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

['quipt4it]

...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...

I just ran a straight edge along it lol. I would have tossed that...

Have you looked into all the usual suspects for poor fuel economy like spark plug gap and fuel pressure regulator. Does the exhaust smell richer than before. Are the spark plugs darker.
Is the air cleaner element in good shape (not dirty).
20 ins/hg is not bad vacuum, but I have seen higher on a stocker, there is barely any overlap.
We don't know how accurate that gauge is.
You can by-pass the knock sensor by running the PCM input to earth via a 4.7k Ohm resistor.

[JohnDee68]

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

That is where I am uncertain if there is any knocking in the actual engine. I am usually attuned to such things (in my earlier years), But I can honestly say I don't believe there is any knocking going on in the engine. Though, without a confirmation with a known device to test it, I cant be 100% certain either way.

Do you know if the professional GM diagnosis scanner can tell 100% if it is knocking at all? Not that I have one of those devices.

[JohnDee68]

...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...

I just ran a straight edge along it lol. I would have tossed that...

Have you looked into all the usual suspects for poor fuel economy like spark plug gap and fuel pressure regulator. Does the exhaust smell richer than before. Are the spark plugs darker.
Is the air cleaner element in good shape (not dirty).
20 ins/hg is not bad vacuum, but I have seen higher on a stocker, there is barely any overlap.
We don't know how accurate that gauge is.
You can by-pass the knock sensor by running the PCM input to earth via a 4.7k Ohm resistor.

Thanks quipt4it.
Fuel pressure was good at testing with minimal drop in pressure at rev increase. Yes the exhaust has smelt at times, mainly until it is to running temp, 89Degrees, but id say its more cat than rich issue.
Yeah i am not yet convinced that the slack on the left is an issue (mainly as cost to replace needs to be 100% justified first). I am still trying to measure cam timing without dismantling the rest required to just check it, Vlad01 has posted some useful specs which should assist in me doing that - Hopefully. But I also am inclined to feel it could be the issue or a contributor factor just I cant justify jumping in to replace it at the moment because of cost. I have thought, that lets say the chain stretched a full tooth. Then the chain was placed on the sprockets so that the timing marks were still correctly lined up. There would be justifiably slack on the left which in my logic (atm) shouldn't affect the timing as the drive side is still going to be correct under load. Though there also would be some issues with retarded valve timing on deceleration if that were the case. Am i correct in that logic? Wouldn't i see some other signs from the engine, like back fire if the cam timing was out by presumably 2-5degrees (maybe more) guessing by the slack in the chain?
I have good plugs, correct gaps, leads, coil packs, air filter (Wesfil Brand - so don't know the quality of its flow rate), all what I would say are working above average requirement and there isn't any misfire in the engine. The gauge could be of concern, though I had it on other vehicles with it showing results that I would expect (better) than what i get on my Vx currently.
Would having the knock sensors just disconnected, would it then not detect any knock and then rule out knocking or PCM retarding from knock detect? Or is there a requirement for the resistor to be inline as to give the PCM some value reading?
As this is a motor I refurbished, I am still not knowing its actual history very well. I do wonder why the exhaust valves were larger than the ones on the previous engine. Is it possible a Vy heads on this motor? Pic of valve size difference.

IMG20171212233637.jpg

['quipt4it]

The chain may not be contributing to your woes, however, if the slack is excessive it may lead to breakage.
It does also effect timing.
Just disconnecting the sensors will set a diagnostic code, and will run on a default timing figure.

['quipt4it]

That appears to be an exhaust valve, judging by it's bulky appearance. You have it sat atop an intake valve.
All eco's had the same valve sizes. Plus there is simply not enough in the valve spacing to fit that much of a larger piece.
Intake valves 45.8mm, exhaust 38mm.
Have you visually inspected the O2 sensors.

[vlad01]

That's pretty normal for the chain, slightly stretched but they have a fair bit of slack when new, that's what the dampener is for. That def wouldn't be causing any issues.

As for valves, ecotecs had 2 different sized intake valves, depending if it's pre or post 2002/3. Iirc the later were 40 thou bigger.

['quipt4it]

Hmmm...

['quipt4it]

...Also on the chain:
Holden say "Timing chain movement must not exceed 25.4mm"

[vlad01]

What most people don't know is we got the series 3 3800 internals before the US officially got the series 3, even though the block still says series 2. Different head casting, larger intake valves and powder forged rods.

I had a VY engine and it had all the series 3 goodies. Valve was 1.84"

[JohnDee68]

Thanks Vlad01 and quipt4it, I do appreciate your feedback and advise.

I have a feeling that I have a Vy series 3 engine in the car. As both the inlet and exhaust valves were of same size. The comparison valve on top of the current engines head, was an exhaust valve from a vt head.
As it goes I have been racking my head with all the possible things that may cause the econnomy issues.
I had a thought, about the injectors. The car idles smooth, it runs smooth it just has poor economy. So here is a theory I would like an opinion as to if it could be something.
The injectors are the 0280155777 factory Bosch injectors that I believe should be 21.44 LB/HR 219.85 CC/MIN 162 G/MIN 12 Ohm 3.5bar. Now in the TunerPro the Base Injector Rate (not exactly sure what that is) is set to 361.33 Msec/GRAM.
Is that maybe meant to be set to 162 rather than the 361.33 ? Presuming that the Base Injector rate is like the minimum amount of fuel the injector will inject each time it is cycled, then if that is so, could it be that the injectors are struggling to adjust the less fuel required ? It may also be why my O2 readings in TunerPro seem to me to cycle Lean/Rich quite at a rate I would think is rather excessive. But I am obviously no expert on this but am learning all that stuff as I go.