Hey all, So I had a question.. I have a question about my greddy kit. For some reason, I've been getting boost spikes, highest up to 10.8 psi. I checked all my tubing, and it all looks ok. I put 7lbs of pressure on my wastegate, and it opens up fine.. I'm going nuts trying to figure out why i'm getting these spikes? I'm also running the accessport.
Anyone else have a problem with these on the greddy kit?
Yes, I have mm's Fix #2 as well, wastegate is plumed right after the turbo, on the pipe. . my BOV is attached on the nipped by the UIM.
and my boost gauge and Boost controller pressure sensor (which is off) are plumed by the 2 lower nipples on the lower intake manifold. My boost controller is off.. I even removed it entirely and ran on just the wastegate.
It's driving me pretty nuts.. I don't want any big booms..

 

what is your exhaust setup?

 

welcome to the GREDDY .....it happens alot to greddy owner, but as long as you tune it, it will be fine. just buy the boost controller, which still spike, but at least you can hold it on certain boost, example 11 psi is the highest, you will be fine.
i had it, mysql had it, and he gave me some advice.....so, get used to it, and make sure that your car is tuned right

 

I have the AP.. so, I don't think I can tune it.. lol.
since MM is doing my maps :P

 

I have a turboXS exhaust and racepipe. with silencers in my tips..

 

are you getting this when you get up to high rpms?

If you are then I had the same problem until I switched to the GT3071R. Its basically a problem with the Greddy turbo's wastegate. It cant loose enough air fast enough so it will keep spooling. (I think)

 

that's what i meant, it was the wastegate of greddy that can't hold the boost....

 

do you have the block off plate installed?

beers

 

^good call swoope!

also your boost controller should help with that.

 

I don't have the block off plate installed.

 

I highly recommend it. I did after reading this thread:
https://www.rx8club.com/series-i-major-horsepower-upgrades-93/greddy-turbo-owners-make-sure-you-fit-your-blocking-plate-164382/

 

brettus is way ahead on this. and making it better for everyone..

beers

 

yea i get boost spike up to 10psi after 7krpms,mm told me to go ahead and buy a boost controller and just set it for 10psi so its got a much more smooth curve to 10psi instead of it spiking,also assuming ur afr readings are good too,and i have the blocking plate on,greddy intake,mm ap reflash

 

Well according to Jeff, once you have the AP in there you dont need the blocking plate. That was just a crutch used by greddy since their tuning solution couldnt handle that other port in the intake.

I had it on and as soon as I got my GT3071R I took it out. No problems so far.

 

im aware of that,but i don't have the gt3071r,so ill just keep mine on for the time being

 

The blocking plate does more than just help with the tune . It is Greddys way of making the best of an undersized turbo so you were right not to use it with a larger tubo .

Marcux - can you give more details on this spike . Is it an instantaneous thing as you change gear or more sustained . IE how long does it last and at what revs ?

 

I can recreate it every time.. just seems if I mash on the throttle (WOT), it goes past the 7... if I take it easy, or just before WOT, it'll just hit 7.. It seems to be sustaned.. at the upper rpm limits.. Hypothetically, if my wastegate was locked closed.. what is the max pressure i'd get from the greddy? does anyone know? I'm gonna take it out again, and see what rpm's it does it at.. It's been a bit cold as well recently in NH.. I wonder if that has alot to do with it..

 

Actually, Now that I think about it.. I have my passenger tell me it spikes between gear changes usually..

 

well then - that is normal ........

 

I get spike too...no surprise.

boost set at 6psi...spikes to 10-12psi after about 6K rpm WOT.

I took out my open midpipe and put in my stock midpipe in and that helped to settle things. However when really cold (under 30 degrees...i still got spike...not as crazy though, 9-10psi)

I want to put in a boost controller in to see if it helps with the spiking.

What boost do you guys set the stock greddy wastegate at....as you put in the boost controller. I want to run 10 psi and be able to run my open midpipe again, without spiking.

If anything I will be welding up some piping in the summer for an external wastegate setup....i think that may be the best route to go with....but not something i have time for right now.


let me know guys.

Adam

 

stock greddy wastegate spring is 5psi

 

so you set your stock wastegate at 5 psi and than set the boost controller to the desired need....is that correct??

 

I've done a lot of experimenting with this in the last few days and discovered a problem most people with boost controllers wont even know they have .
Boost surge under partial throttle at mid to high rpm .
You will only notice this if you have your pressure guage on the turbo side of the throttle body. I was seeing 15psi here while the UIM is still in vacuum .

The fix is easy - plug your boost controller into the turbo side of the throttle and not into the uim as most people do .

 

yes but you will still spike, the wastegate on the greddy turbo sucks

 

When do you see the spike ? Between gear changes? Do you have a decent blowoff valve fitted ?