10/06/2026
This is why I love the cylinder leak down test...BUT ... paired with a video scope....
Classic issue for most people at some point. : client comes in..Car running rough under load....misfire codes stored in PCM
Vehicle :
Has new plugs new ignition coil done elsewhere.
Misfire cylinder 3 never changes , check injectors make sure no fault there and..
Move on to A leak down test right away, now 10% is considered "normal " ...and we only have about 5% ...
but when you listen to where that 5% on this engine is going .. you hear it clearly when you pull off the oil cap...
Which means pressure is pushing past the rings into the oil pan and when we open the cap you can head the air rush out...
No problem...throw a video scope in and take a look for any damage ..and there it is... Excessive oil getting by the rings at idle and just off idle..... and under load would be considerably more .
No fix for this, vehicle needs and engine and we avoid hours and hours of aimlessly testing components had we just accepted the 5% was ok as a standard.
" Standards " are not always standard...
Great diag by Apo, answers to our problem and repair plan layed out to our client...not always good news...but the correct news not just new parts to " see if it works "