Not Holding Boost! Hks 2835 Pro S .87 A/r

[LaurelPWR]

It's been on the dyno twice now and doesn't want to make boost up top while running off actuator.. Boost went from 10psi to zero at 6000rpm so I replaced the hks actuator with a new hypergear 1kg unit and still only made 11.5psi and tapered off to zero by 6500rpm. Then I purchased a turbosmart unit with some extra springs. Installed it with 16psi springs and it actually made 16psi but still dropped off to 0psi by aroun 6500rpm! Tuner then loaded the actuator with 23psi of springs and boost still drops off massively... Dyno is red, green and pink. Ignore the blue and brown as that is some of the old gtrs tune settings just for a comparison....

When it has no actuator or boost connected it spikes right up to 25psi and starts to drop again by 6000rpm .......maybe the Waste Gate flapper isn't sealing properly ...fiik

Ideas anyone??

[LaurelPWR]

Have done numerous boost leak tests and fixed a few minor ones before it went on the dyno the second time and also checked for any leaks around the exhaust and she's all tight!

Motor has been rebuilt 10,000kms ago with arp rod bolts/head studs, acl bearings, treated and prepped rods, Ross forged Pistons, cometic gasket, poncams, new lifters, performance springs, power fc, turbosmart eboost2, gtr itb's, 4 inch hard intake pipe, apexi pod, z32 afm, splitfires, 740cc nismo injectors, walbro 460 pump, hpi turbo manifold, exhaust is a stainless hks 2835 pro s dump pipe into a genuine stainless hpi split front pipe into straight through 3 inch exhaust with no mufflers or cat etc...... Runs United E85

[jiffo]

These things will blow the gate open (big flap offers large surface area)

They need a lot of preload on the actuator although your problem does seem a bit extreme.

Have no experience on E85 so can only suggest you continue with actuator adjustment.

[89CAL]

When you say no actuator or boost connected, did you mean that the boost line is pulled off the actuator so it is not controlling boost?

If so you have a wastegate problem. There is no exhaust restriction if the exhaust is straight through so that wont be the issue. Was it a brand new pro s turbo or did you buy it second hand?

[R31 POWER]

Where on the dyno sheet is it dropping off to zero? Looks like normal boost drop to me.

[hypergear]

Monitor boost pressure before the intercooler, If its showing the same sort of tapering behavior it means the turbocharger is out of puff, but if its showing a consistent boost pressure it means the intercooler is restrictive.

[LaurelPWR]

When you say no actuator or boost connected, did you mean that the boost line is pulled off the actuator so it is not controlling boost?

If so you have a wastegate problem. There is no exhaust restriction if the exhaust is straight through so that wont be the issue. Was it a brand new pro s turbo or did you buy it second hand?

Yeah man no line connected and went 25psi then started dropping... And yeah was old and had been sitting for a while but was clearly unused

[LaurelPWR]

Where on the dyno sheet is it dropping off to zero? Looks like normal boost drop to me.

Hey man sorry forgot to mention that dyno printout is with boost control on! The other above info was all read from Mattys computer monitors whilst on the dyno and tuning was in progress... I don't have printouts unfortunately..

[LaurelPWR]

Monitor boost pressure before the intercooler, If its showing the same sort of tapering behavior it means the turbocharger is out of puff, but if its showing a consistent boost pressure it means the intercooler is restrictive.

Yeah we did that too and same result..If the turbo is out of puff, why would it only get to 10psi on the hks actuator with like 10mm of preload and then drop to 0psi at 6500rpm while running no boost control ... These turbos never drop off like this from what I have seen in many others dyno runs.. Even with a heap of preload on one of your 1kg actuators it wouldn't boost higher than 11.5psi every single time and dropped to 0 just like the others Edited September 5, 2015 by LaurelPWR

[hypergear]

The dyno reading above shown its tappered down to 21psi?

[LaurelPWR]

The dyno reading above shown its tappered down to 21psi?

Yeah man correct. This dyno is with the turbosmart actuator and 3 springs combo that equal 23psi.... The problem is it doesn't actually hold boost unless this spring combo is used! My hks gtrs had a 12psi hks actuator with a small amount of preload and it held 20psi from 3500 to nearly 7500 for the last year and a half

[89CAL]

Well...... If the GTRS did it, and the Pro S wont, then maybe its a problem with the Pro S?

[LaurelPWR]

Well...... If the GTRS did it, and the Pro S wont, then maybe its a problem with the Pro S?

Haha ummm yeah man I'm aware there's a problem... Just asking opinions on here to see if anyone else has had a random problem like the wastegate not sealing or maybe something else

[scotty nm35]

The wastegate not sealing shouldn't make much difference in the top end, most internal gates have issues keeping the boost below 12 or 15psi with the gate wide open, at full noise, once tuned. Of course a larger wastegate has a lot of area and a stiffer spring is required to counteract the extra pressure acting on a larger area of puck.

I would suspect a major leak still, perhaps your BOV spring isn't stiff enough, or the vac line is leaking? Try the coke can trick underneath the BOV flange to rule it out.

When you pressure tested the intake, how did you do it, and to what pressure? Perhaps not pressurising the intake but the intercooler piping only will show the fault better?

[jiffo]

Was the GTRS on E85 or petrol?

[LaurelPWR]

The wastegate not sealing shouldn't make much difference in the top end, most internal gates have issues keeping the boost below 12 or 15psi with the gate wide open, at full noise, once tuned. Of course a larger wastegate has a lot of area and a stiffer spring is required to counteract the extra pressure acting on a larger area of puck.

I would suspect a major leak still, perhaps your BOV spring isn't stiff enough, or the vac line is leaking? Try the coke can trick underneath the BOV flange to rule it out.

When you pressure tested the intake, how did you do it, and to what pressure? Perhaps not pressurising the intake but the intercooler piping only will show the fault better?

I pressurise the whole system from the first joiner after the turbo all the way to the throttles at around 35psi... I also actually pulled each pipe off and blocked one end while fully submerging them in a tub of water. There was a pinhole leak but it was minuscule...anyway the gtrs was running beautifully even with the leaks but all fixed now to rule out any other possibility...

I run a turbosmart kompact plumback bov just the cheap $170 ones... The gtrs never dropped boost off like this

[LaurelPWR]

Was the GTRS on E85 or petrol?

Both man.. Made 360whp on 98 @ 18psi and 400whp on e85 @ 20psi

[LaurelPWR]

I never did find a solution to the strange happenings and never pulled the turbo off to inspect it etc. I've just been driving the car as is from the graph/tune in the 1st post.
Around 6 months ago the car stopped hitting target boost on my high boost setting (25psi) in fourth gear and was on 100% injector duty.. If was however, making full boost in lower gears...Turned out my z32 afm tune within the power fc had somehow changed itself .... An Hour on the dyno sorted the afm out and fixed the flat spots but never fixed or explained the boost discrepancies.

Now, Whilst driving around randomly last night I noticed the cars acceleration felt a lot stronger in a few 2nd 3rd gear pulls I did after exiting the m1 highway... I did a few more pulls from 1st to 4th and monitored both boost gauges (one gets signal from the comp housing and the other from the plenum) 1st gear hit 26psi at around 7k rpm, 2nd went 31psi at roughly 5500-6500k rpm (and as quick as I could look and lift off the throttle at the same time), 3rd did the same as 2nd and 4th makes 24-25psi (which is my target) ..... I couldn't do a solid 5th gear run as road length is limited haha

This is the same turbo that I talk about in the original post ^^ the one that wouldn't make boost without dropping off to 0psi unless I put 23psi of springs in the actuator


What the actual f**k....

Anyone got any ideas ?

[admS15]

It's posessed by satan. All I got.

[LaurelPWR]

It's posessed by satan. All I got.

You may be correct my friend....