Have had my truck running with the same tune for about a year now (daily driver, about 35k mi) with no issues. Recently started shuddering occasionally while the truck is moving (most noticable while at cruising speed) which occasionally throws a CEL with a P0101 MAF performance code. Nothing on the truck has changed, just started getting this code and noticing the shudder. Only once recently have I gotten a P2135 TPS code... my thoughts below.
- Truck is an 03 Tahoe with a 6.0L LQ9 swap with long tubes (so no cats) and an AEM WB O2 (plumbed into/logged by the tuner), and tuned by a performance shop in my area (Dallas, TX).
- MAF swap (new sensor install) didnt clean up the MAF data in my logs, but also doesn't seem to be the culprit as the MAF seems stable thru the blip. Throttle position sensor also looks pretty stable.
- Fuel system seems out of the question to me, as the inj duty and eq ratio seems good. Doesn't seem like it's low on fuel for any reason.
- The computer is obviously reacting to something, given that the eq ratio goes rich immediately after the shudder/timing blip. Can I better instrument/log this somehow?
- I have my most recent log attached, showing one of the more noticeable blips I am talking about at timestamp 5m38s.
Having listed the my symptoms/thoughts, this just reeks of "sensor issue" to me, given that the truck has been running fine for months prior to this step change. I'm just trying to figure out whether the problem is staring right at me in the data I have so far. Any advice or ideas for additional logging would be appreciated!
P.S. Have seen only one other post addressing something similar to this in the Gen 4 forum where they were talking about MAF flutter... New here to the forum and tuning, so please forgive if this is something that's already been covered elsewhere and I just can't figure out how to find the results I need. Trying to use this problem as a way to learn more about tuning/logging.