410 replies to this topic

[LukeFranky]

Whoa. Didn't mean to cause a fuss.

 

Do you think Luke and others aren't already confused?

- Be weary, I know enough to be dangerous

 

Now before we get too distracted, might be a dumb question but what are your thoughts on my previous post?

Would a generic solenoid with the same functionality work or would the ECU be too picky?

 

Yes, I know the easy answer is go single or flog it off. Not quite ready for that. I hope you don't mind the continued drone of my relentless questions while I keep fiddling and farting around with it.

[natho]

I'm playing with the tune on my B4 - when ECV POS is enabled, both primary and secondary wastegates (secondary being the ecv) are used for boost control, and both have separate duty cycle tables. I still need to play around a little further, but if my understanding is correct, physically bypassing the ECV positive pressure solenoid as previously described would definitely create a big overboost - the map quite clearly has far more wastegate duty on the primary wastegate at the points where the secondary would also be engaged.

 

LukeFranky you say you can't hear the solenoids click. mine all sounded different - some were loud and obvious, others were softer. i blew through each with a spare hose and an air compressor and verified they all worked. i would suggest you do the same if you haven't already. also, the ones with the 'vent' port on them have one of the ports open to the vent when off, and connected to the other hose port when on.

 

i've also heard they can be dismantled and cleaned further but i haven't attempted this myself. might be worth getting a spare BBOD first, if you're relying on the car.

[LukeFranky]

I found a BBoD (thanks nickknack and KONG).

That ECU would certainly help I think. Will the stock tune cope with a silicone intake and pod?

Thanks for the advice natho, but these 3 solenoids wouldn't click whatsoever and I couldn't get air through on any of the lines. They're locked shut. The others all clearly switched and air would flow through them.

[Jimbo]

"I've got a weird mix. Stock primary and a VF13 or VF21, whichever is the secondary of the pair. I blew the primary of the pair and had to rebuild the old stock one. "


Are you able to confirm exactly what combo of turbos you have? What exactly did you "rebuild" and with what...

Was the car already tuned when you replaced them? If you have a VF14 or VF21 either of those could throw the tune out big time, possibly under powering the whole thing depending on the specs of the housings. Either of those are WAY too old to have on your system. VF13/14 combo is of very early Gen2 and the VF20/21 late Gen2. 

[LukeFranky]

Upon realising my stock primary wasn't boosting I replaced both turbos with a VF21 and VF13. The new primary blew from a split wastegate line a few months later.

I bought a rebuild kit of ebay and pulled the old primary apart. It wasn't boosting because of an oil leak into the exhast side which built up and baked on behind the prop and siezed the turbo. Put it back together knowing full well it may not last but far so good.

So I have the stock primary VF3- something and a secondary VF13 I think. I actually still have the original secondary which works. I just never swapped it back.

Thing is, I get the too lean before the secondary kicks in so I'm not sure it is the cause of my grief.

[Jimbo]

Does the secondary have a wastegate attached to it?

[LukeFranky]

Nope. It's pretty much the same as the old stock one.

[LukeFranky]

Here's a pic of them side by side. Clean one is the one on there now. I can install the old secondary turbo if need be, not much shaft play on it.

Attached Files

•  20150324_131421.jpg   150.49KB   2 downloads

[Jimbo]

Yeah VF21 is off Gen2. Bit of a mis-match. Which turbo was on it when it was tuned?

I think we really need to take the tuned ECU out of the equation.

[LukeFranky]

Has had the tune since I bought it so the turbo was added later.

[allpaw4]

Just thinking, there's not an airflow issue with the silicone intake spouts onto the mouths of the turbos is there? There was big differences between the a-c inlet tracts and the d-e ones due to turbo mouth sizes. Just wondering if the silicone isn't clamping down properly on the different turbos you're running.

[LukeFranky]

You would be right if I was running the non-stock primary, but the primary is stock so it matches up. The secondary turbo spouts are the same size.

[LukeFranky]

Given the concern about the non-stock turbo, once the new BBoD turns up I'll put the stock secondary back on.

[LukeFranky]

It just occurred to me... the car never once complained about being too lean when I first got it and the primary was producing no boost. It drove like a typical NA until the secondary engaged. Occasionally up very long hills it would throw up a turbo related code and went into limp mode, but that took a fair bit to trigger.

 

If you guys think the ECU can't compensate for slightly different boost pattern of the other turbo, then surely it would drive like an utter pig on no boost? I'm thinking the previous owner had it tuned for the crapped out primary so he could flog it off to some unsuspecting sod like myself.

 

Lets pretend you have a fully functional B4. How do you think the car would behave if the primary suddenly stopped boosting?

[duncanm]

like a piss-weak 2.0NA with low compression and a plugged exhaust?

 

Given an ecutek tune requires much $$ and is locked (ie: owner can't pfaff about with it), I think that theory is clutching at straws.

[LukeFranky]

like a piss-weak 2.0NA with low compression and a plugged exhaust?

- That's the thing. It drove pretty well. Just like a fully functional 2.0NA. It was nowhere near as quick as it is now, but it wasn't a slow slug like you would expect.

 

Given an ecutek tune requires much $$ and is locked (ie: owner can't pfaff about with it), I think that theory is clutching at straws.

- Fair call.

[natho]

generally the ecutek tunes are an off the shelf tune which may be tweaked slightly for the car. while it's possibly a very bad tune, it should be generic enough that it works for most b4s.

 

on a previous b4 i had an ecutek tune done by S&J and it drove far better than on a standard tune (and made ~160kw). car was otherwise standard.

 

having said that, i wouldn't have thought that the vf21 turbo to be different enough to cause the issues you're having - but anything is possible. I'd really like to see the data log showing the pri/sec wastegate values while it's surging, and compare to a datalog of a stock tune.