SR: Boost spike?

[Ninjabread]

My sr spikes to 10, even 12lbs under WOT (and it stays there, doesnt go back down). It's an s13 sr, with hks 264 cams and a t28, stock injectors and ecu.

Checked a few things out, same situation. I had my boost controller hooked up, so I disconnected that, and ran my vacuum (boost) source from my hot pipe directly to my w/g actuator, same issue.

It even did this when I had my external gate setup, which had a 6lb spring, but yet my boost always went up to 10 lbs.

Maybe my boost gauge is innacurate? It's a defi d-gauge. t'ed off the FPR line.
Maybe my cams are pushing too much air for that small a turbo? (just a theory my friend came up with haha)

I just want to fix this before I go drifting again, and run 14-15lbs and blow something because I run lean.

[fliprayzin240sx]

So wait, what setup are you running now matt? Internal wastegate or external???

If your still running internal, double check the flapper that its not rusted and slightly binding. It could be adding some resistance to the actuator and opens late and doesnt open all the way.

Not alot of people have this issue since its a stock turbo. If the flapper checks out, id change the actuator to another actuator, maybe even change to an HKS unit. If none of that solves the issue, id take the turbo off and mill out the flapper hole bigger...

[240cracker]

i had a simular problem but we have a big difference in set up. i had a small boost leak and the boost controller was showing more psi every few days or so.

[Ninjabread]

So wait, what setup are you running now matt? Internal wastegate or external???

If your still running internal, double check the flapper that its not rusted and slightly binding. It could be adding some resistance to the actuator and opens late and doesnt open all the way.

Not alot of people have this issue since its a stock turbo. If the flapper checks out, id change the actuator to another actuator, maybe even change to an HKS unit. If none of that solves the issue, id take the turbo off and mill out the flapper hole bigger...

Yes, I took off the external gate setup because some welds cracked.

In turn, I had to grind off some welds that were holding the flapper shut. They were where the actuator arm connects to the flapper arm. That caused some of that "bearing" to break away. but I did check and it seems to have full un-restricted movement.

I will check for boost leaks on that line to my gauge.

[tt99ol]

whats your exhaust like
mine used to sit at .5 bar
got exhaust from the head back
now it wont go lower than .8 bar

[bmx22]

cams and t28 with no injecters or ecu, i was runing jim wolf s4 cams and stock turbo and injectors and 10-12 psi and was running lean as hell, plugs where white and took maf readings with volt meter and it was over 5 volts so the maf was maxed..i ended up taking the cams out .how are you running that set up, would like to know.........

[thestreetzking]

once i switched to hard intercooler piping my stock boost went to 9-10 instead of 7

[Ninjabread]

whats your exhaust like
mine used to sit at .5 bar
got exhaust from the head back
now it wont go lower than .8 bar
once i switched to hard intercooler piping my stock boost went to 9-10 instead of 7

Those might have something to do with it.

cams and t28 with no injecters or ecu, i was runing jim wolf s4 cams and stock turbo and injectors and 10-12 psi and was running lean as hell, plugs where white and took maf readings with volt meter and it was over 5 volts so the maf was maxed..i ended up taking the cams out .how are you running that set up, would like to know.........

Ya, I figured that I was probably not running in a safe range... I planned on getting 550cc's, a z32 maf, wideband and a tune, but I'm waiting on some money from my new job.

[Ninjabread]

Oh yea, forgot to mention...

The other night, my actuator arm fell off the wastegate flapper arm because I didn't have the c clip in there. Essentially, my wastegate flapper was free to be WIDE open, did a 3rd gear pull and it was laggy as hell but it finally boosted to 12 psi still.

That's where i got the theory that my cams move too much air...

[slider2828]

How is your idle? Is it solid? Check for Vac leaks as this could lead to spike. Maybe try adjusting to internal wastegate...

[Ninjabread]

Idle is lumpy because of the cams.
Will check for vac leaks later.
I didn't get your last comment haa.

[bmx22]

yea its the cams like i said when i had the cams with no tune it would hit 12 psi and drop to 7 by red line. the amount of air was to great for a stock t25 and i was also maxing out the turbo since you have a t28 its not maxed out but it is forceing higher boost pressure in to the turbo..also i would check your spark plugs and if they are realy white with specks of black or silver on it,i would not drive the car untill you get a tune and injectors,that collor plugs is showing detination which means you are killing your motor and are risking catostrofic engine failure.....

[Ninjabread]

Hmm wtf ... I tested my theory today. Took the wastegate actuator arm off, wired the wastegate open, and guess what ... 15lb + when I got up in the rpm's. My guess is this is indicating that the internal wastegate passage is simply too small to let all excess air go by.

Gotta fix my old external gate setup and put that back on.

t28's suckk.