I have a 1999 Civic Si Throwing a CEL.

Car was boosted before, and Now back to stock.

But its a LS/VTEC now.

B18A1 Bottom end with Crower Rods, and CP 9:1 Compression.
B16a2 Original head, With dual valve springs and retainers.
Header, Hi-flow cat, and Magnaflow B pipe with Twinloop Axleback
Walboro 255lph still in the car. Stock P2T 99-00 Si ECU.
Stock intake box with MAF Sensor stuck in.


Its throwing a CODE P0170

Fuel System too Lean Bank 1.

I have a Brand new Distributor (so new cap new rotor buttom)
New Spark plugs and Wires.

I just did a Valve Adjustment today, Water pump and Timing belt.

How could I check to see if theres a Vaccume leak?

How could i check if the MAF Sensor that goes to the Intake is Faulty?

And is there a Way to Check if the O2 sensor is still good?

Please let me know. Im tired of driving on Tag Applied for Tag.