skyfox2003

Ok so i know that the link is old news but i don't have the money to upgrade yet. I have a 1992 miata with a 1.6L with an older FMII kit on it (red intercooler pipes, welded downpipe). I have recently installed a new timing belt and had the turbo rebuilt by a reputable rebuilder (for maint. since i just recently bought this car). however i am having trouble with the boost control drooping pressure by almost 2 psi specifically when it goes into closed loop it seems. here is a graph to better explain.
to try and figure out if i had a mechanical leak i disconnected the hose at the actuator and with a very careful right foot did a pull to my boost tgt of 180 ( not to bad huh?
ok so i turned up the wsns and i am all the way up to 170 (about 58% duty cyle up from about 34% before) and still look like this it got better but i don't know why it wants so much duty cyle and i haven't even fixed it yet
all of these screen shots were 200 unit samples
also the outlet on the solenoid is clear of obstructions

if anyone has seen this before even if on another ecu any feedback would help. thanks

blupton

Hi Jeremy,

Did you ever find a satisfactory solution? I'm experiencing similar behaviour with my Link, right after an intercooler upgrade. As boost approaches the target of 12 psi, WGCM goes into closed loop, WG% goes to about 55%, and then WGCM goes immediately back to open loop. Boost drops to around 8 or 9, and doesn't change after that. It's not a boost leak, as I was able to do the same thing you did (disabled the wastegate and got it up to a steady 12 psi with some careful footwork). I was beginning to suspect the bc solenoid.

Got any suggestions?

Thanks,
Bill

skyfox2003

Hey bill did you ever figure out your boost issue i was on a hiatus from tuning my car for a while and still have the same issue that i cant seem to resolve.

blupton

Hey Jeremy,
There's been a lot of water under the bridge since then. I've since switched to a Megasquirt PnP, but in answer to your question, I was able to solve the boost control issues I had with the Link. After upgrading to the newest intercooler, boost control was not working correctly. Apparently, removing a couple of feet of IC piping made it necessary to go back to the manual and start from scratch. (This was FM's advice.) In the end, the following setting changes made the difference: Sensitivity went from 39 to 43, Base Pressure went from 43 to 35, and Overshoot suppression went from 35 to 0. I'm not suggesting these settings will fix your issues, but those were the numbers when we were finished the boost control instructions in the tuning guide.

I now have different boost control issues with the Megasquirt. It works just fine, but boosts more slowly than the Link because boost control goes into closed loop right from 0 psi. With the Link I was able to delay closed loop control until it was closer to the target.

Good luck with your tune.

Bill

skyfox2003

so the megasquirt doesn't have a spool/boost assist function? i was thinking of going with a megasquirt how do you like it?

Braineack

iTrader: (62)

Going into close loop at 0psi means nothing. The code should keep the valve fully closed as you're building boost until you're within its means to control the boost level. Especially if you're using the boost reference tables where the DC% should be at 100%.

Sounds like blupton just doesn't know how to tune MS ebc.