[RMUNOZ]

Hello Everyone,

Long time lurker, first time poster.

The title says it all. I am experiencing hesitations during higher RPM and nobody seems to be able to figure out what exactly is causing the hesitations from the dealership to independent tuners/ Indy shops.

The car is a 2014 428 XI.

So I got the car with 23K miles from BMW Minnetonka up here in Minnesota. The car drove great and I had a ton of fun with it for the first couple thousand miles but eventually I just needed more so I caved and got a JB+ piggyback tune. The tune was great and gave the car the extra power it needed to be light on its feet. Drove for a couple more thousand miles with it, no problems.

Finally I caved to the mod bug and installed a catless DP and got a custom tune from Eurocharged and my god did the car feel great. However after another couple thousand miles I started to get very sporadic RPM fluctuations during start up, especially on cold mornings. Eventually I started experiencing full on hesitations in power during WOT so to play it safe I took off the tune and went back to bone stock.

The car seemed to be doing fine so I put the JB+ piggyback tune back on and the car hesitated during WOT pulls again. All of this and it never threw a code. So the first thing to check was spark plugs. Got them changed out at 40K miles and gapped to stock plug gap. Still experienced hesitations but now at lower RPMs instead of high. Re-gapped my plugs to .022 and the hesitation shifted from low RPMs to high RPMs again. Got my coil packs checked and they were fine too according to the tuners and BMW dealership.


Eventually I went back to bone stock but then experienced very slight hesitation during WOT pulls. Not many but from time to time it would occur. Finally I checked for recalls on my car and there was one for failing HPFPs which BMW did not honor since my HPFP was technically "not failing". Went online and bought a new HPFP myself and installed it and the hesitation went away slightly but sometimes is still there. BMW dealership also checked for leaky injectors and they said they couldn't find signs of them leaking.

So if it's not the plugs.
If its not the HPFP.
If its not the coil packs.
If its not leaky injectors.
Then what could possibly be making my car hesitate?

I am getting a stage 1 custom tune from Eurocharged re-installed next week to see if the JB+ is the culprit but I doubt it.

Does anyone know if the OBII port can be used to read AFR and Boost? And if so does anyone have any suggestions on an inexpensive tool or gauge to check these? I am really starting to hate my car and I'd really rather not cause in its own way this is still the most fun car I've had and I really don't want to sell it!!! (Used to own a Toyota Corolla and switched to an Infiniti G35)

[JoeyF30]

Have you tried the throttle adaptation reset ??? My car does this from time to time. I'll be getting a BMS Pedal Tuner soon.

[RMachuca3d]

A cheap and easy thing to do that *might* help is to clean your MAF, mine seemed to idle smoother after I cleaned it.

[JayFar]

A JB4 with a connect kit can read boost and AFR even if it's on Map 0 (disabled). What you're describing sounds a lot like what I read on the tuning forums when boost is too high and the car runs too lean. Are you still running a cattless DP without a tune?