[Mk2] [Turbo] Rev3 Turbo not boosting

[rob6539]

Hi guys, was wondering if I could get some advice please?

Putting the finishing touches to an rev3 turbo swap into a UK N/A rev3 body; This is the first time I've driven the car since the conversion and have had a few issues, the most important one is that there is no boost.

I've got an aftermarket boost gauge fitted and the needle only moves between negative and zero. Also the check engine light is on.

I didn't give the engine a hard time at all before this happened.

Any ideas where to start looking?

Could this be an electrical issue rather than a mechanical one? As I've retained the dash wiring loom from the NA and paired it to the Turbo loom from the passenger foot well back to the ECU.

Thank you

[bobhatton]

Hi guys, was wondering if I could get some advice please?

Putting the finishing touches to an rev3 turbo swap into a UK N/A rev3 body; This is the first time I've driven the car since the conversion and have had a few issues, the most important one is that there is no boost.

I've got an aftermarket boost gauge fitted and the needle only moves between negative and zero. Also the check engine light is on.

I didn't give the engine a hard time at all before this happened.

Any ideas where to start looking?

Could this be an electrical issue rather than a mechanical one? As I've retained the dash wiring loom from the NA and paired it to the Turbo loom from the passenger foot well back to the ECU.

Thank you

First check the ECU codes, that should tell you what is wrong.
Where is the boost gauge plumbed into?

[rob6539]

Ok I’ll try and get a guide for obtaining the ECU codes, thanks.

The aftermarket boost gauge is plumbed into the bottom right hand side of the inlet manifold (cambelt side); using a t piece between a short hose that looks like it connects the inlet manifold to something on the fuel rail.

I haven’t retained the standard boost gauge as I’m using the clocks from the NA.

[bobhatton]

http://manual.teq.org/

[rob6539]

Thank you for the link.

With regards to the error codes, I've picked up a '42' (Vehicle Speed Sensor Signal); which makes sense, as the speedo isn't currently working.

I'm guessing this is a wiring issue between the turbo engine loom and the remaining wiring on the NA shell. But would it cause no boost?

I'm going to take the down pipe off to see if maybe the actuator is stuck open.

Unless you've got any other ideas? I'd be grateful for any advice.

Thanks again

[rob6539]

http://manual.teq.org/

Thank you for the link.

With regards to the error codes, I've picked up a '42' (Vehicle Speed Sensor Signal); which makes sense, as the speedo isn't currently working.

I'm guessing this is a wiring issue between the turbo engine loom and the remaining wiring on the NA shell. But would it cause no boost?

I'm going to take the down pipe off to see if maybe the actuator is stuck open.

Unless you've got any other ideas? I'd be grateful for any advice.

Thanks again

[rob6539]

I've taken the down pipe off the car and had a look in the exhaust housing of the turbo.

Waste gate was closed and I could open it with a screwdriver blade and it snapped closed nicely.

So that hasn't really answered why the engine is not boosting.

Could it be a VSV issue?

[Slarty]

If you're not boosting above 0 (atmospheric pressure) it can only really be one of two things, the turbo isn't producing boost (either a broken shaft between the intake and exhaust turbine or the wastegate being jammed open (which you've ruled out)) or that you have a total boost leak, I.E. a hose completely off between the outlet of the compressor and the throttle body.

[bobhatton]

You have got full throttle, no slack in the cable?
And are trying the car with foot to the floor in say 3rd gear?

[rob6539]

No I haven't driven it hard at all. Just basically limped it around. Especialy after the check engine light popped up, I didn't want to thrash it.

I'll have a look at the throttle cable and I'll try and put my foot down and see if I get any boost.


Thanks

[rob6539]

You have got full throttle, no slack in the cable?
And are trying the car with foot to the floor in say 3rd gear?

Throttle cable looks good and is responsive; took the cat out for a quick run today gave it a bit more of a spirited drive through the gears.

Still no boost

I've also blanked off the pipe on the turbo actuator, that feeds the vsv. This didn't help either.

The gauge swings very nicely from negative to zero pressure, but no further. It's as if the turbo isn't there at all!

Any thoughts for possible avenues worth checking?

[shinny]

Exactly how gently are you driving the car? You won't really see huge amounts of boost if you're tickling it around below 3000rpm. Code 42 isn't going to cause a massive issue to our engine, so build some revs on WOT and see what happens.

As I said via PM (and has been suggested here) the most likely causes are a big leak on an intercooler pipe or a fault in how the boost gauge is wired up.

[rob6539]

Thanks for the PM, it is very much appreciated.

I gave the car a pretty spirited drive earlier today with my foot flat to the floor in gears 2nd to 4th. Also got it revving pretty well to see if the car was hitting an early rev limit. It revved well, but didn't go anywhere really.

The boost gauge I've got fitted is a mechanical type and fed from a hose off the inlet manifold. I'm confident that it's working well. I haven't got the standard boost gauge in the dash unit anymore though; it wouldn't be something silly like that would it?

I've sprayed the air intake pipes with leak detector and couldn't find any leaks in the joins. I know it's not ideal, as on tick-over I won't be producing any positive pressure, but would show any significant air passing over it.

What you recommend would be the best way of checking for leaks?

[Slarty]

I, personally, still think that either the turbine shaft has snapped, or the exhaust wheel has fallen off.

Quick way to check is to whip the intake pipe off and start the engine for a couple of seconds. If the intake turbine spins you can rule it out, if not, you'll need to drop the cat/elbow off to find out if it's a snapped shaft of the exhaust turbine gone west.

[shinny]

Well, if you find yourself in need of a turbo, I've got a spare CT20b... I'll probably advertise it properly next week

(Edit: Turbo is now sold)

[rob6539]

I’ve already had the exhaust down pipe off the turbo and was very relieved to find the exhaust turbine intact and spinning with the compressor turbine.

(Relieved is probably an understatement).

I’m going to take all the air ducting, from the air filter to the throttle body, off to check the pipes; then I can make sure that all the pipes are fitted tight and snug when I put them back on. Failing that I guess I’ll take the intercooler off and check for leaks.

Thanks for all your advice guys, it is very much appreciated.


Shinny – Nice plug! If it comes to it, what kind of price are you looking for the turbo?

[shinny]

Just a thought... blow off valve! Do you have one fitted? Is it possible it's stuck open?

[Slarty]

Just a thought... blow off valve! Do you have one fitted? Is it possible it's stuck open?

That's a pretty good shout to be fair. Can you hear a loud rushing type noise on wide open throttle? For you to be losing all boost, I'd have expected to have some audible clue.

Glad that your turbo is ok though

[rob6539]

I can hear a noise like a vacumm cleaner, but I assumed it was the air filter induction noise.

I've got a HKS blow off valve. I sprayed it with leak detector when I was inspecting all the joins on the inlet pipes and it spat some of the fluid out when I was moving the throttle cable.

Not a definitive test really; I'll whip it off and blow it with an air line and see if any air passes though.

[ashley]

Where are you based? Happy to have a look if you like- I'm near Newent