s2konroids

Basically got a mase GT35R turbo setup screamer pipe, 3inch exhaust etc, that was tuned and was running fine. Fast forward a bit and i relocated the air filter with 4inch pipe to the corner of the engine bay instead of sitting near the block, consisting of a big pipercross filter and 4inch aluminium piping, 6" long and a 90 deg bend all mandrel.

When i fitted this i noticed the car seemed to overboost so tweaked the boost compensation table (running a MAC boost solenoid), right around full spool point of circa 5500 @20 psi i would hear a jet/slight kinda dumb chirp noise car would boost fine and accelerate fine and just put it down to the new cai, noise appears to come from where the turbo resides and WG area but not sure exactly where.

However now suddenly the car wont boost past circa 8psi (8.2 ish), my wastegate has a 7psi spring. The noise above is obviously not present now, i tried to lower the boost to say 2psi but it wont do that i suspect physically its not possible due to the spring, it still boost to 8psi.

Not fully checked but boost pipes, vac pipes seem okay - need to confirm.

I heard a damaged diaphragm in the WG would cause an overboost?

Could it be a bad boost solenoid?

Any ideas what it could be?

s2k manic

I would look at the boost solenoid first as I believe without it you will default to the spring pressure. I would think if the diaphragm failed it would either dump it all or overboost like crazy hope you get it figured out must be nice having 98octane at the pump our fuel is crap had to drop 3 degrees of timing on top due to summer blend

s2konroids

So consider this diagram (far left), i had it piped like this and always have and its worked.

I just swapped over left and right on the solenoid and instead of making ~8psi it will now make around ~10psi, any indications of whats going on or wrong?

s2k manic

have you tried bench testing the solenoid and waste gate should be able to check it all with a small power source and a vacuum pump and compressed air with a regulator I will look through some of my old books from my turbo drag bike days as I had to trouble shoot something similar also I know dsport mag had an article a few months ago on the different boost solenoid setups would think it might be the wastegate body leaking sense only applying pressure to the top increased boost