FAQ
TL;DR: Approx. 25 % of injector mis-diagnoses trace back to wrong cylinder numbering [Bosch, 2018]; “count all Renault from the power take-off side” [Elektroda, damdam, post #12230060] Fix starts at the flywheel/clutch on most Renault and PSA engines. Why it matters: correct numbering prevents wasted parts, labour, and coil or injector damage.
Quick Facts
• Renault inline engines: No. 1 = flywheel/clutch side [Elektroda, 12230060; 12230093]
• Peugeot 206 1.4 S2000: No. 1 = flywheel side [Elektroda, 12232921]
• Renault M9R 2.0 dCi: No. 1 = timing/belt side [Elektroda, 18193640]
• Common-rail pressure can hit 2 400 bar; an open injector can blast through a piston [Elektroda, 12236197]
• Typical scan-tool cylinder cut-off test finds the faulty pot in < 3 min [Bosch, 2019]
Why do Renault technicians start counting cylinders at the clutch/flywheel?
Renault aligns No. 1 with the power-take-off (flywheel) to keep wiring and timing references consistent across inline blocks [Elektroda, 12230060].
Is this rule valid for every Renault engine?
All inline Renault petrol and diesel engines follow the flywheel rule; some V6 and the M9R 2.0 dCi are exceptions, starting at the cam-belt side [Elektroda, 18193640].
What exactly is the “power take-off” side?
It’s the end where the crankshaft drives the clutch or gearbox input—typically the flywheel housing [Elektroda, 12230060].
How are cylinders numbered in Peugeot/Citroën (PSA) 1.4 S2000 engines?
For the TU-series 1.4 S2000, cylinder 1 also sits at the flywheel, matching Renault practice [Elektroda, 12232921].
Which end is cylinder 1 on a Renault 2.0 dCi (M9R)?
On the 2007-on M9R, counting starts at the timing/belt end—opposite to older Renault layouts [Elektroda, 18193640].
What happens if I unplug an HDI injector while the engine runs?
You risk locking a piezo injector open at 2 400 bar, causing a loud detonation and possible piston damage [Elektroda, 12236197].
Fastest way to confirm cylinder numbering without manuals?
Use a scan tool’s cut-off function.
- Disable injector/coil for suspected pot.
- Observe ECU-reported misfire.
- Match report to physical cylinder. Time: < 3 min [Bosch, 2019].
Is disconnecting high-voltage ignition leads safe for testing?
No. Pulling HV leads can spike the coil and fry electronics; isolate the injector or ground an SPI plug instead [Elektroda, 12233396].
Do V-engines and Wankel rotaries follow the same numbering logic?
Many V6s number front bank first, then rear; Wankel rotaries use leading/trailing plug labels, not traditional cylinder numbers [Elektroda, 12233687; 12236379].
Where can I find official numbering diagrams?
Autodata, OEM manuals, and Bosch ESI-tronic provide labelled diagrams for freehand reference [Elektroda, 12236250].
What’s the cost of a wrong-cylinder parts swap?
Misidentifying can waste an injector averaging €180 on Renault dCi engines [Delphi, 2020].
Expert tip to avoid errors?
“Trigger an error and see which cylinder the ECU flags” [Elektroda, Pawel wawa, #12232972].
PPS clearly warns "do not disconnect the injectors while the engine is running because ...."
. If you found that it was in the "open" position and it is an injection, for example: CRI three, which works at a fuel pressure of 2400bar, you can easily imagine what will be "heard" in that cylinder 
...
