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andrew85 andrew85 is offline
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Posts: 46
Join Date: Aug 2019
Car: E92 335i
Default Strange Surging As The Power/Boost Comes on - 08-15-2019, 04:05 AM

Hi everyone,

So I am about 3 weeks into ownership of a 2008 335i Auto and working though all its little quirky problems. The car had a JB4, index 12 injectors, miltek catback exhaust, charge pipe and dual cone intakes, aside from that is stock. It does have a case of wastegate rattle if you free rev to 3-4000rpm and let off the throttle.

What i am trying to fix currently is the way it surges as it comes on to power, it's like boost spikes, then dies a bit then pumps the boost in again.

So far, I have fitted new (1 step colder) ngk plugs and gapped correctly. Updated the JB4 to the newest firmware. Installed the latest pump backend flash through MHD (this did improve the surging). The only settings I have really played with on the JB4 are in relation to wastegate rattle. Which I have read can cause this but I'm really having a stab in the dark with adjustments and have tried all ends of the spectrum for menu 10, 11 and 12, with not really a major noticeable change in the rattle, i have put them back close to where they were. The car has had a couple of tanks of BP ultimate through it now and had engine and gearbox oil serviced/filters changed etc.

I will attach a log of a 3rd gear pull in map1. I'd really appreciate any opinions on the log of how people think the engine is healthwise.

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File Type: csv 2019-08-13 23_16_34_Map-1.csv (30.5 KB, 72 views)
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