[phrenetiK]

bought a used 135i with full bolt ons and a jb4. dp, midpipe, axleback, and dual cone intake. car is SLOWER THAN STOCK with all these mods. didn't find this rut until i raced and drove a stock 135i.

getting some lambda codes, i replaced o2 sensors, and spark plugs. nothing helped. then i had the idea to take off the jb4.

boom instantly the car was running great. no more rough idle, boosted correctly, pulled hard and instant torque. that led me to believe the jb4 was screwed up. then we installed the jb4 on my friends stock 135i. it turned his car into a MONSTER. my car should even pull harder than it does with all my supporting mods, however that was not the case. we put the jb4 back on my car and same thing. starts idling rough, only boosts to 3psi 1st 5 psi 2nd, 9 psi 3rd...so slow. also throws more lambda codes. take off the jb4 again and bam instantly making over stock performance.

i have no idea whats wrong but would like to testsomething like a cobb or procede on the car and see if they both cause the car to run ****ty too, or if my car strangely just hates the jb4?

im running out of ideas here and have been at this for 2 weeks now and nothing i try is working.

tl;dr car is faster without jb4 on any map(1,2,5). same jb4 turns friends car into a beast. wtf?

anyone local have a cobb or procede or something we could test on my car for an afternoon?

[phrenetiK]

2C7F Lambda probe behind catalytic converter 2, trimm control
> 2C6A No Description Found
> 2C31 Lambda probe in front of catalytic converter, trimming control
> 2C32 Lambda probe in front of catalytic converter 2, trimming control

per terrys instructions i spent 400 replacing o2 sensors and the codes for upstream o2 sensors are still there after installing the new ones.

the o2 sensor plugin by the bumper is plugged into the downpipe closest to the bumper, and the exhaust side plugin is plugged into the downpipe closest to the exhaust. that is correct i imagine?

[cwarren]

wonder if they are swapped car will run like crap. dont know how bad this would effect the car in stock form though. evryone who has switched them around did it with after market dps.

[phrenetiK]

its my jb4 on his car running fine.

[Terry @ BMS]

2C31/32 have always been the result of a improperly adjusted downpipe fix or related wiring.

[cwarren]

if it works fine on one car and not the other its not the jb has to be 02 related