vems not allowing boost properly

[diesel des]

Hi guys. I have vems on my aan Audi urs4 stroker. I have been running vems for about 7 years and it mostly runs great. I had an issue about this time last year with boost acting weird and I thought I had fixed it, but it's came back again. Basicly what happens is that boost reduces below setpoint. So say I have 3 bar set as requested so I have 2 bar boost. When the issue happens the boost falls off for no reason to wastgate spring pressure or just over. When this first happened I blamed by boost control valve and replaced it. This made no difference. So when looking at vems screen when this happens the requested boost level stayed were it should but I noticed the duty cycle for the control valve falls off from about 80% to less than 40%.

I can see nothing in vems that would cause the boost to do this. I have no limits set for egt or anything like that so I don't know. What I did the first time was to flash a new firmware onto the ecu. I'm now quite current with version 1.2.20. So now the problem has came back I loaded the 1.2.20 back on again but this made no difference.

The problem dosent always happen, but when it does it's usually when you really want the power so it's a big issue for me. Were should I look to fix this.  Cheers des.

[Kamuto]

that just will be egt or iat values check how boost target changes

[diesel des]

Thanks for your response.  The boost target stayes were i want it at over 300, but the actual falls off to 210 ish.   I have nothing set for EGT or IAT in terms of limmits, at leaset i think not?  I can see the duty cycle fall from about 85% when boost is correct to about 40% when its too low.  Maybe my PID settings are wrong.

I am trying to attatch my map but i cant find the option?

Thanks Des

[diesel des]

Try this link for my config

http://www.filehosting.org/file/details/526607/v3.3_u002860-A-2015.11.29-14.19.19.vemscfg

[diesel des]

Im not sure how else to share this config file sorry guys.

[mattias]

[mattias]

Good reading : http://www.vemssupport.com/forum/index.php/topic,2123.0.html

You have not set up a "refDC table vs boost target" so the boost controller doesn't even know where to begin properly. If the actual MAP reading is too far away from the boost target, the controller will only follow refDC.  You can set these limits to avoid the regulator overshooting target, etc. The integral limit itself will limit how far from refDC you can go, I use way lower values than you have (125, vs ~20).

[diesel des]

Thanks for your input. I had set that boost ref table previously but somehow it has got corrupted as you can see with the odd random values. I opened an old config and put the values into my current setup. I also adjusted the pid settings and now boost is back to how it should be.

This is odd as everything had been working fine so how did that table get corrupted? It seemed to happen after I had been using my laptop to change some idle settings and vemstune stopped working while burning new values. Can this corrupt tables in the ecu?  I wasn't working on anything boost related. Odd. Thanks des.