VIDEO: I'm out of ideas as to why I'm not making full boost. Looking for help!!
 

Im going to stick to the facts and a quick video.

Car ran fine last season with stock K16s and a 1bar tune.

Over the winter I purschased k24/20g billets and 72lbs injectors.

After install and retune the car makes on average only .9 bar of boost even though the tune is for 1.3bar.

Here is what I have done to figure it out.

1- boost leak test. Found two holes in the backing plate that attaches to the compressor housing. Called company who built the turbos and they told me to plug them. It is where the turbo label would have been riveted to.

Test drive after fixing and still only seeing .8 to .9 bar.

2- pinch the lines going to the wastegate actuator's. Test drove the car still made .8 to .9 bar

3- removed line from N75 solenoid. Test drove and car still makes around .9 bar or so.

4- removed n75 solenoid and tested with power and it was fine.

5- used wire to restrict movement of the wastegate actuators. This would mean the wastegates can never open. Car still ran .9bar or so. WTF!?!?!?

At this point I don't know what to think. I'm really discouraged. Decided to do boost leak test again even though I knew it was fine from the last time. The only thing I can think of is the turbos are defective after getting rebuilt but I just thinks the odds of that are slim to none. I could really use some help on this one. Thanks guys!!!

Thinking outside the pressurized area...

1) What kind of exhaust do you have. Any chance the cats have overheated/collapsed limiting flow?

2) At the turbo intake side, is there any chance the inlet pipes are collapsing limiting flow?

Hmm never thought of that. Exhaust is stock modified so doubt the cats melted as the oem cats are good quality but wonder if there is a restriction In the air flow to the turbos as you pointed out. The two inlet pipes look fine but I will take a closer look. Thanks! Exactly the type of suggestions I'm looking for!

What does the dash boost meter read while you are doing the pressure test..

Okay, those are turbo outlets that you're testing from - very confusing! Does sound like one of the turbos is goofed or an inlet issue. If pinching off or disconnecting the hose to the W/G didn't produce an overboost then it seems to me the solenoid wouldn't have anything to do with it. It's holding pressure pretty good though, this isn't a leak. The inlet to the turbo was a good suggestion but if it's stock I can't see that being an issue. How does the exhaust sound? Under boost does it seem to struggle? When is it hitting boost, does it seem really laggy? Wheels spin freely on the turbo? :(

Could it be that the actual MAP sensor isn't reading properly?

Does the car feel like it pulls strong? You would notice 1.3 bar over 0.9 for sure.

If there was a defective turbo, the pressure from one would be leaking out of the other back up through the inlet tract, so it is a possibility.

Is the car mafless? You should be able to run the car briefly to see if both turbos are spinning. Just take a peek in the inlet while the car idles.

datalog it using a durametric and post the log spreadsheet to datazap.me

then post it here and the experts can chime in

OK so after reading this I went out to take a look and this is what the dash reads while doing to boost leak test.

At under 5psi (0.2bar) the dash reads 0.1 to 0.2 bar

At 5psi (0.3bar) the dash reads 0.3 bar

At 10psi (0.7bar) the dash reads 0.3 bar

At 20psi (1.4bar) the dash reads 0.3 bar

At 30psi (2bar) the dash reads 0.3 bar

No idea what this means but it has to be related to the issue right?

Car has stock MAF. I will start it and look at the turbo inlet tonight after work and see if they are spinning freely. The car feels like it is running 0.9 bar and not 1.3bar. It feels no faster than when it had stock K16 turbos and the 1bar tune. If anything iot is more slugish and laggy.

Ya it does seem laggy. Spun the wheels by hand last night and they spin freely.

When you say "if it's stock" are you reffering to the car or the inlets to the turbo? The inlets are stock but the car has new K24/20G billet turbos as mentioned previously.

If the dash gauge read out VS. boost leak test pressure info in my post above doesnt point to the issue I will do this for sure.


Thanks everyone for the help. I have been racking my brains on this one for 2 weeks.

So it holds 20psi pretty solid?

Do you hear pressure in the exhaust? That is a lot for the stock unit.

Also what is the tune requesting for boost?

Hey Sambo,
Ya all that stuff is in the posts and video above.

Holds pressure fine under a boost test. Tune is requesteing 1.3bar.

Im just waiting for people to chime in on my post # 8 which answers YJosephTT's question.

Sorry I skipped over a few details. When you are driving the car doesn't show .9 on the dash? I've never looked at it while doing a pressure test so I don't know that one

Ya that's the odd thing. Driving it shows 0.9bar (when it is tuned for 1.3bar, hence why I started looking into an issue). But when pressure testing all the way to 2bar the dash only shows 0.3 bar. :confused: