Having an issue with 383 TBI and new to data logging
Hey all! This is my first post. Hoping to get some understanding of the data I logged from my truck tonight. Here some specs from the truck:
1990 Chevrolet K2500, 383 crate engine (originally a 350), 1228747 ECM/Stock TBI system with new chip that came with the engine, SM465 Manual Transmission
It has ran okay since the engine was put in last August, but I think it can be even better. There was a surging idle when cold that I wanted to get rid of and try to get the most out of the new engine. I pulled, cleaned, and rebuilt the TB, replaced the TPS, IAC, MAP Sensor, O2 sensor, ICM, and ignition coil with stock L05 replacement parts. When I did the TB rebuild, I also put in a new 18 PSI FPR spring to allow more fuel to feed the extra displacement. After getting it all back together, it isn't running very well at all. I have adjusted the TPS to show the correct voltage when the throttle is closed, reset the IAC valve, and adjusted the idle screw to where it now will idle pretty well when cold. After things warm up and it runs in closed loop, the idle gets progressively more rough and will eventually stall. Also, the tach needle will begin to jump around when the actual engine RPM doesn't fluctuate much at all. After that its nearly impossible to get it to run again until it cools back down.
Today I recorded some data from startup to stall to see if it shows what is going on. Here is a link to the data in an excel file (https://drive.google.com/open?id=0B-...WW8&authuser=0). From just a little research into what the parameters are, I see the BLM value steadily increasing from the time closed loop starts until the engine quits. An increasing BLM means that the O2 sensor is reading lean and the ECM is trying to add fuel to bring the O2 sensor reading down? Also I see that the High Battery Voltage result starts OK, then goes to ERROR. I didn't see any codes being set during the entire run either. Is my understanding of the BLM value correct or do I have it backwards? My theory is that the new FPR spring is exposing the fuel pump as being too weak to supply the engine with the fuel it needs. I have a new higher output pump, new fuel filter, and reconditioned injectors ready to go in this weekend to fix it. Is there anything else the data is saying that i'm missing?
