[x5mad]

Experiencing same. Car also feels underpowered.

Had it looked at, no codes but dealer changed all 4 injectors. Helped for a little while but back again after only driving 1k.

The dealer cars I've driven just feel so much faster. It's real frustrating as I know I'm not imagining it but dealers only go by codes thrown. If no codes there is nothing wrong with your car.

Really need to put this thing on a dyno and see if I can get something to back me up.

I had a loaner 125i and that thing was awesome. No lag, quick to rev to redline and just felt noticeably faster than my 328

[jogologgo]

Originally Posted by x5mad

Experiencing same. Car also feels underpowered.

Had it looked at, no codes but dealer changed all 4 injectors. Helped for a little while but back again after only driving 1k.

The dealer cars I've driven just feel so much faster. It's real frustrating as I know I'm not imagining it but dealers only go by codes thrown. If no codes there is nothing wrong with your car.

Really need to put this thing on a dyno and see if I can get something to back me up.

I had a loaner 125i and that thing was awesome. No lag, quick to rev to redline and just felt noticeably faster than my 328

have you ever tried injection cleaners?

[x5mad]

Originally Posted by jogologgo

have you ever tried injection cleaners?

Wouldn't know what to use. Besides replacing all 4 injectors would be the same thing but better? This didn't help much

[jogologgo]

Originally Posted by x5mad

Wouldn't know what to use. Besides replacing all 4 injectors would be the same thing but better? This didn't help much

there is a thread i hope it helps.
http://www.bimmerfest.com/forums/sho...d.php?t=590791

[bily]

Have you tried a different brand and grade of gas?

[Stubok]

@Dippydo have you seen this thread.

There seem to be various potential culprits, but reading the link posted above it seams a boost leak may be a candidate too.

[Stubok]

Can you tell us how you cleaned your PVC valve?

I would like to give this a clean. I've cleaned my MAF and will run a tank of injector cleaner.

Originally Posted by rustyminded

build up can happen at any miles, I use RON92 where I live and had bms tune since 3000 kilometers, it's not the tune that caused it but boosting the turbo with bad fuel helped with that I faced same as your problem at about 10 k miles( 15 k kilometers) it always happens between 2.5-4 rpm with traction off is the worst.. it used to drive me crazy I contacted BMS I thought the problem coming from the tune but no it's a very bad build up somewhere in fuel system I cleaned up the tank, pcv valve and injectors and now I don't have any hesitation at all , I'm sure it's no other problem. try it if it keeps persisting tell me

[CalCarNut]

Pc valves are easy to swap in some cars. Not sure about our BMWs though....

[whoisthis]

Is it possible to use fuel injector cleaning method (filling up tank with BMW fuel system cleaner plus and speeding) to get rid of carbon build up for Direct fuel injection system. N20)?
I read from somewhere that this method doesn't work for Direct fuel injection system.

[mge92]

Try doing the italian tune up. Run your car in manual and keep the rpms around 4000 rpm and drive for 10 mins like that. It should sort out the hesitation. Also reset the accelerator pedal by putting the car into accessory mode and fully depressing the accelerator pedal past the click point and then hold it for 30 secs. Turn the car off and then start the car it should also help.

[Stubok]

I thought the PCV may have something to do with this hesitation. However I just read the section (pages 18-24) in the technical training doc (http://www.bimmerpost.com/goodiesfor...BIMMERPOST.pdf) and it turns out the PCV is not active during boost. it is bypassed. So doesn't look like the PCV could be playing a part in hesitation in the zone we are all experiencing it in (3000rpm - ie boosted)

[RPM90]

Originally Posted by Stubok

I thought the PCV may have something to do with this hesitation. However I just read the section (pages 18-24) in the technical training doc (http://www.bimmerpost.com/goodiesfor...BIMMERPOST.pdf) and it turns out the PCV is not active during boost. it is bypassed. So doesn't look like the PCV could be playing a part in hesitation in the zone we are all experiencing it in (3000rpm - ie boosted)

That hesitation right in the middle of peak torque sounds like timing pull and/or fuel cut. Both of these are used by the engine control unit when it detects knock. Knock is most common in turbo engines during peak torque development.

There are conditions that can contribute to combustion chamber environments where knock can rear it's ugly head at higher levels and greater intervals.
High ambient temps. Lean atmosphere, such as higher elevations.
Heavy load, such as climbing hills, pulling weight, etc. Lean air/fuel mix caused by dirty fuel injector, low fuel pressure, or some other fuel restriction.
Lower octane fuel.
Combinations multiply the potential.

Make sure you are using the proper octane rated gasoline.

I've experienced fuel cut and hesitation on hard accel in turbo engines due to air leaks in the air charge pipe/turbo pressurized air.

It's also possible to have a faulty knock sensor.
It might be overly sensitive, or it may have electrical problems sending out intermittently errant signal to the ECU indicating knock when there isn't.

You can try fuel injector cleaner if you have high mileage.
But, if you don't have over 50K or more miles I wouldn't go there right way.
Still, a bottle of Techron isn't that expensive to try.

Modern ECU's data log a good amount of information about what the engine is doing such as throttle input, boost pressure levels, fuel amount, air/fuel mix, spark events including misfires, knock sensor events, etc.
Take it to a BMW tech who can hook it up to BMW's ECU readers.
That's where I would start, once the bottle of Techron doesn't work.

[Stubok]

Thanks for this @RPM90.

I have tried the Techron, but that unfortunately wasn't the cure. I only have 10k miles so it was a slim chance as you noted.

From my review of the data I logged (unfortunately I didn't log Knock) it seems as though the engine dumps boost and within a split second also pulls timing. At least that's what I can tell.

I'm on V-Power 93. so don't think its the gas. I've gone to various stations and it hasn't changed the result.

As the local ambient temp has moved up to 100F here in TX it really has started to stutter more. Even with my larger Stepped Core ATM FMIC. So I've put together a Intercooler spray setup so that I can evaporatively cool my FMIC and charge for heavier pulls. I expect to reduce my IAT from the 107F I'm currently getting to closer to 90F when the FMIC is sprayed.

I do still suspect that I have a boost leak, even though I've tried smoke testing (found no leaks), I don't think it shows enough at low pressure (1PSI test) because I couldn't find a leak. That said there are several reports of blown or leaking plastic charge pipes at higher than stock boost. So I have the ER Charge pipes and will be installing them next week. I'm willing to bet the leak in the stock chargepipe I have, only gets big enough to cause the ecu confusion as boost gets over 15PSI. So fingers crossed the ER pipes fix the issue.

I've also already installed my DV+ from GFB so that I can rule the DV issue out.

One other thing I'm going to try is the colder S55-M3 spark plugs, as there have been some reports that the hotter N20 plugs don't like the conditions brought on by the tune. Both engines use the same coils, so only have to change the coils. Those are going in this weekend too.

I'll report back what I find.

[M5SSILE]

Has anybody got anywhere with this? I have a '15 320 with the BMS JB4, and it was sort of noticeable before(without the tune) but with the tune I find it much more likely to happen.

Unfortunately it's not intermittent for me...picture this.

3500 RPM, holding revs, say going through a corner in Sport+ Manual mode, then I punch it...it's almost like it coughs. No CEL or anything like that but I can hear the diverter valve opening and closing like crazy, then all at once it clears up, I get full boost and away I go.

It's repeatable without fail each and every time. Only mod is the tuner, but as I stated, I can deactivate the tuner and it still does it, just to a lesser degree...less boost.

[CalCarNut]

time for M4 plugs?

[CarlosC]

I had the exact same symptoms when I replaced the spark plugs on my 328. Turns out, one of the plugs was bad. Once I replaced the plug, everything went back to normal and I've had no issues since.

[F30RiK]

Originally Posted by M5SSILE

Has anybody got anywhere with this? I have a '15 320 with the BMS JB4, and it was sort of noticeable before(without the tune) but with the tune I find it much more likely to happen.

Unfortunately it's not intermittent for me...picture this.

3500 RPM, holding revs, say going through a corner in Sport+ Manual mode, then I punch it...it's almost like it coughs. No CEL or anything like that but I can hear the diverter valve opening and closing like crazy, then all at once it clears up, I get full boost and away I go.

It's repeatable without fail each and every time. Only mod is the tuner, but as I stated, I can deactivate the tuner and it still does it, just to a lesser degree...less boost.

did you ever figured out the problem? I have the exact same issue

[Maddias101]

Originally Posted by F30RiK

did you ever figured out the problem? I have the exact same issue

Me too, but it is more like this:

when i continue to build up speed in 3th, 4th or 5th gear, the RPM drops from 5K to 3K RPM instantly! even though i am flooring the throttle. And i'm not talking about shifting, it's really accellerating in gear . sometimes it only goes up to 3,5K or 4K RPM and drops slightly, sometimes it goes up to 5,5K RPM without any troubles. on that point i shift.
When the RPM drop i can feel the reduction of speed in the entire car.

I will try to clean all the filters and systems.

[take1step]

Originally Posted by CarlosC

I had the exact same symptoms when I replaced the spark plugs on my 328. Turns out, one of the plugs was bad. Once I replaced the plug, everything went back to normal and I've had no issues since.

I had the same issue when my car was stock and had the JB4 installed. Under initial heavy load the car would bog down and sputter. In my case, I changed the spark plugs and replaced a leaky fuel injector and the problem went away.

In general, for turbo cars running high boost, you should make sure to have colder iridium plugs; which should be gapped to prevent pre ignition, misfiring, sputtering etc.. It really helped in the initial setup of my car.

I’ve also noticed 90C is optimal for water and oil temps in the N20. You’ll see similar symptoms of sputtering and misfiring under heavy load if engine temps aren’t optimal. As @Stubok mentioned above, IAT’s shouldn’t be ignored either and temps above 55-60C WOT should be monitored. Intercooler, Meth can help also.

[ChubbyWilly]

Originally Posted by take1step

I had the same issue when my car was stock and had the JB4 installed. Under initial heavy load the car would bog down and sputter. In my case, I changed the spark plugs and replaced a leaky fuel injector and the problem went away.

In general, for turbo cars running high boost, you should make sure to have colder iridium plugs; which should be gapped to prevent pre ignition, misfiring, sputtering etc.. It really helped in the initial setup of my car.

I’ve also noticed 90C is optimal for water and oil temps in the N20. You’ll see similar symptoms of sputtering and misfiring under heavy load if engine temps aren’t optimal. As @Stubok mentioned above, IAT’s shouldn’t be ignored either and temps above 55-60C WOT should be monitored. Intercooler, Meth can help also.

I was having the same issue with JB4 and after logging it seems that I was overboosting due to high IATs. If I switch to Map1 I don't have this issue.

I currently have my spark plugs gapped to .022 and the car seems to run pretty good even on Map2 (Cold enough here in TX). I will be looking to get an intercooler before summer hits.