[jamesmurray]

Hi, I'm experiencing an issue where I get a weird surging/oscillation at part throttle when accelerating. The car feels like its straining against itself, however when I go WOT the car takes off. I've managed to catch it in a log (see pic below). If I disable the JB4 it runs smooth on the BM3 back end flash. Any help on his would be appreciated.

Im running on my M240i;
JB4 with EWG
Meth on Map7
BM3 back end flash

Thanks

James

[KnifeEdge87]

Why is your ecu psi higher than your boost1/2 numbers?

[Ke90]

Why don’t you use a BEF from Terry? I am guessing you had BM3 first then bought JB4?

[jamesmurray]

Thanks for the replies. Yes I bought the BM3 first, before adding the meth kit. Am I able run terry’s back end flash without MHD?

James

[Ke90]

No you need MHD to run the BEF, I am not 100% sure but that is his instruction per the BEF support page.

I would wait and see if a tuner responds to it about your options. I have same car and you have like no timing there. I would back off on running car hard until an actually professional steps in to advise, just my .02 cents.

Also, by the look of it can’t tell if you even having meth flow? Try to upload the actually .csv file for them.

[jamesmurray]

Thanks for the info. Terry looked at my setup a couple of months ago, and everything is fine. At WOT everything works as it should, and meth is flowing without issue. The issue above is under part throttle pedal (30-40%), where the BM3 targets 15psi (ecu psi) but the jb4 is targeting little or no boost which is causing the oscillation at part throttle. The .csv is included in the first post. Thanks

James

[Ke90]

Haha! I do see the .csv, my bad man! Also, I didn’t realize it wasn’t WOT. I’m curious to see response and will be following. Hope it all works out well!

[KnifeEdge87]

i too would be very interested in how this turns out, please keep us updated

[KnifeEdge87]

Originally Posted by jamesmurray

Thanks for the info. Terry looked at my setup a couple of months ago, and everything is fine. At WOT everything works as it should, and meth is flowing without issue. The issue above is under part throttle pedal (30-40%), where the BM3 targets 15psi (ecu psi) but the jb4 is targeting little or no boost which is causing the oscillation at part throttle. The .csv is included in the first post. Thanks

James

the jb4 target is an additive target though no ?

surging/oscillation are also entirely different things, it's doubtful you're experiencing surge and the oscillation in boost pressure though noticeable in the figures, don't seem to be extreme (you're going from 9.5 to 10.5 give or take, even on my regular logs i see psi readings fluctuate by 0.5psi from timestamp to timestamp all the time)

again, if you're experiencing something you don't think is normal

it's worth it to check it out

do you have a gopro ? maybe a video would help clarify what you're seeing