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      02-12-2013, 11:23 AM   #19
Private First Class

Drives: 2010 335i xdrive
Join Date: Jun 2012
Location: N/A

iTrader: (0)

Glad to hear walnut blasting worked.

Originally Posted by kgaler View Post
My X3 and the 135i with Dinan St2 both do that.
Kgaler: I spent 3 hours or so troubleshooting same problem, it popped up the day i got Dinan S2 tune on my 1 series. Dinan explained its normal and they're working on a software update to fix juddering/surging during hard acceleration.

Root of issue per Dinan: stock turbo BMWs have a barely noticeable surge/juddering during hard acceleration (due to some reason I can't accurately recall...something about either fuel delivery or vanos mapping - not hpfp related), when Dinan tune is applied surging/juddering is amplified to an easily noticeable level due to increased power. They said fix (software update) was coming, I waited a month or so and no fix. Went to battle to get money back and tune uninstalled, got around 85% of initial cost reimbursed. Relatively pleased with how Dinan handled it.