Owned my 04 GTP for 2 years now and I think I may have finally figured out why my LTFT's have been very rich (-16 to -25/maxed).
If I disconnect and block the PCV hose that goes from behind the MAF to the top of the SC, my idle trims immediately become perfect. (I've still been making sure the PCV has air)
I'm aware that this hose pulls air into the PCV system post-MAF, which will be "robbing" a little bit of air from the calculated A/F, but I feel that this hose causing this level of rich LTFT is a sign that something isn't right.
- There doesn't seem to be any noticeable pressure/vacuum from the oil fill hole, and the engine doesn't behave any different when it has been removed while running.
- PCV valve is only about a year old
- LIM gaskets are changed
- 100k miles, stock pulley, vacuum is good
- Swapping MAF made no difference
- Doesnt consume oil
What do you guys think of this? Hopefully I'm not sounding too confusing.
