Hello All,

I need some help, I have just changed the coils, spark plugs and wires on my '02 D2 for a hard misfire and after putting it all back together I was greeted with another CEL (P0150 and P0174 - These codes were not there before).
If I erase the codes P0150 comes on after a drive cycle and P0174 with be set as pending.
Frustrated, I became a parts changer and just replaced the 2 front O2 sensors with new Bosch parts .... but codes came back after another drive cycle.
I have started to diagnose it and have been primarily smoke testing the intake to see if there is a leak. After many smoke tests I could not see any leaks, also I smoke tested the SAS thinking maybe they had a leak from me nor properly tightening but could not see anything there either.
I am now stuck, short of taking the intake off again to see if anything looks off I don't know what else to try.
I have read some past posts about these two DTCs and could not conclude anything, one post did say they replaced the Purge valve with the Hyundai part but I did that repair last month for EVAP codes.

THE FIX:
turns out that I did not smoke test the intake properly.... I was using the brake booster vacuum port on the intake to hook up my smoke tester. What I should have done is use the intake tube. When did smoke test it properly, I found out my issue was a bad quick connect fitting for the brake booster. Ordered a new one (Part number: LZN100220L). Make sure to used Brandon318's DIY to easily replace this fitting. DIY LINK

 

I know it's a pain to do, but try swapping the upstream O2s to see if the fault codes move to Bank 1. Or, if you still have the old O2s try replacing the new Bank 2 O2 sensor with one of the old ones. Bosch O2 sensors have some history of being bad out of the box. That happened to me a couple times.

 

I still have the old O2s and I may try that after I lift the intake to inspect.
The only thing holding me back from changing the O2s first is the P0174 DTC, the system is detecting a lean mixture, my thinking now is there has to be some sort of leak that I can't see with the smoke.