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Tested CV with 12V and blowing through the banjo hose. BOO! When energized the CV did not close the valve and allowed pressure to the WG hose!
Thanks
Mike G.
Mike -- are you sure this isn't the way the CV is supposed to work? Below is a quote from Clark's Garage, indicating that when voltage is applied, the CV allows pressure to wastegate to open it. But I've also read somewhere that Clark's Garage is incorrect (has it backwards), so I'm not sure where the truth lies.
"The cycling valve is controlled by the KLR Unit (Knock Regulator Unit). The KLR receives signals both directly and from the DME Control Unit to determine how the cycling valve should be controlled. The chips in the KLR have a boost limit which comes preset from the factory. When the actual boost reaches the computers preset limit, the KLR sends a signal to the cycling valve to close which allows exhaust pressure to open the wastegate. If the cycling valve fails, loses power, or a problem occurs in the KLR unit, the cycling valve will fail fully closed. In this mode boost is limited to approximately 1.2 bar. This is essentially the boost at which the force of the exhaust pressure will overcome the wastegate diaphragm spring pressure."
Mike -- are you sure this isn't the way the CV is supposed to work? .
The only thing I can say is that there was flow with either the 12V applied or not. So from that I'm assuming the CV has failed.
Originally Posted by zmf
If the cycling valve fails, loses power, or a problem occurs in the KLR unit, the cycling valve will fail fully closed. In this mode boost is limited to approximately 1.2 bar. This is essentially the boost at which the force of the exhaust pressure will overcome the wastegate diaphragm spring pressure."
This sounds wrong because you would want the CV to be open so that the Boost pressure would be allowed to open the WG and keep Boost low. If no boost pressure is allowed to the WG then I would think it would be as if the WG hose was pinched off allowing higher than target boost??
Just tried brand new Porsche CV and it performed that exact same way!!! So...………….. Definitely not the definitive diagnosis at this time for a failed CV!!
Got this form a German Forum. Translated by Google.
The timing valve has no diaphragm, it clocks a piston. The line C-W is always open. Via the piston, the line R is released intermittently to lower the pressure in C-W.
Test the timing valve
You should blow in "R". If the cycle valve is closed, "R" is also closed (almost). The full charge pressure is therefore on the wastegate. If 12V is applied to the timing valve, "R" is open. The boost pressure is for the most part back into the intake area and the control pressure on the wastegate is minimal.
The timing valve has no diaphragm, it clocks a piston. The line C-W is always open. Via the piston, the line R is released intermittently to lower the pressure in C-W.
Well OK then. Think I'll print this out, frame it, and hang it in the garage. Seems counterintuitive at first, but it would provide more graded control of boost level.
RE-tested CV just to make sure and the old CV is fine. New BOV and sealed the throttle shaft. Did a test run still only 1.4 BAR on stock gauge. Hmm! Going to check the boost press with a gauge now. Wonder if the stock boost gauge has a way to be calibrated?
Thanks Mike G.
Last edited by Mike Goebel; 10-26-2019 at 12:26 AM.
Checked boost pressure with crappy Harbor Freight test gauge that has a max press of 10 psi. Looked like about 9 psi max in 3rd gear. Pinched off WG hose, again, and the gauge read 1st-8.5, 2nd-10ish, 3rd-pegged at 10+psi.
What does the vacuum typically read on these beasts?
Checked boost pressure with crappy Harbor Freight test gauge that has a max press of 10 psi. Looked like about 9 psi max in 3rd gear. Pinched off WG hose, again, and the gauge read 1st-8.5, 2nd-10ish, 3rd-pegged at 10+psi.
What does the vacuum typically read on these beasts?
So what level of boost should be reached with the WG hose pinched off? If the boost press goes higher than the boost max threshold, would the over boost protection activate? Is this a fuel cutoff for over boost protection? I did notice that the DME has an aftermarket chip (EURO something) but the rest of the engine is stock.
So what level of boost should be reached with the WG hose pinched off? If the boost press goes higher than the boost max threshold, would the over boost protection activate? Is this a fuel cutoff for over boost protection? I did notice that the DME has an aftermarket chip (EURO something) but the rest of the engine is stock.
Thanks
Mike G.
Most older dme chips are accompanied with klr chips. Which typically bypass the boost protection.
Things to check for if your not building boost.
BOV diaphram leak/ common
intake leaks/ very common
exhaust leaks/ common
wastegate malfunction/ common
turbo malfunction/ happens
I've checked everything but the Crossover pipe and the CAT pipe. I bought an endoscope for my iPhone and used it to look up from the WG pipe into the crossover towards the turbo. Next is the CAT pipe. Are the aftermarket CATs straight thru usually? I'd like to go from the back thru the CAT and see what I can see.
Pic of Crossover
Last edited by Mike Goebel; 11-01-2019 at 01:45 PM.
Reason: Shrunk Pic
If you plug the exhaust and go underneath the car while it’s idling, you might be able to feel or hear an exhaust leak. Best to do it when the engines just starting to warm up.
i had a faulty bov/bypass valve but still achieved some boost. If you can breath through the nipple it is faulty.
10-23-2019 | 01:34 PM
