14 AFR under 16 PSi out of nowhere

[classicauto]

Last night while I was leaning out my AFR's in the vacuum cells. I noticed that when I do a full 16 PSi pull now, my AFR's go to 14!!! That is dangerously lean and I only let it run for like a second. Thinking that I may have edited the wrong cells by accident, today I loaded up the laptop and loaded the original map that was tuned before. Unfortunately its still doing the same thing...

Also, a bit after this test my air intake temps went to -25C and stayed that while for 10-15 minutes which made my vacuum AFR's rich and my 16 PSi loads roughly normal (~11 AFR). After about 10-15 minutes, it jumped back to normal (55C) and the 14 AFR problem under boost came back.

Ok, so theres a few things that I think this can possibly be. My air intake sensor obviosly needs to be replaced or wiring fixed. Now there is a possibility that the wideband sensor (Bosch) is almost dead and giving bad readings, however it can read rich AFR's still. I'm thinking since it only does it under boost and WOT, that it could be the fuel pump or fuel filter. Although when the air intake sensor died, I had proper AFR's so it might not be the pump so I'm leaning towards the filter. Also, could the TPS be a possibility? It might not be reading my full WOT position and therefore not putting enough fuel. It can also be the injectors but I'm hoping it isn't.

Has anyone ever had something similar or have other possibilities? I regularly track the track (almost every week) so I'm pushing it to the limits for prolonged periods often. Also the fact that I run 16 PSi at the track also pushes it even more.

thewird

[thewird]

Last night while I was leaning out my AFR's in the vacuum cells. I noticed that when I do a full 16 PSi pull now, my AFR's go to 14!!! That is dangerously lean and I only let it run for like a second. Thinking that I may have edited the wrong cells by accident, today I loaded up the laptop and loaded the original map that was tuned before. Unfortunately its still doing the same thing...

Also, a bit after this test my air intake temps went to -25C and stayed that while for 10-15 minutes which made my vacuum AFR's rich and my 16 PSi loads roughly normal (~11 AFR). After about 10-15 minutes, it jumped back to normal (55C) and the 14 AFR problem under boost came back.

Ok, so theres a few things that I think this can possibly be. My air intake sensor obviosly needs to be replaced or wiring fixed. Now there is a possibility that the wideband sensor (Bosch) is almost dead and giving bad readings, however it can read rich AFR's still. I'm thinking since it only does it under boost and WOT, that it could be the fuel pump or fuel filter. Although when the air intake sensor died, I had proper AFR's so it might not be the pump so I'm leaning towards the filter. Also, could the TPS be a possibility? It might not be reading my full WOT position and therefore not putting enough fuel. It can also be the injectors but I'm hoping it isn't.

Has anyone ever had something similar or have other possibilities? I regularly track the track (almost every week) so I'm pushing it to the limits for prolonged periods often. Also the fact that I run 16 PSi at the track also pushes it even more.

thewird