thanks for suggestions everyone.

winigt2... thank you. i REALLY hope they forgot to put that in. will be an easy fix. thank you!

 

Something is really off... you need to do the boost leak from the turbos...

 

swapped diverters, it's not the issue.

AP TB check valve was installed but not sure if it's on reverse or broken.

will try boost leak test from turbos. so i know where to pay attention for leaks. can someone explain how boost leak testing from the turbos and not the MAF location is different, appears it would bypass where the inlet piping plumb into both diverters and oil box on back. but the diverters are ok, and the only other hose goes to oil box. seems if I did it this way, air would back out of the oil box and into the inlet?

May try tapping vacuum source directly from the Y pipe T'd to both actuators as dan suggested.

what about bolting the k16s back on and trying to see if car can boost?

thanks

 

Hi Magnus,

If you don't fancy running with locked wastegates then just remove both pipes form the actuators. Block them off temporarily. If you have set your actuator rods to standard your turbos will boost to the max that the standard actuators will allow. Guessing 1.2 bar . If you are a little hesitant them back the rods off a bit more. You can get boost from a turbo without the pipes connected to the actuator. All they do is retard boost not give it. Its for boost control from the DME or on an older car from a manual bleed valve system.
Just remember to raise the boost with caution when on the road using the gas and load the engine . Avoid WOT there is no need if you get some decent boost. The wast gates will open under exhaust pressure alone when the wastegate back pressure equals or is greater than the spring pressure tension set by the threaded rods in the actuator. You have effectively removed the computer control of the turbo.
If you don't get boost you have either duff turbos or a big leak. It doesn't matter what programs, injectors or timing you have it will boost. That's just what turbos do. I'm not saying there not needed to the contrary but all you want to see is some good boost. Stop go home and put things back as they should be. Use common sense dont over boost keep the revs down and dont get too greedy stop trying . Boost is Boost , if you see plenty of it then job done.
Frank

 

Maybe putting the stock turbos back on will help you eliminate anything else. If they boost it may be a good time to have the 28/18s checked out.

Sorry you're going through this! It's so frustrating.

 

guys... thanks for helping out. Think may have found the problem. In looking over system diagrams to see where leaks or broken valves may have occured, I found they've reversed the n75 hoses! the one that goes to the diverters have been switched with the one that goes to the Ypipe. Dan suggested boost solenoid connection error a week back but I didn't think they would have gotten that wrong. I'm out of town so can't give it a try. Think this may be it?

if so, could the valve been damaged connected this way? thanks!

 

Sounds like the problem and it shouldn't cause any other problems or hurt anything...basically the waste gates are NOT getting the signal to close and allow boost to build...

 

almost fixed...

tested the car today with n75 hoses swapped. Made a big difference. car can hit 0.7bar @WOT 3rd gear around 4kRPM thru 6.5k RMP. consistantly and hold. (it used to hit inconsistantly 0.6 then fall off and hold at 0.4bar - WOT AFR look OK) Lots more pick up on low end but stock gauge appears to lag actual boost. Can feel boost come on, gauge still at 0bar, then catches up. So reversed n75 connection was definitely the or part of the problem.

want to try adjusting the actuator rods but not sure if that will help given the following. plus don't want to use this to compensate if the core problem is elsewhere: All things equal, if previously, the stock turbos/stock actuators could hit 1bar, why can't k2418g turbos/stock actuators do so now? The current k24 DME flash should have an even higher boost threshold at 1.2 vs previous k16 flash at 1.0...both should be telling the n75 to bleed off more pressure. or am I missing something?

thanks!

 

... just remembered something. Would a tune provision for a 1bar WG, and thus affect the rate of bleed the DME signals to the boost solenoid? ie allow more pressure to remain on the actuator to compensate for harder spring thus forcing the stock wastegates to open sooner?

thanks!

 

Are the wastegates larger diameter on the K24 18g than the standard .If so perhaps they are being pushed open with pressure/force from the exhaust gasses and the standard springs are not up to holding back that amount. Same principal as the larger the surface area of a piston ( say in a clutch cylinder) the less pressure required to push it open?
Just a thought.
You might be right/ might not about the DME control and your tune, but I am used to setting up turbos using the actuator rod and a manual bleed valve. I know the n75 has a 75% duty cycle and normally just winding up the boost on the rods wont increase the actual boost as the dme will just compensate and allow more pressure to the actuator and open the wastegate more to drop the boost again. BUT if your tune lets the dme run 1.4 bar then it should only shut down the boost once it gets to the desired level. I would have thought the n75 would not have to do much boost reducing until the boost level reaches the tune level?? Of course there are many other control functions in the dms that control boost . unlike my older cars that would boost to the moon or explode the dme is too clever for that and assesses lots of factors before letting the boost go the desired tunes level. The way I was told simplistically is that engine has to ask the dme if it can boost to the desired level, if all things are in order it, not you. will allow it.
Don't know how this helps though.
I personally would like to know if the Watergate's were larger as the standard actuators wont stand a chance if they are.
Perhaps it would be best to fit the proper wastegate actuators for your turbos and see what happens.
Good luck
ps I still haven't got my alternator checked. Seems to be loads of advice some saying cables etc.ah well different thread.
Frank

 

hi frank. yes i thought about that for the flap size. pressure is same but volume/surface area larger and more force. my exhaust is on so I can't answer that but may be experts can chime in. so in this case, if it were to be true, air pressure x increase in flap area = an aggregate pressure at least larger than the 1bar that the stock actuators held on stock turbos. but from what I've gathered, others have run same k2418g turbos with stock actuators with out same issues Im experiencing.

regarding the DME. have no idea how it works in earnest. my guesswork tells me that the tune may have to compensate for the higher spring rate or the rate at which the flap will move. with a harder spring, a higher pressure is required not only hold the flap but in addition the velocity/speed at which this pressure is to released into the actuator, must be greater in order to prevent over boost (since the 1bar WG is operating closer to the 1.2 bar limit versus stock which starts to open at 0.35bar). but after reading your comments,
appears the velocity/speed "threashold buffer" theory breaks down. the DME should be able to reach target boost value nonetheless (or at least 1bar) as long as sufficient durration of WOT/load is provided. again, guessing, running up to 6k rpm WOT on 3rd gear should be enough for this. "threshold buffer" if true, would only cause non linear boost levels on the way to target or wavering boost at max target. still raining here so havent had a crack at 4th and 5th but doubt it would yield better results.

the 1bar WG's are on the way but i have a nagging feeling it's not just the WGs.

will do another boost leak, pressurized from the turbos this time but need to rig up a few plugs to do so. not sure what this method is supposed to show as compared to pressurized MAF location. but doing so does isolate the inlet piping... which plums to both the diverters and the oil tank. i guess doing it this way creates a one way pressure stream.

on your alternator troubles. will post on your thread

 

good work...

 

LOL ... it's not fixed!

 

i feel like I've won a fight with a tiger...


Turns out it was three things:
1) reversed n75 connection
2) disintegrated vacuum hose between TBplenum and air switch under diverters
3) stock wastegates

Got 1.0bar spiking at 1.1 which sounds about right for stock actuators. Hopefully 1bar WG's and 1.2bar will help the lag and feel a lot faster. to be honest, i had expected more. 1st and 2nd gear hardly build boost unless WOT. thanks for everyone's comments and help. I can rest easy tonight.

 

Brilliant.