keep in mind the wastegate pressure is the spring pressure +/- intake manifold pressure as determined by the cycle valve. this means as more boost is created (higher intake manifold pressure), higher exhaust pressure is required to overcome the (spring+increasing manifold pressure) so the exhaust pressure will increase (exponentially?) as boost increases, until redline or ignition cutoff.

My test were done with line to WG pinched off.
Sox

I think that's backwards? Higher manifold pressure opens the WG valve?

Thanks
Mike G.

HA! just noticed the above post was at 9:51!! hahaha not intentional.

Mike G.

Stupid a$%^ sensor showed up dead....
Teach me to buy from amazon.
Sox

that's what the cycle valve is supposed to control.

My understanding is the the CV does not use any manifold pressure feedback? It's just a set duty cycle based on something RPM?, TPS blah blah. All of this stuff seems like circular reasoning to me after a while.

Thanks
Mike G.

Mike The KLR controls the CV based on TPS and manifold pressure.
Sox

Ran the test with shims in and exhaust system checked for blockages and leaks. (Old CV was dead so new CV in the car).
Results:
-max boost 10.72 PSI, @ 3500 RPM.
-The back pressure with the CV controlling the exhaust bypass was max 15 psi.
The log is posted below. Sorry no log for back pressure yet waiting on sensor.
Sox

http://forums.pelicanparts.com/uploa...1580931248.jpg

Pretty close to what the manual states??

Mike G.

Pretty much 0.72 bars boost and 1.02 bars back pressure. 1 : 1.39 ratio.
Sox

As soon as I get the new sensor will run the BP to boost test again. I believe after the 10 psi point the back pressure rises much faster than the 1: 1.4 ratio seen till then.
The turbo goes into "beating the air" rather moving it mode.
My turbo is original and has 250k on it, so it may also have age issues. It turns easily and there is no play that I can tell, but it may be time to get is refurbished or get a new one.
S.K

250k???? Wow!

Yup had it since new in 86'
Sox

Just ran with 3/8 shim. Stock gauge finally hit 1.8 bar at about 4000 RPM then started tapering off pretty quickly. I wonder if its WG bleed off or Turbo charger not being able to keep up with mass flow at above 4000 RPM?

Thanks
Mike G.

I might actually try this as I shimmed the hell out of the WG 3/8" and still not over boosting. BTW won't the over boost protection keep the boost from going too high?


Thanks
Mike G.

Nope the only way KLR can control boost is by using the WG. If you block it off there is no control.
Sox

Need to find out why you are not getting boost.
The k26/6 turbo as used in this car is at its most efficient at car rpm of 3500. The WG even with shims will start to bypass at 20 or so psi back pressure. So with the line to the WG control pinched off, it should not let the BP go over 20 to 22 psi. If there is that much BP and low boost then there is another issue.
As you have checked the turbo for free motion and minimal play...
You have also checked the BOV (which in our cars is really a by pass, and not a blow off)....
Have you checked the pressure prior to the inter cooler ?

I am assuming the first 2 and waiting to see what you get for the test.
Sox
Ps. also to keep you from going banzai on your engine :)

are you 100% certain there is no leak in the intake system? you could try blocking off the BOV to test if it's working properly as that's one component that can bleed that much boost in a hurry.

there could also be some kind of cut or split in one of the intake hoses that allows it to hold some boost and then all of a sudden will bleed air, are the intercooler hoses okay? throttle body hoses? j-boot? there's a lot of places where a small cut or split or even a loose connection/clamp will be hard to detect.

btw, it's safer to first check your intake is all tight and leak-free before focusing on the exhaust, because if you have a leak in the intake there's no way the turbo can ever spin fast enough to make boost so you could accidentally over-spool the turbo and grenade it. ask me how i know (it happened to me).