I have now a 2011 Chevrolet Aveo A12XER with misfires at cold engine ,only with the fault code P0300 and sometimes P0172.
Checking the signals from this engine (with vvt unplugged or not) I see a strange peak of pressure in cylinder at 360* after the TDC.
In Library I can't see a reference signal from crank vs cam.
Someone have o good reference to compare with my signals(I think this engine is used by Opel/Chevrolet/Cadillac/Buick/Holden).
- (2.25 MiB) Downloaded 505 times
I've had a look at your capture and although there isn't a reference on our waveform library for your specific engine, we can start to get an idea from your waveform as to what is going on here. With this increase in pressure just before the inlet valve opens we can assume the exhaust valve maybe closing early which is why we are seeing 1 BAR of pressure inside the cylinder before the inlet valve opens. There are a few similar engines on the waveform library under Vauxhall, and although they are not a 1.2 the engine code is similar. Looking at the compression tower and the crankshaft sensor they are both 14 teeth apart on both your engine and the one from the library. If we believe the fundamentals are the same then looking at your capture the cam timing is different between engines. I think I would start by trying to find a little history about the vehicle before going any further and trying to establish what happened prior to the fault occurring. I imagine there may be a some noise coming back through the intake manifold as well?
This is likely normal.victor2k wrote:I see a strange peak of pressure in cylinder at 360* after the TDC.
Here is an example of an HHR 2.4. May be similar to yours.
The VVT is not actuated in this part of the capture. When activated the bump vanishes. The bump is caused by the lack of valve overlap when the VVT is not active.
So... don't let that be a distraction.
Thank you for your support.
VVT engines isn't so easy to diagnose... ECU test his VVT/VANOS/VALVEMATIC system after the starting.
For the first time I see this on a MINI,now the same tests I can see on this engine...
Using GDS(other scanners :KTS,Launch -was useless on this engine) I can't find any fault codes(after the initial erasing of fault codes memory and 3 days of tests),until now I can't see a misfire in data list,the short +long fuel trim is aprox 1-3%
Here is a recording after the start of engine ,you can see how the VVT is actuated (or is a block of VVT?)
https://mega.nz/#!JVJ0kaxD!K_SEU7aTHC1I ... YoktrKAQ5o(I can't upload a file what exceed 30mb)
Today I made a new capture from ignition.On cyl 1 I have a strange burning line with noise(connecting order was 1-2-3-4).What can give this noise?
- (8.45 MiB) Downloaded 656 times
My measurement of relative compression didn't show any issues,but was made at a warm engine.
Today I tried something new.Measuring the pressure in cylinders with the same sensor+adapter and using the reference waveforms I could see some diferences at the beginning/closing moment of valves.
In my attached files was made only for cyl 1 and 2(the opening of exhaust valves) but can be compared any 2 cylinders
Can be used for an accurate measurement of valve timing without using 4 pressure sensors,only a few maths
Hello and thank you for your supportRYM6746 wrote:Although I have not seen the hashy burn line on the waveform (using my phone). I have seen that, with a blown headgasket and some of the symptoms that you describe also match. Coolant leaking into cylinder when left over night is a possibility?
I will inspect the engine for a coolant leaking.
The water in cyl1 can explain a increased compression at cold engine.A measured compression(1-2-3-4 is the order of measurement) at warm engine was attached.
Also I will make a new capture for CAM vs CRANK signals from a Corsa D /A12XER engine type this week.
I need some help...can be used dp/dt in the rail pressure for diagnose the injectors?
Image is attached...
- dp divided to dt for injectors.rar
- (895.6 KiB) Downloaded 439 times