Stutter power loss under full boost!

[930guy]

Forgot to mention left the vacuum hose off that used to attach to the BOV forgot to plug it. Will take out again tomorrow and check the AFR's properly. was running around 15 at idle and same at cruising AFR kept restarting under full boost think the contact must be a bit loose. Doh...

[smurfbus]

Pressure test your intake track. Maybe some hose pops out when on full boost. If you use o-ring fittings with the IC's, it's very important that the IC can not lift at all even if you use force.

[RarlyL8]

Was the BOV vac hose connected when you re-tested the old intercooler?
If an O-ring failed you should have found it when the IC was R&R.
Other than being rich on boost is the engine running well and are the AFR's good?
Is this the case for either intercooler?

[930guy]

The vacuum hose was connected to the new ic. I removed the decel valve so forgot to plug hose when refitting old ic. The engine was running nicely before the mod. When I ran with the old ic refitted the afr's were a bit higher but the afr unit was restarting due to bad earth under heavy boost so didn't get a reading under full boost. Intend to run again later with over boost switch bypassed and see what occurs .

[930guy]

Just to follow up the engine runs great with both ic's idles nice and afr's are where they should be give or take. Except under hard acceleration.

[930guy]

Removed the new intercooler and refitted the original one. I have a 1 bar boost spring in the waistgate. 2 test drives now with and without overboost switch connected. First run 1st gear boost cutout at 0.6 bar. 2nd run cutout the same with brand new overboost switch connected. I connected an air supply to the waistgate sensor hose and introduced air, 0.1 bar I could hear air coming from the waistgate. The more air i introduce the more escapes. from 0.1 bar to past 1.0 bar.

[911nut]

You are going to have to inspect the components of your intake system piece by piece for a split or crack. The hose from the compressor to the I/C and as stated previously the throttle body o-ring. If all check out then the crack is in one or more injector blocks. Checking and replacing those will require the removal of the intake manifold.

[930guy]

Just took for another run overboost switch bypassed, same in 1st gear boosts to 0.6 bar but 2nd gear overboosts past 1 bar before foot off gas, will keep boosting until bang i figure.
Have now taken waistegate apart and diaphram looks relatively new with no holes or wear. Although when overboosts feel like its way down on power.
Feeels like it has loads of power in 1st gear until loses boost.

[RarlyL8]

There will be no different outcome until your AFR's on boost are under control.
At 9:1 the engine is drowning in fuel.
I would test your WUR with a hand pump connected to the vac port while measuring fuel pressure.

[930guy]

Reassembled the waistgate and refitted. Hooked up the air line again and had a mate listen under waistgate. Turns out it was leaking air from the gasket between diaphram/spring housing and the cast bit at the bottom.

[oilonly]

You were right in suspecting that wastegate.

[930guy]

Applied some high heat sealant to both sides of the gasket and reassembled. Took her out, first opportunity floored the throttle and lo and behold problem solved.. AFR Full Boost 12.3 acceptable I guess.. Will now refit the asian intercooler and see how that pans out.
Thanks for all the help.

[1SIK930]

I had the same problem with my gasket. You can get a new one from Andial. It's a little pricey for a washer sized gasket, but its probably better than silicone.

[RarlyL8]

So this time the egg came before the chicken? The malfunctioning waste gate was not allowing the engine to use the available fuel so the AFR's plunged to 9:1?
Troubleshooting these things can sure be interesting!

[JFairman]

Go around to auto repair shops and see if any of them have a used old head gasket from a water cooled car in the dumpster.

If you can find one intact and thick enough with enough material you can cut out a replacement gasket from it for the wastegate.