2012 MCS with 88K (but new to me) and completely stock except JB+.

Before JB+ WOT no issues. With JB+, the first few WOT pulls were fine, then it started bucking. I emailed Jon and he suggested dialing it back to 80%, which I did. Still bucks.

He then said to go to 50%, at which point I asked if that meant I would be getting 50% of the gains and he said yes. He indicated there may be something else going on.

Tonight I turned it down to 70% and will check tomorrow after the ECU has had time to adapt (my commute is 1 hr+ each way).

The car drives perfectly fine and is responsive to throttle, it's just the WOT runs that cause issues.

Anyone else ever encounter this? At 50% to me it's not worth it for the minimal gains.

Thoughts?

Greg

 

Yes I've felt that before, have you had any coils replaced? That might be the issue and not the JB+

 

No, but wouldn't that show t times other than just WOT? It's sooth as silk until I hammer down on it and then the bucking begins. It's almost like it's losing boost, then getting it back.

 

Check to make sure your plugs are good and that they are all gapped evenly and correctly.

mQubed Motorsport, Manic Tuning Dealer

 

Do you live in a hot weather area? My friend with a VW GTI was having the same problem with his JB1. The term is "overboost." In summary, too much air at a high temperature is being pushed into each cylinder, and the engine cuts throttle to avoid detonation. Worth looking into. He had to dial back his JB until cool weather comes. I have a large FMIC, so I think that helps.

 

I live just outside Charlotte, NC, so yes, it has been a little warm here(!). I'll start with plugs since I don't know when they were changed last. If that doesn't work then I may do coils, but I'll also see what the cooler weather does for me.


I just hate to have to dial it back more because I really won't be gaining much at all if I go below 70%.

 

I second the plugs, if you still have the stock beru plugs replace with at least the jcw spec. An intercooler upgrade wouldn't hurt either if you can spare the expense.