I’m having this same issue with no boost leaks, new coils, plugs, index12 inj. With less than 4k miles. It drives me nuts. It’s the only issue with my car but it’s bad enough to frustrate me every time I drive it.
I’ve logged many times trying to see what’s fluctuating to cause the push- pull feeling the car makes at very light load. My trims go bonkers, a fairly consistent pattern where they vary every half second or so between -10 to +25 and afr bounces in similar fashion as a result. My throttle value stays pretty consistent during the event, as does throttle position. A throttle adapt reset will completely eliminate the issue for all of about 15 minutes after resetting.
I had this surging issue for the longest time. I had a tuning accident and broke my intake manifold and throttle body at the same time. I replaced both and did the manual throttle reset. I'm not sure if it was the new to me TB or the reset that did it, but i haven't had the issue since. In my case it was prevalent with jb4 and flash only so it's not JB4 related.
1. Insert key, foot off the brake, foot off the gas.
2. press start button.
3. Press on gas pedal all the way down for 30 seconds.
4. While foot on pedal at 30 second mark press start button, release gas.
5. Leave key in, wait a full 2 min to start, press brake hit start button and drive.
Man, this sounds more and more common for our cars as they are getting older. I wonder if it’s possibly been a problem with some cars for years and I’m just now paying attention, or if it’s showing up more and more on the platform.
I have tried about everything I can think of, short of replacing the TB, and entire motor with it haha. If anyone finds a possible culprit, please share with us! The thing that is consistent about the issue is, on every log, trims and afr go crazy with up & down spikes. The OP claims his issue is very similar, and he has tried many different angles to attack the problem as well. It has to be something simple, but what?? Mine will even do it in 6th on the highway with very light throttle input. Accelerating very slowly in first will cause the car to buck and make me feel like my first day driving stick .
It seems, at least for me, that this issue always arises during spring time. Any chance this could be something to do with temp and fuel changes? I noticed lately that my issues has been less and less pronounced and I have not reset any adaptations thus so far this year. Last year I just reset adaptation with my BT tool and it seem to make the issue go away.
I've seen multiple people say it's not JB4, but seems most prevalent on JB4 cars to me. Only time I've ever experienced it was when JB4 was in for a couple of months in 2016. Had to mess with 10, 11, 12, FF, PID, etc. and torque request to get rid of it. I've never had surging flash only before or since.
To discount JB4 as a source, it needs to be completely removed from the car. Any time it's connected, it controls boost.