buck issue

[shark_22]

Hi, we have some bucking issue with my vems and its hard to find the problem, so if somebody already experiment something like this or have an idea of the cause, will be appreciate to have your help!

It happen at different throttle position, always the same duration but different intensity(depend on the throttle). Never 2 buck at the same time, its one after the other at different moment.

Its like all 6 injector ou all 6 coil stop at the same time. No trigger error, nothing special in the trigger log/log.
 
I re wire the hole grounding system like vems want,re wire the crank and cam sensor just to be sure, and still the same problem.

Its hard to see it on the log, I got one that i provide where we see it at the end(rpm drop and goes back,same throttle pos.)


http://vems.hu/vemstune/sharingcenter/reports.php?cmd=view&key=LkAsIU

Engine:subaru h6 ez30r avcs-vvl, tuned and run very well (but got the buck issue!)

thanks

[gunni]

It doesn´t seem like a VEMS related issue

You might have a problematic ignition relay or fuel injector relay depending on how your car is wired. I would put a multimeter on the 12v on the injectors and see if you loose 12 when the bucking happens. Same for ignition

[fphil]

Indeed I see fast rpm variation @2:44.490 that I cannot understand
2420->2140 in 47ms etc ..  (at that time the variation of Ignition map is quite large)

[shark_22]

Indeed I see fast rpm variation @2:44.490 that I cannot understand
2420->2140 in 47ms etc ..  (at that time the variation of Ignition map is quite large)

exactly,this is the buck. We already check with other 12v source and still the same issue.
The buck can happen at different rpm not only the one in the log.

[fphil]

you may try the last fw version?

[VEMS]

Hello Jerome,

I would advise you to upgrade your firmware from 1.2.25 to 1.2.31 many developments have been done in that time that might benefit (diagnosis of) low toot count triggers.

Best regards, Dave

[shark_22]

Hello Jerome,

I would advise you to upgrade your firmware from 1.2.25 to 1.2.31 many developments have been done in that time that might benefit (diagnosis of) low toot count triggers.

Best regards, Dave

We upgrade to fw 1.2.31 and no more bucking issue:) We manage with this issue since days one!
Im gonna do more testing but for now look like its work well!

thanks