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Car jerks on low rpm cruising impossible

Practical Reflash Tuning

Relevant Module: The 6 Step Process > Step 6: Confirm Calibration on the Road

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Hi, my car jerks between 1200/2000rpm. I have a ls1 stroker 383 big cam shaft. Once i open the throttle it won't jerk. Only jetks if im trying to stay on one speed to cruise, throttle not opened as much. How can i fix this issue, or can't it be fixed because of the large cam.

Depends on the ECU. Often this is a setting that is allowing idle control to take over, or Deceleration Fuel Cutoff (DFCO) to activate when not desired. I've also seen this with a bad/worn throttle position sensor.

Or your tune could have some steps in either the fuel or ignition timing about that operating condition -- if that's the problem, try smoothing out the steps.

Bit late to the party but you can try retarding the timing and running it richer just to smooth it out. Just to start, try running a flat 20deg timing from 0 up to 0.32g/s load, and from 0rpm up to 2000rpm to see if that smooths it out (so the whole top left corner of your ignition map is all set to 20 deg). Then, again, as a test, set your power enrich throttle to 0 up to 2000rpm just to force open loop and add a little fuel. If you can make it happy with these two, just start slowly creeping those two settings back to leaner/more timing until it starts to misbehave again. Also make sure your timing in your log is sitting flat at 20 and not bouncing around from any other corrections.

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