I have an intermittent "hard stumble" in my '94 Chevy 350 pickup. It occurs when the truck is in the 1,700-ish rpm range and MAP is at 75 KPA-ish. It's a quick event; the motor takes a hard stumble and then recovers. It doesn't happen all the time at that rpm/map range; just sometimes.
I can see the event in my TunerPro log files, but don't know what's causing it. Here is a table that shows the event, plus a few before/after consecutive events. I've highlighted the event in bold italic and used red font for categories where obvious differences occurred, some of which may not be relevant.
TunerPro Sample # Battery
VoltageBlock
Learn AddBlock
Learn CellBLM Fuel Pump Voltage Fuel Usage IAC Desired IAC Preset Motor Position Inj DC% Inj BPW MAP Spark Advance ECU Loop Ref Period Tach RPM Knock Counts 6765 13.4 FALSE 10 125 13.7 14.7 68 68 10.48 3.75 74.2 29.9 1666.17 1675 303 6766 13.5 FALSE 10 124 13.7 14.9 68 68 10.35 3.71 73.8 29.9 1666.17 1675 303 6767 13.5 FALSE 10 124 13.7 15.1 68 68 10.27 3.68 74.2 29.5 1666.17 1675 303 6768 13.4 FALSE 11 124 13.8 3.9 68 68 40.38 3.85 74.2 19.7 6301.54 6300 303 6769 13.4 TRUE 10 124 13.8 14.4 105 77 10.73 3.85 74.6 23.9 1683.29 1675 303 6770 13.4 FALSE 10 124 13.8 14.6 105 91 10.73 3.85 76.0 26.0 1666.17 1675 303 6771 13.4 FALSE 10 124 13.7 14.5 105 105 10.82 3.88 76.4 27.1 1666.17 1675 303
The knock counts start at 303 and don't change the entire log and there's no knock retard recorded.
I'm running a BHMX 16196395 $0D chip that I've modified to improve the VE and Spark curves. The truck has a mild cam, Summit aluminum heads, shorty headers, stock TBI & manifold, all CA emission approved.
Greatly appreciate any thoughts!
Bookmarks