosmart.

Any ideas ?

 

[Andy Cotton1]

Forgot to mention, sometimes it will make power (ie boost gauge goes to 1.2 BAR) when I put my food down when the noise is not present, but when the noise is present it makes NO power or boost (ie Zero bar on the gauge)

Why does it one minute make power and then the next make no power. It does seem to be getting worse though i.e noise there all the time and no power and it gets louder as you try to demand power.

 

[ibizacupra]

bearings failing... my guess

 

[Andy Cotton1]

I'm not sure how bearings failing (Turbo was only rebuilt 6 months ago) would cause my symptoms without other signs - like excessive smoking etc...have you come across this before ?

I have inspeected both the turbine and impeller wheels and they are all intact.

Could it be that the wastegate is open all the time ? I put compressed air on it and it appears to be operating correctly.

 

[ryan_s3]

i was going to say is it smoking?
disconnect all boost control and run straight off actuator pressure if still no boost it's the turbo.
could always move the boost gauge reading to behind the turbo outlet to eliminate leaks.

 

[Andy Cotton1]

The Boost control on my car is very simple, I have tried a 2nd N75 and the same results. If i electrically disconnect the N75 is should expect about 0.7Bar (I have tried this in the past and got this figure) it's funny why the boost gauge only goes to 0 Bar, if it went to 0.7 I would suspect the boost control. I know the 2nd N75 is serviceable.

Could the wastegate be opening too early ? I don't think the turbo isn't spinning up to full speed either. It appears not to be making Boost because the dump valve isn't venting either.

I've tried a 2nd dump valve as well with the same results.

Can I somehow disconnect the waste gate and go for a gentle drive ? Can I mechanically disconnect it or take the pipe off and blank it ?

I need to eliminate that it's not the waste gate actuator but not sure how to do it ?

Advise anyone ?

 

[ryan_s3]

you can test the actuator by applying pressure to it then seeing if it moves the rod.You could do up the actuator to massive preload or disconnect the pipe from the compressor side of the turbo to the actuator.
Be very Careful!

 

[ryan_s3]

just thought,probably already checked but any play in shaft any marks on the housing,spins freely?

 

[Andy Cotton1]

I've checked the actuator movement the other day by putting about 0.7 Bar into it from my compressor and it appeared to be ok - it moved full travel, no funny noises etc..

I've inspected both sides of the turbo impellers and all looked good, no missing vanes no debris.
The turbo spins freely no excessive play, when you turn the engine off at tickover the turbo continues to spin for about 10 secs before it stops.

I'm lost !

If I disconnect the pipe going to the actuator do i need to block the end up ? or leave it open ? I don't want to damage the N75.

 

[Andy Cotton1]

I've just done a quick test.

I totally removed the actuator.

I wire locked the waste gate shut.

Removed the intake hose from the turbo (air filter side of the turbo) and started the car up and revved up to 3K ish.

The turbo is still making this weired noise but as I was revving I was getting charge air blowing back towards the airfilter ie the wrong way on the overrun. As I revved my hand was being sucked into the turbo as expected but on the overrun charge air was being blown back the wrong way.

I'm not too sure if this is normal or not, looks like the turbo has to come off for another strip down.

 

[ryan_s3]

With the turbo wire locked and the boost guage reading from the turbo outlet(intercooler pipe) are you getting any positive boost? Turbo does sound goosed mate.

 

[Andy Cotton1]

No, I wouldn't really expect to see +ve boost pressure with the engine not under load i.e reading off the gauge.

When I revved the car my hand was being sucked towards the intake as expected but when the throttle was released I didn't expect to feel air being forced the wrong way i.e towards the air filter.

This could be normal, I've just never done this kind of test before.

 

[ibizacupra]

have you driven it "carefuly" with the wastegate wire locked shut?
do you get boost climb?

 

[Andy Cotton1]

No Bill I haven't, I just revved it in the garage, it was the fact I could hear this unusual whine noise I guess it's made no difference.

 

[ryan_s3]

You should be able to drive carefully just to see +ve boost.

 

[Andy Cotton1]

Yes I think i need to take it for a drive, tomorrow.

 

[ibizacupra]

No Bill I haven't, I just revved it in the garage, it was the fact I could hear this unusual whine noise I guess it's made no difference.

the whine noise would likely be rotating parts which is turbo

 

[Andy Cotton1]

Took the car for a drive with the actuator off the car and the wastegate wired shut.

Made no difference what so ever, I would say it is now worse with a constant whine with no boost or power.

Looks like the turbo needs to come off and sent for a strip down.

 

[ryan_s3]

yes definetly andy,why not get it upgraded at the same time?

 

[Andy Cotton1]

Would do but the car's already an animal ! don't forget it only weighs 800kg with 320BHP on tap.

The problem with an upgraded turbo would be I would need to upgrade the valves in the head and possibly the Pistons then the clutch............£££££££££££ where does it stop ?

I've got to be a bit careful in terms of heat management cos the cars made of plastic !! In theory a bigger turbo would create more heat.

Plus the biggest hurdle would be the missus !