Primary Boost Failure Possibilties
 

This is one topic that i have not found much information regarding, probably because its very straight forward. I've always thought if you have zero PSi boost on the primary you either have a boost leak, or a bad turbine...

But What else could cause such an issue? If the restrictor pill fell out or moved or got lost, the turbine would run 7psi yes? If the Precontrol door got stuck cracked open the Turbine would still boost, just very slowly yes?

Any other ideas would be helpful as I have gone from 10 8 10 to 0 0 0 lol.

Car has BNRIII's on it with a PFC. Emissions equipment has been removed.

Turbines look spectacular and have about 1200 miles on them fresh from BNR.

Engine has good compression.

I have used a pressure tester and checked from the Y-pipe coupler to the TB that the whole system holds 20psi without leaking.

I have removed the Ypipe and resealed it and yes the CCN is shut below 4500.

What am I missing?

Oh forgot to mention, I replaced the 1" hoses and replaced the HKS BOV with an OEM Air Bypass to be sure it was not leaking from there...

charge relief closed?

Well im concerned with my primary boost, and it is OPEN as it has Vacuum on it from the CRA valve to vent any prespool below 4500 yes?

Not to mention the Charge Control should be isolating the primary from secondary charges (which as best as I can verify, it is. The CC is closed under 4500).

can you hear them trying to spool or rushing air?

I can hear no boost leak if thats what your asking but I can hear the turbing 'trying' to spool.

Do you have a boost controller? If you do have you tried changing the settings/disconecting it?

Check this link here,, but me personally i would be checking out the charge control actuator im willing to bet its not closing on primary boost build up so you are venting all the boost through the charge releif valve. Very easy to check, start the engine and see if the plunger is pulled in, let me know.




http://www.autosportracetech.com/RX-...leshooting.htm

I already put my mity Vac onto the CCN and forced it shut, and then attempted to build boost at idle as per the manual, and then (with the valve still held shut with manual vacuum) test drove it and no difference.

I have no boost controller other than the PFC built in boost configuration.

I noticed the Precontrol Rod was fairly 'out of spec' per say... dont know if this woudl cause such an issue.

What about the turbo control actuator on the bottom of the turbos,, the arm hasnt come off the lever or something silly like that?

Nah both the arms / rods are attached with the eclip still in place, however I did note that both were 'out ' of adjustment. Which is wierd as they have always operated fine but they have some slop so I will be adjusting this anyways while im here.

"Both" arms: there are 3 total, precontrol, wastegate, and turbo control. You have to get under and look alongside the oil pan to see the turbo control.

Precontol or wastegate problems usualy result in 7-8 psi or way too much boost, not zero.

Dave

Thats what I thought! Hence i've been concentrating my efforts on boost leak. Hmmm

Ok interesting development after readjusting the rods...

The car will run 10psi primary and 7psi secondary (hey thats a start) but ONLY if I bring the car to 2k+ rpm and then let off (to build vacuum is my assumption) and then PUNCH it.

So this leads me to believe that one of my brand new VITON check valves has failed OR the vacuum chamber is comprimised.

Ideas?

switched out the VITON valve with another one.

After the car sat for 1 hour there was no vacuum available at the CRA if that makes any sense...

Hmmm ideas needed

Theres an easy way to check the vacuum chamber,start the car let run for 10 seconds, switch off,, leave for 10 mins then pull the hose of the chamber there should be a loud whoosh of air.

Definatley sounds like a problem on the vacuum side,, if theres no vacuum the charge control actuator wont stay shut when your building boost. (the reason you get boost when jumping on the gas really quick is because once you start building boost the primary boost holds the charge control actuator open in chamber B),,, and the reason you get a low secondary boost is because the turbo control actuator requires both boost and vacuum to operate correctly

You have a problem with either the vacuum chamber or the solenoid that controls the vacuum to the charge control actuator, turbo control actuator,,,
Probably something simple like the vacuum chamber!

Yup lined another 'used' one up to pickup tomorrow! It definetly seems like its a bad chamber.

Can you hook up your Mityvac to the vacuum chamber circuit and see if it holds vacuum?

You may need a tee fitting to do it but this method has helped me many times.

Also you may not want to hear this but I installed viton tubing on a friends FD this summer (from the original run of heavy-wall Viton made by HighTempSilicone) and the stuff has developed a crazy propensity to split open for no apparent reason. The viton in my car has not done that kind of thing as I knock on wood. I've been replacing his lines with silicone from Baker Precision and it's much more durable and easy to work with.

I pulled the whole nest out already and the lines look pretty good, so im fairly confidant they are ok, but i will T into the CCN / vacuum side and see if it holds vacuum

Update:

With Bryan at BNR's help, we were able to narrow it all down to a bad vacuum chamber.

Car runs a nice solid 10 8 10 again :)

Thanks Bryan for the assistance!

You mind letting us know what happen so someone that have the same problem can diagnose it easier?

The car was more or less boosting normally on the primary IF you took the RPMS's up to say 3k first, then let off the gas, then PUNCHED it. If you just tried to ease into it, the CCN woudl stay open and vent all the boost out the CRA.

The Other symptom was when it WAS boosting, it was a 10 8 7 boost pattern.

The problem ended up being a small split in the Vacuum chamber.

Was an absolute bitch to track this down.

How come you are only running 10psi on the BNR?

Need Secondary Fuel rail and larger secondaries. Was running the stockies at to high of duty cycles for my liking.