120 replies to this topic

[Jimbo]

Are the 2 lines on the ECV in the correct location? If they have been mixed up, the ECV will be arse over tit. 

[Ordex]

Good point also! I will double-check them tomorrow by connecting the wires under the dash

[Jimbo]

Wires under the dash wont tell you much, just reference the hose numbers and 

make sure they're in the correct port.

#5 = Top port

#6 = Bottom port

[Ordex]

Checked all vacuum lines are connected as per Rob's 'improved' diagram on page 1. Connected the wires under the dash and the ECV and ICV opened and closed correctly as they should.

 

While I was doing all this noticed a nasty grinding whirring sound from the front of the engine. Maybe like a bearing on the way out resonating through everything off and on. Have heard it intermittently when idling before but not quite this loud. Couldn't really tell where it was originating using the screw-driver stethoscope method. I'll pull the drive belts off the PS pump/alternator/ac compressor and to try narrow it down.

 

Guess this is what owning a TT Legacy is all about

[LukeFranky]

I hope for your sake's it isn't a big end bearing...

[Ordex]

This evening I ran the engine up to temp and the intermittent noise started as it had before.

 

I then took both the accessory belts off and managed to break the stupid bit of plastic the AC belt tensioner bolt screws into.

After being annoyed at myself I ran the engine for 2 minutes without the belts but there was no noise. I was reluctant to run it for any longer as I wasn't sure how long it is possible to run only on the battery for.

 

I put the PS pump/alternator belt back on and the noise came back but not as loud.

 

My stupid question is could the noise be coming from either the PS pump or alternator because I had previously over-tightened the belt?

[Jimbo]

It is quite possible. If you over-tighten the belts, you can damage the bearings in the pulleys.

Start with replacing the belts. As they age, they harden and can squeal. Hopefully it's just that!


How are you going diagnosing the TT operation?

[Ordex]

When I bought the car the power steering pump was leaking so I took it completely apart and replaced all the seals and o rings.

While doing a clean up of said power steering fluid mess I accidentally got some degreaser in the alternator.

I guess any of those things could be causing the noise but as it got better when loosening off the belt hopefully that's all it is.

The belt itself looks in fine condition, no cracks and doesn't squeal. I'll keep an eye on it and if it comes back I'll run the engine again without accessories.

 

As for the boost issues, I'm reasonably sure everything is plumbed right and talking to a few more knowledgeable people confirmed a turbo shouldn't make a droning humming noise at idle. Also in the back of my head is the fact the mechanic found metal flakes in the intercooler and suspected a dead turbo. So I have bought a replacement primary turbo - VF26. If that doesn't improve things then I'll keep at it, but at least I'll have a more capable turbo.

[Jimbo]

I had thought dead primary, but It didn't click that you might have mentioned parts of it were found elsewhere!

Only reason a primary wont boost is 1) ECV stuck open 2) Wastegate seized open or 3) she's snuffed it

[LukeFranky]

Seems fairly common for the primary turbo to have issues. They do a lot of work.

[Ordex]

I'm still waiting for fastway to deliver exhaust gaskets before I can get on with swapping the primary turbo. No doubt they are caught up in the influx of parcels at the moment!

 

In the meantime out of necessity I've been driving the car to work and back - about 15km with highway each way and a good hill. Issues aside it's such an enjoyable car to drive. Whatever the struts/springs are in it feel low, solid and awesome!

 

Updates on those issues, the boost out of the primary has been fluctuating a bit day to day between 0.8 bar and 0.4 bar - so again hurry up fastway and deliver my parts!

The nasty grinding whirring noise from the front of the engine I investigated previously re-appeared briefly the first day I drove the car and hasn't been back since. Bearing noise from either the PS pump or alternator has gotten louder over the week so replacement of one or both of them will be my go-to if things get worse.

 

Also I hope everyone on here gets the chance to work on their cars over christmas/new years or otherwise just has a good break.

[Ordex]

Christmas Break Update:

 

Pics for attention:

 leggy.jpg   103.85KB   2 downloads

 

Executive Summary:

• Swapped primary turbo - now have VF26 primary and VF32 secondary
• New VF26 works well, boosts quickly
• After initial run in twin mode, primary won't make more than 0.5 bar boost or change over into twin mode even after sitting over night

 

Unabridged:

Had a full day yesterday working on the car. Managed to complete the primary turbo swap and replaced a leaky valve cover gasket. Also fixed the AC compressor belt tensioner so now I have AC again - even in Tassie AC can be nice during summer!

 

The turbo swap went reasonably well - it probably took me the best part of 5 hours going at slow and methodical pace, double-checking everything.

After bleeding the notoriously difficult cooling system as well as possible I went for a test drive. The cooling system made gurgling noises from the heater core and I ignored it. This has disappeared after a few drives so I figure the system must be working as designed.

 

I went easy at first, gradually pushing the primary a little more each time. Even so the difference with the new turbo was clear! I could feel the boost coming on nice and early and the boost gauge was reading up to 0.8 bar without too much effort. All good I thought, so gave it a bigger run and felt the VOD as the change-over onto twins occurred, at which point I backed off.

 

Now here's the confusing part, I was then unable to get the primary to make more than 0.5 bar boost and the car would no longer change-over to twin mode. I did a few more runs like this then took the car back home where it sat for several hours while my friend helped me do the valve cover gasket. I undid and re-tighten the (aftermarket GFB) BOV as I was suspicious I didn't do it up tight enough initially.

 

Once we were done we went for another test drive. Same thing happened as before, primary made plenty of boost and car went to twin mode. After that the car wouldn't make more than 0.5 bar on primary or change over to twin mode.

This morning (after the car sat all night) the primary was limited to 0.5 bar from the first drive.

 

Conclusion:

My own analysis is this behaviour was occurring prior to the turbo swap, but wasn't as apparent due to the old turbo being quite tired. That being said I have yet to triple-check all connections or do any further tests.

Hoping someone can provide a few pointers or ideas as of where to concentrate efforts.

[LukeFranky]

Any engine lights? What could be happening is that the car goes into limp mode after something goes wrong during the twin turbo stage.

[Ordex]

No engine lights so I figured it wasn't a limp mode thing.

 

Today I had the realisation 0.5 bar is wastegate pressure, so I gave the boost control solenoid a clean out with some carby cleaner while the car was in test mode (solenoids clicking, fans, etc). This did nothing (lol).

So I gave the car a run with nothing hooked up to the wastegate and sure enough made plenty of boost easily (about 1 bar).

 

I ran carby cleaner through the boost control solenoid hoses just in case but it didn't seem to make a difference either.

 

Headed out for a drive this afternoon and coming back up a long hill at 80 in 5th the boost needle was stuck at 0.5 bar and the engine struggling a little. Changed down to 4th and all of a sudden I had full boost and hit 1 bar easily and went to twin mode. It continued to work fine for the rest of the drive home (my its nice to experience proper boost on the primary!)

 

Still confused about what could be doing this intermittent robbing of my boost? I think today's "development" rules out quite a few things.

[Jimbo]

How did you go about replacing the secondary turbo? The early Gen2 GT system (and assumably the secondary you pulled out) has a wastegate on the secondary turbo. 

Have you re-routed the bbod lines to suit secondary wastegate deletion, or have you just left the secondary wastegate lines loose?

Sounds like the boost control solenoid is causing things to go haywire. It might be completely dead, though strange it doesn't throw a CEL.

I reckon you should get yourself a manual boost tee to replace the factory boost solenoid and see how that goes.

[Ordex]

When I bought the car it already had a VF19 secondary so there was no secondary wastegate and the BBOD was a total mess from the last guy would had a crack at it - I assume he tried to follow a B4 diagram.

 

I've followed the diagram by Robbks on page 1 of this thread which shows how to delete the secondary wastegate and haven't changed it since.

 

I think you're right it's something electric and not mechanical and I think I'm getting close.

How does the ECU control the BCS? Is it based off engine RPM or is there some other sensor used? I'm wondering if there is a 'reason' the ECU is not applying duty to the BCS - ie there is a fault elsewhere in the system.

 

The BCS itself appears to work ok in check mode (clicks away) and is squeeky clean now I've flushed it with carby cleaner while in test mode.

[Ordex]

New development in this ongoing saga for anybody who has somehow made it this far...

 

Cruising down the highway in top gear gave it some gas to see what it could do. Made pretty large boost - 1.2 bar (worryingly large?) - lifted off and heard a louder than usual blow off sound and then the car got louder! Pulled over and had a look under the bonnet and discovered a hole opened up in the secondary down pipe and exhaust now flowing out into the engine bay!!!

 

Limped the car back home pulling over on the way a few times to check nothing was getting too hot from the exhaust - which surprisingly it wasn't.

 

The only explanation I can think of at this point is a restriction in the exhaust *after* the two down pipes join and the extra flow from the new turbo was too much for it - clogged cat maybe?

I think this may not only explain why I had such poor boost but also the relatively bad fuel economy.

The car is pretty lumpy when starting from cold for the first 5-10 seconds, don't know what that means or if it's related.

 

I'll get the exhaust inspected and the hole patched or down pipe replaced.

[LukeFranky]

Wow.

Do you need another down pipe now? I've got a stock pair from my Rev D but shipping might be a drama. I'm in Armidale NSW.

[LukeFranky]

Another theory I just had... maybe the spot the exhaust blew open was already leaking exhaust gas leading to bad O2 readings?

[Ordex]

Thanks for the offer, however I have a custom exhaust so I think get a new secondary down pipe made up and the rest of the exhaust inspected.

 

Visually both down pipes were ok when I pulled them out to do the turbo swaps, but I guess there could have been a very small fracture.