Knock Sensor readings - What is a normal ? V6 3.8L

[Charlescrown]

You can check your cam timing with a vacuum gauge. Around 20 inches @ idle provided you have a good engine with a std cam. You should also be able to read it from a log. I think it should be in the 30-40kpa @ idle but I may be wrong.

[vlad01]

cam timing as follows.


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Standard Valve Timing for the LateVS-VT-VX-VY EcoTech V6 Engine:

Advertised Valve Lift at height - 0.006 inches
Inlet Opens - 6.7 degrees BTDC
Inlet Closes - 57.0 degrees ABDC
Exhaust Opens - 65.3 degrees BBDC
Exhaust Closes - 15.1 degrees ATDC
Inlet Valve Duration - 243.7 degrees
Exhaust Valve Duration - 260.4 degrees
Inlet Valve Lift with 1.6 to 1 ratio rockers - 0.4099 inches
Exhaust Valve Lift with 1.6 to 1 ratio rockers - 0.4112 inches
Inlet Valve Lift at TDC - 0.0208 inches

0.050 Valve Timing
Inlet Opens - minus 24.4 degrees BTDC (24.4 degrees ATDC)
Inlet Closes - 25.8 degrees ABDC
Exhaust Opens - 31.6 degrees BBDC
Exhaust Closes - minus 18.7 degrees ATDC (18.7 degrees BTDC)
Inlet Valve Duration - 181.4 degrees
Exhaust Valve Duration - 192.9 degrees
Inlet Valve Lift with 1.6 to 1 ratio rockers - 0.4099 inches
Exhaust Valve Lift with 1.6 to 1 ratio rockers - 0.4112 inches
Ramp Rate - 2.22
Valve Overlap Seat to Seat - 21.8 degres
Valve Overlap at 0.050 inches - minus 43.1 degrees
Inlet Lobe Centreline - 115.2 degrees
Exhaust Lobe Centreline - 115.1 degrees
Lobe Separation Angle - 115.1 degrees

[immortality]

You can check your cam timing with a vacuum gauge. Around 20 inches @ idle provided you have a good engine with a std cam. You should also be able to read it from a log. I think it should be in the 30-40kpa @ idle but I may be wrong.

No MAP sensor on a VX commodore (or any ecotec equipped model) unfortunately.

[JohnDee68]

You can check your cam timing with a vacuum gauge. Around 20 inches @ idle provided you have a good engine with a std cam. You should also be able to read it from a log. I think it should be in the 30-40kpa @ idle but I may be wrong.

Thank Charlescrown,
The vacuum gauge seems to show no signs of timing or engine issues, which I am tending to think it could be either so small amount, or hopefully not an issue with the timing physically. I am still to finish off some further testing.

Attached is a pic of the vacuum gauge at idle from a cold start motor. though it doesn't vary much when at runnig temp either.
The past few days driving with the vacuum gauge in vehicle. From my memory of my use of a vacuum gauge in previous carby vehicles, I would have adjusted points, fuel or distributor timing to resolve what is a lower than desired vacuum on driving/acceleration. So i am leaning towards something a miss in the actual software "tune" of the PCM at this point.



Thanks, i will resolve this and let people know once that time happens.

[JohnDee68]

cam timing as follows.
Thanks Vlad01,
That info is invaluable. I am thinking that it can be possible with that info, to do a measurement of the timing without having to remove the timing chain cover now.
Thank you.

I found a picture of the timing chain taken a year ago while doing a water seal leak, i am pretty sure the chain isn't too bad. But i would be interested in others thoughts. unfortunately the pic doesn't allow to see the timing marks well, if at all.


--------------------------------------------------------------------------
Standard Valve Timing for the LateVS-VT-VX-VY EcoTech V6 Engine:

Advertised Valve Lift at height - 0.006 inches
Inlet Opens - 6.7 degrees BTDC
Inlet Closes - 57.0 degrees ABDC
Exhaust Opens - 65.3 degrees BBDC
Exhaust Closes - 15.1 degrees ATDC
Inlet Valve Duration - 243.7 degrees
Exhaust Valve Duration - 260.4 degrees
Inlet Valve Lift with 1.6 to 1 ratio rockers - 0.4099 inches
Exhaust Valve Lift with 1.6 to 1 ratio rockers - 0.4112 inches
Inlet Valve Lift at TDC - 0.0208 inches

0.050 Valve Timing
Inlet Opens - minus 24.4 degrees BTDC (24.4 degrees ATDC)
Inlet Closes - 25.8 degrees ABDC
Exhaust Opens - 31.6 degrees BBDC
Exhaust Closes - minus 18.7 degrees ATDC (18.7 degrees BTDC)
Inlet Valve Duration - 181.4 degrees
Exhaust Valve Duration - 192.9 degrees
Inlet Valve Lift with 1.6 to 1 ratio rockers - 0.4099 inches
Exhaust Valve Lift with 1.6 to 1 ratio rockers - 0.4112 inches
Ramp Rate - 2.22
Valve Overlap Seat to Seat - 21.8 degres
Valve Overlap at 0.050 inches - minus 43.1 degrees
Inlet Lobe Centreline - 115.2 degrees
Exhaust Lobe Centreline - 115.1 degrees
Lobe Separation Angle - 115.1 degrees

[vlad01]

Yeah it should give you a rough idea with the cam timing.

[JohnDee68]

August 2021 -
Well I managed to make up a exhaust back pressure gauge and tested the exhaust for restrictions.
The gauge only briefly moved from zero and as high as 2.5 psi for a fraction of a second at red line. So, thank fully I don't believe there is an exhaust issue. Another one ticked off the list of possibles.
I have also removed non factory external air drag and internal additional weight being carried.

Next on the process of elimination on the path to resolve my issue of poor fuel economy is;
- Actual valve timing without removing timing chain cover. a challenge, yes.
- Poor fuel. (E10) currently in use. Though previously with regular unleaded I would get even worse (nearly 200km) less per tank when not using E10.
- Poor or requiring tweaking of the "tune" for the motor.
- Transmission issues. Maybe just from a poor "tune".

John.

[vlad01]

If it's pulling timing all the time due to knock, false or real it's going to get poor economy.

[Charlescrown]

Look like lazy timing figures to me.

[Charlescrown]

That vacuum reading also says the rings and valves are in good condition. Provided it's not jumping around.