DIY boost leak fix

[Stuwey]

After the very bumpy TARGA stage last night and fixing a loose sway bar link, it would appear that my car had a boost leak for about 20kms, until it now has lost all boost and will not make any positive numbers at all.

Forge/SEAT front-mount jobbie, so a lot of plumbing involved.

As a do-it-yourselfer, where do you start? Any tricks, other than one-by-one?


Cheers

[Lito]

Diy VWVortex.com - DIY: Boost Leak Tester

Or you can buy one already made

1.8T K03 K04 by turboboostleaktesters.com

[h100vw]

It's not that big a job, but the bumper probably needs to come off to do it correctly. Personally, I think start at the turbo outlet pipe and work your way to the throttlebody.

If that doesn't deliver, the PCV and vac system is next.

I am assuming that you know it's losing a lot of boost 5PSI or more.

Gavin

[Stuwey]

Losing 5?

It won't make more than 5!

Cheers fellas

[noone]

Sure its a leak?
If you're getting nothing I'd think the loose connection will be very obvious, a flashlight and some time poking around under and down behind the headlights / up through the foglight grills should give you a glimpse.

[h100vw]

Check the actuator rod is still connected to the wastegate flap. Just read your first line again, no boost at all.

If you had a massive boost leak, I am sure it would stutter like mad, my S3 did when the elbow off the turbo split. As soon as you got to atmospheric pressure it fell over.

Gavin

[Stuwey]

Well it still drives 'okaaaaaay' albeit with no grunt.

It picks up off the lights, gets to 1400 or whatever revs, builds 2-3psi, then pulls all boost back to vacuum again.

Very odd. I was under it yesterday but didn't notice anything glaringly obvious as far as loose/split plumbing goes.

Up on stands tomorrow and have a gander I guess :/

[h100vw]

If you see any boost then the actuator is probably ok, unless the nuts have nearly wound right off? I am really thinking a decent split in a hose, that holds boost, then gives up.

Gavin

[Stuwey]

Wastegate who in the where now? Turbo stuff confuses me greatly.

I can build a hot mini engine though!

[VWindahouse]

Got a boost gauge in the cabin or access to something that can read a code mate?

[VWindahouse]

I'm thinking disconnect the N75 and see if that changes anything boost wise first. How long were the stages? Also thinking sustained punishment could have sent something into safe mode.

[Stuwey]

Gauge, yes. Code reader plugger-inner, no.

[VWindahouse]

Cool, do a couple of short runs with the N75 disconnected and see what boost you make.

[h100vw]

Cool, do a couple of short runs with the N75 disconnected and see what boost you make.

The N75 is inline between the inlet manifold and the wastegate actuator. With it connected the ECU can restrict the boost that gets to the actuator by opening and closing it quickly. This is usually called duty cycle. The higher the duty ( the more time the N75 is closed, maybe think about coils charging/dwell) cycle the less boost to the actuator and the harder the turbo goes.

With lower duty cycle you get more boost to the actuator.

With the N75 electrically disconnected, the line is wide open. The actuator is set to open at 6 PSI. So as the turbo spools and 6 PSI appears at the actuator the WG opens and bypasses the hot wheel, so the turbo slows down. Boost drops and the actuator closes a bit. then this continues ad infinitum.



Here's the Forge actuator on Anthony's billet baby. Yours is the same but made of steel. The 2 nuts either side of the wastegate arm can be moved up and down to set the cracking pressure (6PSI) of the wastegate. So make sure that they are tight. 10mm stubby spanner is the winner for that job. Be careful of everything behind there if the car hasn't been stood for an hour with the bonnet up.

If they have backed off or have disappeared then the WG will be opening early or be getting blown open and the hot wheel getting bypassed, so no boost. This sounds likely to me.

Gavin

The turbo is the other way up, so the actuator is against the firewall. Also, you can see the wastegate flap in the edge of the turbo outlet.

[VWindahouse]

Gav what's APR's valet boost level again? Do you think valet mode could have been accidently activated? Just thinking 3 to 4 psi is even too low for a boost leak??