I've owned my my LGT for only 3500 miles, and it used to run pretty well. Old datalogs showed 1.0 DAM and no feedback knock or fine knock learning. However, lately the car has not been running well. And by lately, I mean after I took the turbo off and on many times and changed out the AOS system.
'08 LGT, 89k miles
VF52 w/ 200 miles on last rebuild.
Turbosmart Kompact BPV
Zeitronix Wideband O2 logging system and multi-gauge (w/ MAP sensor)
Protuned about 30k miles ago (2012) in Georgia (car is now in NY)
The car seemed to run fine before I ran into turbo problems. The last turbo had a slow oil leak, so I had it rebuilt by JmP. Shortly after I installed a newly rebuilt turbo, cold NY weather and the Crawford AOS created a big problem. Condensation in the AOS lines caused the crankcase vent to freeze, and the excess crankcase pressure caused oil to go back up the turbo drain. This resulted in the newly rebuilt turbo blowing a TON of oil into the intake, downpipe, and upipe. It was a mess. I found ice and water in all the hoses for the AOS.
So I had the turbo rebuilt again! I installed it back into the car and replaced the AOS with the stock PCV system. This is much better for a daily driver in cold weather. Shortly after that install (or immediately after? Not sure), the car has had some issues.
1) When I shift quickly with even small amounts of throttle applied, the car sometimes bogs down for 1-2 seconds after I shift in any gear. It's as if the injectors shut off completely when they shouldn't. I did notice that the AFR will drop low (10.5) for a second after I let off the throttle and shift, but I thought that was normal due to the throttle slamming shut.
2) When cruising at low load, it sometimes feels like the car is not getting steady power. It feels like the ignition timing might be changing. It's a subtle feeling, but it just doesn't feel as smooth as it should when I'm cruising.
3) See attached Cobb AP datalogs. Datalog3 is when I acceletered in 2nd gear and shifted to 3rd with some throttle on. I got 1 knock, and very uneven acceleration. Datalog4 I was cruising in 3rd and had a couple partial throttle runs hitting 18psi. I didn't WOT because my boost hits 20-21psi in the cold air (20F).
Any ideas? And what I can do to improve the data logs to debug this?
Thanks in advance!
Last edited by Dispatch20; Yesterday at 11:35 AM..