C2C7360

 

Okay stop and let's start with some much more surefire and simple checks before you throw more parts and time at this.

First off a vacuum leak is extremely easy to find, just have the engine running and spray brake clean at each suspected leak point. If there is a leak point the engine will stumble once you spray that area. You don't need to waste time or hassle with smoke machines or pulling each hose/line off and blocking it and rechecking. The only thing that is hard to check this way is an EVAP system leak but that's a separate system we don't care about right now.

For the O2 sensors your car uses denso sensors and a majority of the other electronic parts like coils and alt are also made by them. However before you go just throwing parts at the problem you can easily check the sensors, both bank one (firewall side) and bank 2 (radiator side) have both sensors on long leads that click into their connectors that are easy to get to. Two for the rear bank are near the EVAP purge solenoid and the front two are just under the battery tray. Check them both for continuity and resistance, then backprobe them while the car is running to check voltage (aka signal) if you don't have a scanner that can tell you in real time what the ECU is seeing. If the signal seems strange or doesn't "switch" back and forth in a predictable range once in closed loop or appears pegged out then change it.

If you have a lean code but no running issues it's unlikely to be an upstream O2, downstream O2s are irrelevant to engine running conditions.

 

Thx Striker. Can you tell me more on how to test the o2 sensors please. Thx

 

Unplug the connector from the car side harness and use a multi meter to inspect them, you would need to look up the specs for your sensors. I am not at my shop right now otherwise I would look it up for you