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I just bought this car, it seems to all be stock accept CAI, and it has donor LT1. It seems to be running rich in WOT. I was told there was a EGR valve bypass done. Not sure if that affects BLM. Regardless, these are the readings I was getting from freescan9495. My BLM was at a consistent 128 regardless of rpms. My question is there anything here in the photos below that would point to a rich condition? Also I heard about L99 and was wondering if you could tell the difference from pcm number?. I haven’t had the chance to get under her yet.. 😉 any useful information about this mystery engine would be appreciated. She roars I’ll say that much. Can’t wait to start my journey to a nitrous system and eventually a turbo. Obviously I need headers, pistons, etc.🙄
It looks like you are not in closed loop, so BLMs don't yet mean anything. Also, your Bank 1 (left) O2 may have an issue (if it is not rapidly changing in reading, which you can't tell from a snapshot). Noticing that the left O2 says not ready, but right does. Injuneer has more insight into this kind of stuff than I do. I don't play with it much anymore.
It's most likely still in open loop because Bank 1 O2 sensor is not ready. May be stuck too close to 450 mV reference voltage. Has to move higher to indicate it's working and pass the diagnostic. Engine run time and coolant temp is high enough to enable closed loop, but the O2 sensor voltage has not moved enough. In open loop the O2 sensor volts and short term fuel trims (INT) will not fluctuate like they do in closed loop. They will start to cycle up and down, short terms will start to jump around, when system enters closed loop. Long terms will only change when learning is enabled, which requires closed loop. The “1” in the “Reset…. this run” indicates PCM has been reset (cleared), hence the 128 long term fuel trims (BLM)
The knock retard may be the result of a knock sensor fault. MALFUNCTION 43C appears to be indicating an open circuit for the KS. in all the hundreds of Scan9495 I've looked at it’s the first time I've seen that show up. If knock sensor is faulty PCM will retard timing almost all the time. Car will feel sluggish.
What you really need is a data log from Scan9495 in .csv format. Upload in a post and I will look at it. See my guideline on running a log - See post #2:
Since it’s not going into closed loop, let it idle for 4 or 5 minutes to warm up, then drive it for 5 to 8 minutes. That should provide enough data.
An L99 265ci block will have casting #10168588 and have “4.3” cast in the side of the block. LT1 block has “327” cast in several places, which is last 3 digits of block part #.
Replaced knock sensor, o2 sensor and spark plugs. here is the data log you asked for, seems to be bogging under 3500 rpms WOT. i have a gasket kit on the way for this stock motor, got some leaks. really would like to be capable of some burn out.
I'll take a look at the log. Right now I’m a bit backed up due to recovering from eye surgery, and another eye surgery in two weeks. Couple others in front of you.
Preliminary review (why did the log include two copies of the same file?) indicates the BLM's (long term fuel trims, LTFT) are pulling fuel out under idle, low and moderate load). Yet at WOT, they are adding fuel.
Have you checked the fuel pressure? Check at idle with vacuum line on and off the fuel pressure regulator. Tape the gauge to the windshield and measure pressure under heavy load - WOT, at least 5,000 RPM. Almost looks like the fuel pressure regulator may not have a functional vacuum line. Just a preliminary guess.
07-18-2021, 07:15 PM
