Detect worn timing chain by oscilloscope

He, you're absolutely right to pay close attention to crankshaft/camshaft correlation, especially on engines with timing chains like your Renault Mégane III with the H5F400 (1.2 TCe). These engines are known to suffer from timing chain elongation, and your use of an oscilloscope to compare signals is spot-on and very much in the spirit of what Dan from diagnosedan.com demonstrates.

Background on the DD-5955 signal pattern

In Dan's video/article (specifically DD-5955), he shows how a worn timing chain alters the relationship between the crankshaft and camshaft signals. The key metric is how many crankshaft teeth (or pulses) occur between a fixed reference point on the camshaft signal and the gap in the crankshaft signal (which, as you correctly observed, is the 2-missing-tooth position).

On a healthy, fresh chain, the number of crankshaft teeth (each 6° as you calculated) between the rising or falling edge of the camshaft reference signal and the missing-tooth gap should be fewer than with a stretched chain. That’s because a worn chain causes the camshaft to lag slightly, so the cam signal shifts relative to the crank signal.

What we know about the H5F400:

• Crankshaft: 60-2 teeth = 58 physical teeth, each tooth = 6° crank rotation
• Chain elongation = camshaft lags, increasing the number of crank teeth between the signals
• From various cases and scope captures, a healthy chain typically shows 5 or 6 crank pulses between the gap and the camshaft signal.
• When you see 7 pulses as in your capture — and as in Dan's worn-chain example — it suggests wear and likely stretch.

Direct answer to your question:

Zitat

"If 7 crankshaft pulses like in my picture already defines a worn out chain, how many pulses will I count for a freshly mounted timing chain?"

Answer: On a fresh timing chain for the H5F400 engine, you should expect to see 5 or at most 6 crankshaft pulses (i.e., 30°–36°) between the missing-tooth gap and the camshaft reference edge (usually the rising or falling edge of the inlet cam signal).

Seeing 7 pulses (42°) suggests the camshaft is lagging behind due to chain elongation — a typical early sign of chain wear.

What to do now?

• If you're seeing 7 pulses just like in Dan’s case: you're very likely in the "warning" zone — the chain is not yet broken, but it is stretched enough to affect timing accuracy and possibly emissions or performance.
• Consider a timing chain replacement soon, especially if you have:
  • Cold-start rattling (even briefly)
  • Fault codes like P0016 / P0017 (crank/cam correlation)
  • Slight power loss or increased fuel consumption

• Make sure the tensioner is functioning — sometimes weak oil pressure or sludge affects timing even before chain wear becomes severe.

  Greets Micha