GTX3071R boost creep/boost spike! Need help!

[MS3 Ventura]

Installed a GTX3071R w/internal WG and 14psi spring. First got boost creep, because I didn't port it I assume. So, I ported it. I followed the various posts for porting and thought that I had it pretty close. Then...

Using a COBB EBCS, I now have a huge boost spike of 25-26psi by 4.5K rpm (target is ~21psi).

Unplugged the EBCS and connected the WG to the boost pressure on the charged side, about 6" after the turbo outlet. Under WOT got boost climbing to 22psi around 6K rpm. Seems like I didn't port enough and/or have some mechanical problem.

Then I took the WG actuator arm off of the WG flapper. Under WOT the boost eventually climbs to 18-19psi by 6K rpm. Not sure what to expect when the flapper is wide open after porting.

I'd appreciate any ideas / help. Thanks

[86AmishMs3]

Originally Posted by MS3 Ventura Installed a GTX3071R w/internal WG and 14psi spring. First got boost creep, because I didn't port it I assume. So, I ported it. I followed the various posts for porting and thought that I had it pretty close. Then... Using a COBB EBCS, I now have a huge boost spike of 25-26psi by 4.5K rpm (target is ~21psi). Unplugged the EBCS and connected the WG to the boost pressure on the charged side, about 6" after the turbo outlet. Under WOT got boost climbing to 22psi around 6K rpm. Seems like I didn't port enough and/or have some mechanical problem. Then I took the WG actuator arm off of the WG flapper. Under WOT the boost eventually climbs to 18-19psi by 6K rpm. Not sure what to expect when the flapper is wide open after porting. I'd appreciate any ideas / help. Thanks

get a catted dp for creep.

[Vader]

Sounds like what mine was doing. Sounds like the way it is reacting on spring pressure is normal, from what I've read/seen.

Do you have an MBC? If so, try it instead of the ECBS to start.

Link - http://www.mazdaspeedforum.org/forum/foru...ml#post1216204

[MS3 Ventura]

Originally Posted by 86azms3 get a catted dp for creep.

Thanks 86. I have a CPE DP with a hi-flow cat. I guess it's not enough to control it.

Originally Posted by Vader Sounds like what mine was doing. Sounds like the way it is reacting on spring pressure is normal, from what I've read/seen. Do you have an MBC? If so, try it instead of the ECBS to start. Link - http://www.mazdaspeedforum.org/forum/foru...ml#post1216204

Thanks Vader. Any recommendations for a good MBC? I'm now using the COBB EBCS so I'll switch over to the MBC and see how it goes.

[Voltwings]

large intakes will also cause "creep." When i had my 3071 IWG with an 8 psi spring and installed my 4" intake i would see a steady 10 psi from it.

[MS3 Ventura]

Originally Posted by Voltwings large intakes will also cause "creep." When i had my 3071 IWG with an 8 psi spring and installed my 4" intake i would see a steady 10 psi from it.

I'm using an Aeros 3.25" MAF (full 3") intake, so I must be experiencing some creep from that too.

[Voltwings]

Originally Posted by MS3 Ventura I'm using an Aeros 3.25" MAF (full 3") intake, so I must be experiencing some creep from that too.

mmm i wouldnt expect that frm a 3" as thats pretty standard size for BT, its typically 3.5" +

[86AmishMs3]

post logs

[MS3 Ventura]

Originally Posted by 86azms3 post logs

Here's one I just did running off of spring pressure only (no MBCS).

[MS3 Ventura]

Here's another log using my EBCS (4th gear). My previous logs were in 3rd.

I also attached porting photos.

[86AmishMs3]

Originally Posted by MS3 Ventura Here's another log using my EBCS (4th gear). My previous logs were in 3rd. I also attached porting photos.

Ok so have you just tried spring pressure and see what happens...ie no boost control. boost source directly to wastegate.

[superskaterxes]

@RichieRichness;

[WhiteWidow]

I know this doesn't prolly help but my boost spikes are from my clutch being too weak to handle the power! I have a new one to install now. It's only if I go over 17 PSI on my gtx3071.

[MS3 Ventura]

Originally Posted by 86azms3 Ok so have you just tried spring pressure and see what happens...ie no boost control. boost source directly to wastegate.

Yup did that yesterday (post and log are above).

Originally Posted by WhiteWidow I know this doesn't prolly help but my boost spikes are from my clutch being too weak to handle the power! I have a new one to install now. It's only if I go over 17 PSI on my gtx3071.

I already have an upgraded clutch/pressure plate. It's definitely not the clutch slipping.

[86AmishMs3]

damn nucka....loosen the preload a lot and start there.

[Navy_Mech2]

Could be that you have too small of a waste gate to run that low boost. My s259 will creep from 14 to 18 on spring pressure but with the wastegate at 1% I hit 23 which was what fuel cut was at and I bent a rod. I have a 40mm WG by the way

Sent by my thumbs

[Tomas]

Yeah that throat is not ported nearly enough,
You also get less boost spikes if you port the throat of the turbo, not just the hole for the wastegate. You need to port the throat deeper at the point where the lower lip on the inner scroll ends and around it. I.e increase the ID of the smallest ID part of the housing. That's the only way you re going to get the ATP housing not to spike. Not only that but you won't be able to run more than 25 psi at 6K with the throat as is due to turbo/ exhaust choke. Even with a 21 psi spring.

[RichieRichness]

I didn't really see a spike in your logs....but more of creep. If you have too much pre-load you will see a quick spike then boost will settle back down.

however,

I would reduce pre-load first like what @86azms3; suggested.

If that doesn't help then you prob need to do more porting.

[MS3 Ventura]

Originally Posted by 86azms3 damn nucka....loosen the preload a lot and start there.

Yeah tried it and got same over boost. Will definitely be porting again.

Originally Posted by Tomas Yeah that throat is not ported nearly enough, You also get less boost spikes if you port the throat of the turbo, not just the hole for the wastegate. You need to port the throat deeper at the point where the lower lip on the inner scroll ends and around it. I.e increase the ID of the smallest ID part of the housing. That's the only way you re going to get the ATP housing not to spike. Not only that but you won't be able to run more than 25 psi at 6K with the throat as is due to turbo/ exhaust choke. Even with a 21 psi spring.

Thanks I'm going to port it again this coming weekend and I'll do my best to open it up as much as possible.

[MS3 Ventura]

Problem solved! Opened up wastegate hole such that it had 0.050" - 0.070" overlap with the flapper. Now holding boost steady at 20 psi or higher boost targets.

[rfinkle2]

Close the throttle plate on it.