Engine Shudder at low RPM under boost LS2 SD tuned
Attached is a log and a snapshot showing what I'm talking about. A friend's car was doing this, so I hooked my scanner up and logged for about 1 minute. He can't go WOT under boost because of it, in fact he can't increase throttle beyond maybe 50% without it shuddering.
Only happens when in boost/under load. Regular driving doesn't do it. Notice O2 B1 goes low when he does. I'm still learning, and this is more or less for learning for me. He's taking it back to the tuner this weekend. The tuner thinks it could be misfires but when I scanned, there are no misfires being reported. I didn't have a chance to look at his tune, only the log.
We checked all ignition wiring and plug wiring. He's going to check the sparkplugs this morning. From memory of looking at his tune a week ago, I don't recall misfire reporting being turned off.
Any help, suggestions or just pointing in the right direction would be sweet.
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