Not hitting Target Boost, single Turbo setup.


Mar 22, 2018
R91 335Xi
Hi all. I am having issues with my single turbo setup not hitting target boost. I am on map 2 which should be 17 psi but I am only getting 11 because of my wastegate springs (11 psi)
I did boost leak test and I did have a lot of leak because i changed my 4 O2 senors trying to fix fuel trim issues so took a lot of things off and put them back together. However after installing 4 new O2 sensors in realized that my valve cover had hair line crack in it so that is what caused my fuel trims variations . So I changed my valve cover as well . Fixed all boost leaks and pressurized system to 20 psi all good there.
I am still not hitting boost target. I have JB4 that controls my boost and according to JB4 I can test mac solenoid by having car in any map , ignition on and by pressing gas pedal. I should be hearing clicks from Mac solenoid but I am not hearing anything at all. I unplugged mac solenoid and applied 12 volts from motorcycle battery and solenoid is clicking . I tested wire harness where 2 oem boost solenoid used to connect and I am getting 12 v on wire 1 and 0 volts on wire 2 . Same story with the other boost solenoid wire that is in the harness. To my understanding I should be getting 12v on wire 1 and 6 volts on wire 2. So I am at the loss why I am getting 0 v on wire 2 . I also checked all fused in glove compartment and they are all good. Any one might know what might be the issue?


Changed my Mac solenoid few days ago still same issue. Mac solenoid will not click when Ignition is on , map 1 and pressing gas pedal .
I tried different maps still same boost 11 psi

Anyone know what this might be ?



New Member
Feb 28, 2018
1972 Radio Flyer 90
Hey @BMWPower88 Did you ever resolve this issue? I have been having similar issue after doing roughly the same service/diagnostics as you. Just curious if you ever nailed down the cause? Cheers