|Vehicle details:||Skoda Octavia|
|Author:||George Cameron | Ibrox Vehicle Repairs & Diagnostics Ltd.|
This vehicle was recovered from another garage after having its engine rebuilt. It would start and then cut out.
There was a fault code of “engine speed sensor implausible signal”. We checked the output of the crankshaft position (CKP) sensor and found an irregularity in the waveform:
We zoomed in to get more detail:
The crankshaft waveform (lower trace, blue) shows an obvious fault 7 to 8 teeth after TDC. Removing the crankshaft sensor and looking with a borescope, I could see that the reluctor ring had two slightly bent teeth.
I removed the sump and realigned the two bent teeth, and all was well.
Total time for diagnosis and repair: 1.5 hours
Download the PicoScope data files of the waveforms featured in this article:
July 03 2010
Good posting George.
A fairly straightforward fault,but a credit to you for a well structured approach to the problem.
The more I read these postings dipicts how good Pico and the techs are, convincing me more so to sell the old fluke 196 and move up to Pico.
July 03 2010
Hi, Had exactly the same problem on an XC90 only without a scope it three days to find! At least it got me my new Picoscope!!!