Tial External Wastegate - Overboosting issue

[Haywes]

Hey guys,

I've done some searching on here and generally on google and can't seem to find anything super definitive as there's a couple of factors, so i'm hoping someone on here might have some solid ideas;

Issue:

I'm running a Profec B Spec II EBC, and a Tial MV-S external wastegate on my 6Boost mani and GTX2876r. I recently had the car remapped (Nistune @ Horsham Developments) and after that the wastegate started opening itself way too early, even with the EBC set to 1.4 bar. I took the external WG off and changed the springs inside, as I read the exhaust pressure can open it early if you're using a weak spring with an EBC. Turns out the spring inside was a 0.3 bar spring, so I changed it out (which cured the initial problem) for the combo Tial recommends to make 1.2 bar and would set the boost controller to do the rest. With the EBC turned on it would spike massively (2 bar or so) - absolutely shat myself so I turned it off and ran it without so as to not damage anything, and just running off of the wastegate spring pressure it would hit about 1.5+ bar, even though there's just a 1.2 bar spring combo inside.

I then changed the spring combo again to make 0.9 bar. It did drop the boost without the EBC but it still does the same thing with the boost controller turned on - spiked to about 1.7 bar for a split second, so I switched it off again and ran it off of the wastegate spring pressure; with a 0.9 combo annoyingly it'll sit at around 1 bar for a while, so it is opening, but then creep up to about 1.3+ bar quite strongly as the revs get higher? The wastegate is a few years old I think, but seemed ok inside when I had it apart.

I'm a bit lost - EBC is plumbed in correctly, no issue with pipework and lines etc. Could the solenoid be faulty on the Profec? And even if that is the case, does anyone have any ideas why it might be overboosting with lower rated springs inside the wastegate?

Like I said, I've done a search around and couldn't find anything concrete, so if anyone has any ideas, even if you think it's simple, throw it out there so I can check it out!

Spec if it helps:

- SR20DET, Nistune
- GTX2876R, 6Boost Mani, Tial MV-S 38mm, External pipe
- Greddy Profec B Spec II
- Tomei Poncams
- 1000cc Injectors
- Fujitsubo Legalis R Exhaust

Cheers

[R3K1355]

Sounds like two problems, I'd get the wastegate sorted first.
Get it to hold a bar or so without creep, then look at whats going on with the EBC.

[speedingmofa]

Isn't there an offset/ratio setting on the EBC to counteract this sort of behaviour?

[autosri]

Try a new boost gauge would be my first test

[ANDY black s13]

only one I can think of is the position of the external gate on the manifold in relation to the flow of exhaust gases can affect how well it vents
if the exhaust has to make a sharp turn (for example if the waste gate feed tube is at 90 degrees to the manifold flow) to enter the gate it will
limit how much it can vent or get rid of excess exhaust drive, some pictures in this linky may explain my idea better
http://www.superstreetonline.com/how...e-positioning/

your's reads as it can vent ok at lower boost levels/less exhaust volume but it's struggling to vent enough at higher boost and causing the spikes and over boost
bit strange how none of this showed up when it was being mapped, has anything been changed since that mapping session other than 'gate springs?

[autosri]

Are all the vac lines sealed okay not split or anything

[green_rs13]

Try a new boost gauge would be my first test

the profec B displays boost levels, im guessing he tapped it from a different source to the actuator.

[autosri]

I’d still try a different boost gauge as the transducer may be reading

[Haywes]

the profec B displays boost levels, im guessing he tapped it from a different source to the actuator.

I’d still try a different boost gauge as the transducer may be reading

I've got a good aftermarket boost gauge on the pillar, as well as the Profec, which reads the boost and logs the peak etc so I can check it back - they both read the same so there's no issues with the readings. It's also clear from how the car sounds and reacts etc. Both have warning alarms set up. Also no issues with the lines etc that I can see/find.

Sounds like two problems, I'd get the wastegate sorted first.
Get it to hold a bar or so without creep, then look at whats going on with the EBC.

That's what I'm trying to do, but the first issue I can't tackle is why the wastegate setup is allowing it to hit 1.3-1.4 bar with only a 0.9 bar spring combo. Just trying to gauge as many ideas as possible.

Isn't there an offset/ratio setting on the EBC to counteract this sort of behaviour?

Well the EBC should be stopping it from going above the set boost of 1.4 bar, which it did with the 0.3 bar spring in (but it kept opening way too early, around the time it came out of vac and into boost, but only slightly), and the % and gain etc was all good, but as soon as I've put any higher rated springs in the boost controller doesn't seem to be able to react quick enough or something, as it shoots immediately up way past that, and it spikes to aggressively I don't want to risk trying it over and over. There's no setting to specify between external and internal waste gate on the profec, I've heard there is on others, but I'm pretty stumped as to why it's doing this now.

only one I can think of is the position of the external gate on the manifold in relation to the flow of exhaust gases can affect how well it vents
if the exhaust has to make a sharp turn (for example if the waste gate feed tube is at 90 degrees to the manifold flow) to enter the gate it will
limit how much it can vent or get rid of excess exhaust drive, some pictures in this linky may explain my idea better
http://www.superstreetonline.com/how...e-positioning/

your's reads as it can vent ok at lower boost levels/less exhaust volume but it's struggling to vent enough at higher boost and causing the spikes and over boost
bit strange how none of this showed up when it was being mapped, has anything been changed since that mapping session other than 'gate springs?

Nothing else but the gate springs have been changed - I wondered if it was potentially possible for the EBC solenoid to get damaged in some way, and maybe this could be why it's not working correctly? I think at one point the COM and NC lines got put around the wrong way and tested - maybe this could have damaged the solenoid? I thought they might be a little more resilient than that though! Thanks for the link, too, I'll have a good read through. It's a 6Boost manifold and they're supposed to be really well designed, so I certainly hope the manifold isn't to blame, and the fact that it ran ok (besides the gate slightly opening way too early) before the spring changes suggests to me that shouldn't be an issue.

Thanks for all the feedback so far guys, hopefully I'll find the answer!

[autosri]

What’s it like after the wastegate and is the wastegate leaking boost into the exhaust via the stem ?

[piman2k]

Can you remember what colour the springs are in the wastegate fitted now?

[BLAKTOOTH]

only one I can think of is the position of the external gate on the manifold in relation to the flow of exhaust gases can affect how well it vents
if the exhaust has to make a sharp turn (for example if the waste gate feed tube is at 90 degrees to the manifold flow) to enter the gate it will
limit how much it can vent or get rid of excess exhaust drive, some pictures in this linky may explain my idea better
http://www.superstreetonline.com/how...e-positioning/

your's reads as it can vent ok at lower boost levels/less exhaust volume but it's struggling to vent enough at higher boost and causing the spikes and over boost
bit strange how none of this showed up when it was being mapped, has anything been changed since that mapping session other than 'gate springs?

It is 100% this. Poor manifold design. Same thing I had after switching from a Greddy manifold to a 6Boost copy. I tried everything to fix it. New wastegate, new solenoid, new lines, several mods to the exhaust/manifold. Nothing worked. Boost controller off and it's still hitting 1.4+ bar with a 1 bar spring. I've now had a new manifold made with a hypertune merge collector.

"These precision investment cast collectors provide superior boost control through optimal waste gate merge, increased resistance to cracking through one-piece investment cast construction and are a labour saving alternative to collectors fabricated from cut and welded steam pipe."

If this doesn't cure the creep I'm setting fire to the bastard thing!

To add, other poorly designed manifolds get around this issue by fitting the biggest WG possible, this kind of works. The other alternative is fitting two WG's. Again this is not ideal and expensive.

[ANDY black s13]

Great minds think alike the OP's and your WG issues read as very similar, be interesting how the Hypertune collector works out for yours when tested
could be an easier fix for the OP than buying another manifold

[Haywes]

What’s it like after the wastegate and is the wastegate leaking boost into the exhaust via the stem ?

Screamer pipe, exits down the bottom of the car. Always ran fine before and can't see any evidence of leaking.

Can you remember what colour the springs are in the wastegate fitted now?

Black and Blue for 1.2, Black and green for 0.9, as per the chart - http://www.tialsport.com/documents/MVSspc.png

It is 100% this. Poor manifold design. Same thing I had after switching from a Greddy manifold to a 6Boost copy. I tried everything to fix it. New wastegate, new solenoid, new lines, several mods to the exhaust/manifold. Nothing worked. Boost controller off and it's still hitting 1.4+ bar with a 1 bar spring. I've now had a new manifold made with a hypertune merge collector.

"These precision investment cast collectors provide superior boost control through optimal waste gate merge, increased resistance to cracking through one-piece investment cast construction and are a labour saving alternative to collectors fabricated from cut and welded steam pipe."

If this doesn't cure the creep I'm setting fire to the bastard thing!

To add, other poorly designed manifolds get around this issue by fitting the biggest WG possible, this kind of works. The other alternative is fitting two WG's. Again this is not ideal and expensive.

Great minds think alike the OP's and your WG issues read as very similar, be interesting how the Hypertune collector works out for yours when tested
could be an easier fix for the OP than buying another manifold

Thanks for the input guys, certainly something I'll be looking into. The thing that makes me think it might not be this however is how it ran perfectly stable before with the boost controller before I changed the springs? Same manifold, genuine 6Boost, same EBC, wastegate etc - It would boost and hold around 1.4 perfectly before, it just opened slightly at much lower boost which meant it felt sluggish and laggy. This is why I was thinking it might partly be the solenoid. It may have always been creeping before I changed the springs, but as I didn't ever run with the EBC off, the controller may have been rectifying this and making it run stable. I'm taking it all into account though and checking it out.

[ANDY black s13]

if you can try another solenoid just to eliminate that as a possible cause,do a wanted thread to see if anyone can lend you one for testing
or even another known working ebc
I have a hks evc 5 and an apexi acvr being unused atm but neither is compatable with the Profec afaik, a lot use the profec though
if you can post a picture of the manifold and WG take off as curious how it is set up and positioned

[BLAKTOOTH]

I have a spare "Universal 3 Port MAC Electronic Boost controller EBC Solenoid Valve Turbo Car" you could try. It didn't work for me but you never know...