bebbetufs

I'm curios about how the CV works. I have been told it has a ball that flutters. This indicates to me it builds/bleeds pressure to the WG by varying the duty cycles. Is this correct?

Oddjob

Basically. Its a solenoid that flutters based on the KLR chip mapping to modulate pressure to the WG, therefore controlling boost. Its not actually a ball, but a solid cylinder w/ a spring that when in one position it diverts airflow/pressure back to the j-boot (energized), in the other position it flows to the WG diaphragm (no power, non-energized).

Scott H

I'll add a little more just in case you're looking to upgrade the way you regulate boost:

I want to say some people have hacked the KLR chip to change the mapping and upgraded the MAP sensor in the KLR to understand greater boost pressures. Kind of overkill given the other stuff out on the market now, but in that extreme case, it's adjustable, but not easily (have to burn a new chip every time to change boost or run it through a chip emulator).

There are three choices for controlling your boost aftermarket on these cars:
1) Manual: These are ball and spring mechanisms for single-port and air regulators for dual port operation. Cheap, simple, reliable.
2) Electronic: Some people like them some don't. Features differ by manufacturer and price range. Can be as simple or as complicated as you want.
3) Piggy back: Similar to the electronic but is part of a much larger, more feature rich package allowing fueling and ignition changes among other parameters.

The other part of this equation is a good wastegate. Get either a Tial and adapter plates or Lindsey Dual Port (I'd recommend the Tial or finding someone selling a used LRDP, their price for a new one is a little high IMO).

bebbetufs

Thanks. I already have the LRDP, I'm just contemplating ways of controlling the boost while retaining the protection offered by the KLR.

So when it goes into limp mode the valve sees zero voltage.
I would think this signal could be conditioned to trigger an EBC into safety mode.

Scott H

Which protection from the KLR, overboost or knock? You only lose the overboost protection when switching boost control method, it will still sense and retard on knock. Some piggybacks and EBCs have overboost protection built in that you can set to whatever point you desire.

bebbetufs

Ok.Thanks for clearing that up. I thought that when severe knock is encountered and retarding the ignition is not enough the car goes into a safe mode where the CV remains open to the WG. I thought lowering boost was a way the car controlled severe knocking? There is a lot of confusion to be found on this subject around the forums.

Oddjob

Overboost is on the DME chip. Its a fuel cutout. Its removed on virtually all aftermarket chips.

Knock control retards timing and can cut back boost in small increments if there is still knock after the timing retard. This small boost cut function is lost when using mechanical boost control to bypass the factory KLR/CV system.

bebbetufs

Thanks Jim. This is the kind of information I need.
So what exactly is this limp mode I've read about?

Oddjob

"Limp Home" mode is a protection function of the KLR. The KLR has various diagnostic functions and if it detects a fault in any one of the tested systems, it drops the boost and retards timing.

For example, a faulty TPS or a bad knock sensor can trigger the KLR to go into "limp" mode.

bebbetufs

Gotcha. Thanks.
Do any of the EBC's have knock detection?

Adonay

My vitesse package has a limp mode were the boost gets cut if overboost . Dont know if it read knock from KLR but i think it does.

bebbetufs

I think I've figured out a way to use the CV signal to override an electronic boost controller to pull boost if ignition retardation is insufficient. I'm not sure if it will work in the real world though. I'll post the results.