[AlexGT]

I will very grateful if you guys can help me finding out why my overhauled B48 engine is having a hesitation like bubbling when the the gas pedal is pressed between 900 and 1,100 RPMs? (please look/hear the video).

A very BAD local tuner messed up with the ECU and the excess of boost killed the piston head and rings on cylinder 2, so the engine had to go thru a small overhauling process:

1- Brand new piston head and its rings in cylinder 2
2- Brand new head gasket
3- Took the opportunity to also:
- replace the rest of piston rings (brand new)
- replace spark plugs (brand new)
- replace ignition coils (brand new)
- replace injectors (brand new)

After the car passes that bubbling hesitation, it actually runs better than before it even got that bad tune that killed my piston head and ring. It doesn't have hesitation while parked or while in idle within traffic, no strange sounds and no DME/ECU errors displayed nor they appear while using a scanner (Bimerlink/Carly or a professional mechanic scanner). BUT, that bubbling hesitation not only annoys me but also concerns me a lot because I don't want my car to get damaged again and it's confusing not to find what the actual problem is.

BMW Dealership says: "no errors during scanning nor in the idrive display, we don't know what could be the reason. Our recommendation is to use the car as it 'might be' gasoline dirty residues that are making this hesitation"... I'm no expert, but that is not reassuring to be honest, this is why I come here to bother you for assistance.

Please, anyone that could give me pointers, I will really appreciate it!

[AlexGT]

Nobody?

[njdangelo]

could possibly be a loose or gapped wastegate. Especially if there was an overboost issue in the past. Had a similar issue in an a4 I owned a few years back although my hesitation was most noticeable under the heavy boost loads (ie 4th gear 1800-2500rpm). Brought it to every dealer/tuner/mechanic and got the same responses "theres no codes its fine blah blah". Ended up getting rid of the car but pretty sure what was happening was a small amount of boost was escaping but not enough to throw a code. This would be most present at low rpm as thats when the turbo is trying to develop most of its power before the bypass valve starts to control it.... or at least thats what i'm lead to believe. Long story short, check for wastegate play.

[AlexGT]

Originally Posted by njdangelo

could possibly be a loose or gapped wastegate. Especially if there was an overboost issue in the past. Had a similar issue in an a4 I owned a few years back although my hesitation was most noticeable under the heavy boost loads (ie 4th gear 1800-2500rpm). Brought it to every dealer/tuner/mechanic and got the same responses "theres no codes its fine blah blah". Ended up getting rid of the car but pretty sure what was happening was a small amount of boost was escaping but not enough to throw a code. This would be most present at low rpm as thats when the turbo is trying to develop most of its power before the bypass valve starts to control it.... or at least thats what i'm lead to believe. Long story short, check for wastegate play.

Thanks very much for the pointers man!

[turnsignalslol]

Originally Posted by AlexGT

I will very grateful if you guys can help me finding out why my overhauled B48 engine is having a hesitation like bubbling when the the gas pedal is pressed between 900 and 1,100 RPMs? (please look/hear the video).

A very BAD local tuner messed up with the ECU and the excess of boost killed the piston head and rings on cylinder 2, so the engine had to go thru a small overhauling process:

1- Brand new piston head and its rings in cylinder 2
2- Brand new head gasket
3- Took the opportunity to also:
- replace the rest of piston rings (brand new)
- replace spark plugs (brand new)
- replace ignition coils (brand new)
- replace injectors (brand new)

After the car passes that bubbling hesitation, it actually runs better than before it even got that bad tune that killed my piston head and ring. It doesn't have hesitation while parked or while in idle within traffic, no strange sounds and no DME/ECU errors displayed nor they appear while using a scanner (Bimerlink/Carly or a professional mechanic scanner). BUT, that bubbling hesitation not only annoys me but also concerns me a lot because I don't want my car to get damaged again and it's confusing not to find what the actual problem is.

BMW Dealership says: "no errors during scanning nor in the idrive display, we don't know what could be the reason. Our recommendation is to use the car as it 'might be' gasoline dirty residues that are making this hesitation"... I'm no expert, but that is not reassuring to be honest, this is why I come here to bother you for assistance.

Please, anyone that could give me pointers, I will really appreciate it!

Hello! Sorry for bringing this up nearly two years later but I think I am also facing something similar to your problem. I was wondering if you were able to pinpoint the cause or if you just live with it. Much thanks!