Here is a bit I posted when I got ahold of a scan tool a while back...
OK this one is probably for BigMike...
Put a fuel filter on and no change.
Then I got a hold of a decent scan tool so I could see stuff in live time. OBD 2 is kinda cool. Most everything seemed to fluctuate properly but a couple of things seemed odd to me.
The first thing was that if I had any more than about 32% on my TPS the timing would retard itself drastically. At 25-32% TPS while I was getting on it I had maybe 30-38° of timing advance, then above 32% TPS the timing advance would drop off instantly to like 15-20° advance which is when it "falls flat" and I can't get any more RPM.
Just for kicks I actually taped a screwdriver to the throttle pedal to keep the TPS under 32% and then I could finally get redline! I could almost leave it like that but I am positive there is more power to be had if I could open my throttle all the way.
The only other thing was that it switched from closed loop to open loop at different times when I was fluctuating the load and throttle. Maybe that's not odd, I don't know.
So based on the timing dropping off after 32% TPS should I suspect a bad crank sensor, coils, bad ECM, or what?
Oh and what should long term fuel trim and short term fuel trim look like?
