05-19-2014, 05:42 PM
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#781 (permalink)
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A True Z Fanatic
Join Date: Mar 2009
Location: Houston, TX
Posts: 4,024
Drives: too slow
Rep Power: 3594
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Made a video from datalogger recordings on the flywheel thing. Youtube desc copied for embed:
Quote:
Audio comparison of "normal" and "something's wrong" engine sounds from Saturday. That "something's wrong" sound slowly builds up in the data all through the second half of Saturday. I couldn't hear the difference from the cockpit with a helmet on so I had no idea about this Saturday, but the datalogger mic is up under the dash close to the firewall and you can really hear it in the video.
The 3rd clip is when things actually went crazy Sunday morning and the car died for the day. The ECU went into some kind of limp mode and started aggressively limiting revs and speeds to try to prevent damage, and may have retarded timing and whatnot as well. The RPM gauge is really nuts when it happens. I ended up killing the engine off on the side of the track and getting a tow, as I couldn't maintain more than ~10 mph and the engine was threatening to die on me constantly, and I wasn't sure if more damage was being done.
ECU had code P0335 (Crankshaft Position Sensor). That sensor reads the flywheel. During a couple short restarts in the paddock, there were some clanky sounds that could be coming from the bellhousing area, but otherwise the engine seemed to run ok at idle and low revs. Pulled the (magnetic) sensor and it had scratches and grooves on the tip of it like the flywheel (or something else) had hit it, or at least rubbed into it pretty good.
Most likely I've got a cracked/damaged flywheel and/or a loose bolt in that area, plus a damaged crankshaft sensor. The parts are pretty cheap (~$300 combined), but it means dropping the trans to diagnose and fix.
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