Hello guys, I have a problem of analyzing Px. My car is unstable at idle. I suppose it can be a mechanical issue.
I checked the compression in all cylinders, and was found to be 11 kg/cm
Attached are cylinder pressure graphs.
-right side cylinder number 1
-left side cylinder number 5
I've just started to work with USB Autoscope. Any idea's where I should start looking at the problem?
MERCEDES W140 engine #119970
MERCEDES W140 engine #119970
- Attachments
-
Mersedes_W140_Px_left.mwf- (40.21 KiB) Downloaded 533 times
-
- Mersedes_W140_Px_right.mwf
- (39.85 KiB) Downloaded 534 times
-
knyshmotors
- Posts: 86
- Joined: Fri Mar 06, 2015 2:10 pm
- Location: Buenos Aires, Argentina
Re: MERCEDES W140 engine #119970
Very interesting motor, in 91 year, already has equipped with a CAN bus and a variable valve timing system.
In your waveforms observed too late opening of the left head exhaust valve , that probably caused by stretched chain that jumped on the exhaust camshaft gear.
Waveforms recorded at different engine speeds making difficult to compare them. both sides of engine have rather high cylinder filling, and insufficient vacuum in the intake manifold,
retarded ignition timing angle.
For a more detailed analysis the full files of waveforms recorded is needed for processing by script Px.
Repeat tests several times for greater certainty results. and put them in the forum or in the file sharing.
Good luck.
In your waveforms observed too late opening of the left head exhaust valve , that probably caused by stretched chain that jumped on the exhaust camshaft gear.
Waveforms recorded at different engine speeds making difficult to compare them. both sides of engine have rather high cylinder filling, and insufficient vacuum in the intake manifold,
retarded ignition timing angle.
For a more detailed analysis the full files of waveforms recorded is needed for processing by script Px.
Repeat tests several times for greater certainty results. and put them in the forum or in the file sharing.
- MBZ 140 119970 engine Px.png (155.42 KiB) Viewed 7142 times
Re: MERCEDES W140 engine #119970
I decided to replace the timing chain today and discovered that on the left side the chain jumped one tooth on the exhaust cam. Thank you for your help.