Thought I had this figured out but alas, something else took a shit on me yesterday. Thursday the car ran fine after I moved the PCV line, but Friday on the way to the dyno it started knocking and leaning out again. This time, REALLY leaning out. As in idling at 19.9 AFR! Loud ass metallic sound coming from what appears to be the exhaust side of the motor.

Towed the car back home and tore it apart today. Adjusted a few of the exhaust valves on cyl 2&3 that were super duper tight. Put everything back together and ran a cold compression test. Results were normal. Started her up, she idle'd at 15.0 AFR for 10 seconds then nosedived to 19.9 in a matter of seconds. Metallic sound came back so I shutoff the car. Closed loop is off.

And so she sits. Gonna tow it to a shop next week,but for now I'm out of ideas of what to check. Have at it...

 

This sucks...
Where's Mase? Have you given him a call to pick his brain on this yet?

 

Look at what is happening on the air temp size as seen by the AEM, you may find that the air temp sensor calibration is out.

Also, its worth putting a fuel pressure sensor into the fuel rail and logging it to make sure you dont have a problem with your fuel delivery.

 

Using Kpro not AEM

 

yes there is air temperature comp. tables in kpro that should been adjusted after your tune but I have a feeling things were not done right

 

My air temp comp tables are fine.

 

Look at the injector cycle time at idle as its leaning out. If the injector time is changing ( reducing) at the same rate as your leaning out then the ECU is being mislead by some input, or its programming is wrong.

If the injector time is staying constant, and your fuel is leaning out, then it will be something out of the ECU's control.

Another thing to check is your air/fuel meter heater circuit. If its not operating the heater correctly the O2 sensor will be cooling down at idle. When they get cold there is an offset error in the reading.

 

Injector time is constant and normal. I know its a mechanical issue, just not sure what. Vacuum line are good which leaves the fuel pump. The odd thing is the car still runs @ 19.9, albeit it sounds like metallic shit

 

Can you get a high resolution pressure transducer on the fuel rail to monitor the pressure.

Also, can you fit another known good air/fuel meter independent from your current air/fuel meter.

 

yeah, the datalog looks right, I would check your fuel pressure