Reduced power light at WOT

birry335 · 10-11-2014, 09:19 AM

So this has been happening ever since I got my car back from the shop for water pump/ thermo replacement, and VANOS recall...
While my JB4 is on, every time I try to go WOT, I can feel a vibration in the rear, and the car immediately reduces power and the yellow half engine light comes on. The car starts to shake at low speeds. If I turn the JB4 off, or restart the car, it all goes away.
I did some searching, and determined it may be the spark plugs not being able to handle to extra fuel and air from the tuner. So last night, I changed them. Also since getting my car back, there has been this strange vibration or humming coming from the engine bay. After changing the plugs, it went away. BUT as soon as I got out on the road and attempted WOT, I got reduced power just like before.

I used map 1 and 2, and it happened with both. If I go back to map 0, I can go WOT no problem.
The only other theory I have, is possibly something with the DME...
Anyone have any ideas on this?

Johnny Boost · 10-11-2014, 10:27 PM

Well what code is the car throwing when it goes into limp mode? Do you have the USB cable for the jb4?

birry335 · 10-12-2014, 08:25 AM

I do not have the USB cable. I brought it to a shop near me yesterday, it's throwing a P0304. So cylinder 4 miss. I'm gonna change the coil next i think..

10-11-2014, 09:19 AM	#1
birry335 Private 1 Rep 61 Posts Drives: 2011 335i Join Date: Jan 2014 Location: Annapolis, MD iTrader: (0)	Reduced power light at WOT So this has been happening ever since I got my car back from the shop for water pump/ thermo replacement, and VANOS recall... While my JB4 is on, every time I try to go WOT, I can feel a vibration in the rear, and the car immediately reduces power and the yellow half engine light comes on. The car starts to shake at low speeds. If I turn the JB4 off, or restart the car, it all goes away. I did some searching, and determined it may be the spark plugs not being able to handle to extra fuel and air from the tuner. So last night, I changed them. Also since getting my car back, there has been this strange vibration or humming coming from the engine bay. After changing the plugs, it went away. BUT as soon as I got out on the road and attempted WOT, I got reduced power just like before. I used map 1 and 2, and it happened with both. If I go back to map 0, I can go WOT no problem. The only other theory I have, is possibly something with the DME... Anyone have any ideas on this? __________________ 2011 E90 335i JB4-Flex Fuel wires-BMS Intake-Vishnu catless DP-Vishnu CP- M3 Front bumper
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10-11-2014, 10:27 PM	#2
Johnny Boost Colonel 324 Rep 2,014 Posts Drives: '21 M850i GC Join Date: May 2013 Location: TBD iTrader: (0)	Well what code is the car throwing when it goes into limp mode? Do you have the USB cable for the jb4? __________________ WedgePerformance E40 MHD \| Performance Exhaust Mod \| BMS DP \| Vibrant 1790 \| BMS Intake \| VRSF CP \| xHP Stage 3 Michelin PSS \| M3 Control Arms LUX v4 LEDs \| Shadowline Grills \| Lip Spoiler
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10-12-2014, 08:25 AM	#3
birry335 Private 1 Rep 61 Posts Drives: 2011 335i Join Date: Jan 2014 Location: Annapolis, MD iTrader: (0)	I do not have the USB cable. I brought it to a shop near me yesterday, it's throwing a P0304. So cylinder 4 miss. I'm gonna change the coil next i think.. __________________ 2011 E90 335i JB4-Flex Fuel wires-BMS Intake-Vishnu catless DP-Vishnu CP- M3 Front bumper
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