Weak BOV Actuator?
 

I have a 93 (no TPS) that has been running MSPNP with MBC for quite awhile at 9 psi. My turbo is a T3 w\ an internal wastegate and is capable of producing over 15psi if I wire the WG shut. I thought I may be able to get better boost control by trying EBC. I set it up exactly like the manual says for open loop control. After playing with the dutycycle, I found I had to have 100% in all fields in order to get the boost to max out at 9 psi.

Is it possible that a weak WG actuator could cause this behavior or is there something else that could do this?

is it plumbed like this:

http://www.boostedmiata.com/gallery2...2/IMG_4351.JPG
http://www.boostedmiata.com/gallery2...geViewsIndex=1

Do you have the wastegate adjusted to open to 15psi? Pretty sure you set the diaphram by twisting the rod and it wont open any further than it's set.

did you just ask that and make that statement?!

Brain,

Yes, it's plumbed exactly like that. The feed is from the back of the intake manifold, through the solenoid, and to the actuator. The actuator is a 7 psi unit. I've tested it off the turbo with a bulb and gauge. I don't know if this is normal but I can pull out on the shaft and it will move without too much trouble.

it should take a little effort to pull the wastegate rod out of the actuator, sounds like the diaphragm might be bad.

The settings I used were:

19.5Hz
20
49.8
9.8

increase boost
dont switch

0

99



Make sure you closed loop table it zeroed out and that the output is working correctly, the valve will fail open (wastegate pressure) without power.

Thanks Brain. Those are the settings I'm using, except my ambient pressure is set at 98. The EBC is working because when I started I had all of the DC fields at 20% and had virtually no boost. Once I increased the DC settings, I started getting more boost.

yeah, sounds like you may just need to replace the actuator. There should be effort on the rod pulling it back, and it shouldn't be easy to pull out. When you put it over the swingarm thered should be a little preload; maybe 2-4mm of extension to fit it over.

I just discovered there may be something else happening. It looks like there's a chance that the insulation lining the inside of the heat shield may have been rubbing on the wastegate arm. I'll get a better look at it tomorrow.