BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > Regional Forums > USA - Southwest > Help Please!!! JB4 surging problems 1st gear to 2nd and any gear WOT!!

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      08-05-2013, 10:40 PM   #1
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Drives: 2007 e92 335i
Join Date: Jun 2013
Location: Long Beach, Ca

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Exclamation Help Please!!! JB4 surging problems 1st gear to 2nd and any gear WOT!!

My problem is when I am in any map (JB4 ISO G5) apart from stock it is not smooth like stock.. very lurchy in first and when changing into 2nd it hesitates briefly like a missfire or stall ?? very weird.. I think I need to change the plugs at minimum and possibly coilpack #1 because it had thrown a Service Engine Soon light while I was WOT but then the light went off as I was crusing. I did not stop when the light came on. i just put it back in drive and went the speed limit (45) then after about 3-5 miles it went off and drove normally.
Also at part/low throttle in D or DS (when JB4 Active, I only ever run Map 1 or 5 all I have is DCI) the car has a very uneven surge type feeling compared to when in stock Map 0.

I'm think my solutions could be to change to coil pack one bank 1 (Cyl 1) as well as ALL of the spark plugs
because I went into my mech so he could diagnose the codes because i did have the JB4 check for codes and it did find them.. I didn't know at the time that I could read them without a computer myself..
I was also considering an intake valve clean via walnut shell blasting.
My final thing I can think of to resolve the surging uneven feeling on wot is to update the firmware of the JB4. I purchased mine off the forum so i'm not sure what version it currently has on it. I have the bms cable to be able to connect and update firmware, I just dont have a pc or have the cable connected. Do you think these fixes could resolve the problems I'm having?
I'm not sure if this is your thing or not. or if you just do coding.. any help would be much appreciated... short of sending a log to terry@BMS.

Kind Regards.
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      08-09-2013, 12:44 PM   #2

Drives: 2010 335i
Join Date: Mar 2013
Location: Texas

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I had the same exact issue, surging while WOT in first few gears and surging at 100+ mph when WOT. I would get SES and reduced power lights all the time because of this.

I tried the upper intake cleaning, did not help. I tried replacing the spark plugs, car idled smoother but still the surging was still there. I ran BMW approved fuel system cleaner through the car, still did not help. Finally after 3months of frustration I figured out what it was...

I had upgraded to the lastest software on my JB4 G5 ISO board which requires that you rip two small diodes off of the JB4 board. (instructions should be stickyed around here somewhere). Once i pulled those two suckers off the car is as smooth as butter, have not had one single SES light or reduced power light. From what I understand, the JB4 and ECU are fighting for control over the turbos and causing them to blow off pressure while still under acceleration. When you rip off the diodes you are preventing this conflict from happening. Just my experience, i hope this helps!
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boost, coilpack coil, jb4, plugs, transmission

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