Hello
Here I have a Chevrolet Spark 2010 1.0l 16v. Starts and runs but lacks power with a slight misfire (incomplete combustion) at idle. Suspected valve timing. Timing marks are coloured chain links and only one mark on the crank gear. Old chain had stretched by one link. New chain fitted. Waveform captured is with inlet choked. Without choke vacuum pocket on exhaust stroke was -2.5bar! What are your thought?