* now with dyno sheet *rb25det stock turbo lazy in boost

[metalmulishiaS13]

a little about the car. It is a series 1 Rb25det, greddy intake mani, front mount, stock turbo, safc2(for now), blow through maf setup, 3"exhaust, greddy e-01, amperformance screamer pipe downpipe. Basically I have tried to get my car tuned on two separate occasions and each time, boost comes in real lazy, hovers at about .5 bar till about 5k rpm and then the power drops and then just jumps all of sudden and shoots up till redline. The drop is very noticeable on the dyno sheet. I am not near a scanner today. I will try and get one put up tomorrow.




My thoughts at the moment are either I need a new stock actuator or upgrade to the hks adjustable one for the time being. The other thought is I have heard some things about the am performance downpipe( specificly with the screamer pipe portion). Any help would be appreciated.

[l0nestar]

What values are you seeing for vac / boost at what RPM?

I may have my old 25 WGA.

[l0nestar]

Chart will definitely help too.

[metalmulishiaS13]

vacuum at idle is dead nuts 20-25psi(or 500mg). The vacuum moves fairly well up into boost. It is just a simple mechanical old school greddy boost gauge. Still fiddling with the E-01(disconneted for right now). On the dyno I was watching the boost gauge and the needle and it ever so slightly creeped towards .5 bar, hovered and then the boost just spikes to about .8 bar at redline.


will definitely try and get the chart up tomorrow.

[Krazykouki]

Sounds like you have the SAFC setup wrong. When I set my MAF settings wrong I can duplicate the exact problem your having.

[Kevin.A]

Check to make sure your silicon couplers are tight ,you have no cracks in your welds and your BOV isn't leaking
i had something like this, and it was because i was leaking from one of my couplers.

[mixeds14]

man i would def check for leaks in the piping.. can u take the vac line of the actuator n give it gas slowly n see if u can see a diference in the gauge?.. there a possibility that it may be stickin..

[preston240sx]

my rb20 does that .. i can hear the turbo spooling but i wont be getting any power then all of a sudden it will run like a rapped ape after about 3700 and up....i think its a boost leak but i am yet to find it ....on start up it will chocke out and not wanna run and the vaccum will read 15 ...but after keeping it running it will smooth out and randomly pull a vaccum of 20 -25 mine has me lost too..

[flatrate]

why the blow thru setup

[metalmulishiaS13]

I have my bov vented and I was having idleing issues and I wanted it for if I ever popped a coupler I wouldn't be completely dead in the water.

[Darius]

What is the SAFC doing to your timing at 5500 rpm? Anything?

Dropping 50% of power at that rpm indicates something is either bleeding off boost or reducing timing. AFR's don't look too bad through there, so I'm leaning towards a timing issue. Then again, you're probably running in closed-loop so the ECU could be pulling fuel if it sees it getting too rich from a boost leak. Who knows? Check for boost leaks first, then check SAFC settings and see where that gets you.

[Carl H]

if in blowthru configuration make sure that the maf has not been blown apart...doesnt take much boost to separate the housings.

[metalmulishiaS13]

Possible update, I was having some exhaust work done and while having it done. We found that the wastegate actuator was frozen open. I don't know if that will be the whole problem, but I will try and get an adjustable one here soon and give it a whirl.

[Sil240]

Darius the SAFC doesn't affect timing.
Only Fuel.

Yeah that stuck actuator could definitely be the problem.
Get a RB20 actuator, its set for 10-12 psi compared to the RB25 which is like 7 i believe.

[l0nestar]

Possible update, I was having some exhaust work done and while having it done. We found that the wastegate actuator was frozen open. I don't know if that will be the whole problem, but I will try and get an adjustable one here soon and give it a whirl.

If you want a stock 25 WGA to test. GIve me your address.

[metalmulishiaS13]

I would like to buy someone's old 20/25 wastegate actuator sinceI have a track day coming up.

[l0nestar]

See previous post.. PM me your address and .. $20 for the WGA and shipping and it's yours. I'll get it out tomorrow.

[l0nestar]

Enable PMs.

[metalmulishiaS13]

Done, sorry about that.

[julio]

Darius the SAFC doesn't affect timing.
Only Fuel.

Yeah that stuck actuator could definitely be the problem.
Get a RB20 actuator, its set for 10-12 psi compared to the RB25 which is like 7 i believe.

SAFC manipulates the MAF voltage, which changes TP value in order to change A/F (injector pulsewidth). Timing is also calculated from the TP value, there fore SAFC changes the timing. Pretty sure anyways.