[Gmecm] Engine is not smooth at steady cruise
dermot.ohare at chemistry.oxford.ac.uk
Thu Oct 20 10:31:00 CDT 2005
I have heavily modified 4-cylinder Lotus Esprit Turbo, runs on a GM
1228708 using a speed density system.
In 5th gear, trying to hold steady 85 mph, 3500 rpm, MAP about
100-130 kPa, ECU is in closed loop. O2 cycling between 0-0.65 V.
The engine is lumpy, like a slight hesitation. It feels like a very
slight misfire, press the throttle and it goes away as it richen up
the mixture and accelerates under power perfectly.
Could it be a lean cruise condition, the other suggestion I have
been told is that the ECU may be reacting too quickly to the O2
swings? When the ECU is reset it is not so bad but gets worse as
the ECU learns the fuel trim, BLM values are way down.
If a change the VE table will the BLM values not bring it back down
anyway, in closed loop the ECU is not running on them.
What am I missing here....
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