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

[JohnDee68]

O2 sensors must swing around quickly. It's the ECU responding to the output. They get lazy as they die and that is a major cause of high fuel consumption.

Hi Charlescrown and guys,
I am still trying to understand all the signals and feedback to the PCM. So please excuse me if i am not as good as many with this. But I look at how the injection system & O2 sensors are meant to work is like this:
The O2 sensors report back to the PCM as to how rich or lean the exhaust is. So according to what is fed back to the PCM then the PCM will calculate and adjust the fuel change required to try and maintain the O2 readings back to mid range (being a perfect fuel burn). So, in theory if the fuel and air are mixed perfectly at combustion, the O2 sensor readings should be steady at "mid" range being the perfect burn, not swinging High-Low-High. Well, not as much and in an ideal world of course. It will also depend on the O2 sensors if they actually change their voltage feedback according to linear or are just High/Low feedback to the PCM. I am led to presume the O2 sensors are linear and therefore the PCM will alter fuel trims by the percentage off the mid range O2 sensor readings to bring the O2 level back to 0.5v, being a perfect fuel burn.
So, with that in mind, if the O2 sensors and STFT, read as they do on my logs, there has to be either a wrong mixture of air/fuel going in to the combustion chamber due to injectors, or air flow. The same result can be also from a no spark condition, but that isn't the case in my situation.
I base this on my understanding as to how EFI systems are designed to best maintain perfect burn every time.
So if I am correct and the linear O2 sensors give feedback to the PCM and the PCM can calculate the fuel trims accordingly, then the O2 sensor feedback's on a more efficiently burning engine, should look more like a sine wave or a minor stepping square wave rather than a saw tooth wave. It is almost like it is changing its fuel variants too largely where it should be smaller steps changes. This I don't know yet, but might be changeable in the "tune" via TunerPro ?

Appreciate your time and feedback.

[JohnDee68]

... 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...

Dang that is a wide spread between those two fuels.
Regular ULP is rated at 91 RON (Research Octane Number), E10 is 94 RON. Research has shown E10, as of it's lower energy (lower calorific value), usually returns less mileage than non Ethanol blended fuels.
You would expect to return slightly higher mileage from the 'Regular' fuel, even though it is lower in octane than the E10.
I wonder if your situation is knock (and retard) related more than anything else suggested.
Your engine is disassembled now?
A good comparison would be to try a higher octane 'Premium' fuel.
On a different note, you aren't confusing intake with exhaust valves are you?

Hi quipt4it,
Yeah, it has been a nightmare. I run the E10 as it gave me a more efficient power/economy initially when I tried mixing it 50% with regular as a way to try clean the injectors. It seemed to rune well and like i said 200km nearly more in the tank than previous 100% regular. I then decided to try and see if it was just that it cleaned the injectors or not. So i went back to a full tank or two of regular and the economy declined again over the next couple of regular unleaded tanks. Some went as low as a struggle to go 450km on a full 75 Lite use. I then went back to a full tank of E10 and instantly on that tank pulled more around the 650-720km a tank (75L). So I then kept with E10 and noticed it still wasn't burning right and started to alter (test) little changes to the PCM tune AFR for E10. Yes I got results accordingly, but still didn't get what I felt it should and also noticed things like a drop in its power as well.
I have been going over my history more of what I have done, what has been replaced and what is still from the original engine now still on the current one. I am thinking that it could be, taking in to account the readings of the logs I have from TunerPro. That it could be injector issues, possibly just requiring another clean and service, but it might be time to replace them as a set. The history is I am on the 3rd engine, and the car has done 505K over the 3 engines, and 3 of the injectors are originals and 3 are a mix from an old VT & the Vy refurbished engine which is now the engine in the car. At the time i cleaned and tested all the injectors and they were fine at the time I fitted them. Though that isn't to say they didn't and aren't performing 100% from day one of the engine being put in my car. I am thinking that poor injectors which are almost all equally as bad, could cause "knock" and poor economy and power loss, but am not 100% sure of that yet.
No the motor is in the car and has been for about 3 years now, I think. I am not sure what octane range i can safely put in the motor, any way i can confirm what I can go to without blowing it up?
Now you have me thinking, i may be confusing the exhaust and inlet valves. I am not sure what i said previously, but i am pretty confident the increased size valve on the current engine were the inlet valves. Looking back over pictures at the time of the refurbishment, I cant see what is the inlet or the exhaust. So no, i cant be 100% sure what was what now. Though I am pretty sure it was a larger inlet valves on the current engine.

[JohnDee68]

It's hard to know what it actually is or if it's a multitude of things all contributing. My old VP vacationer used to get about 7L/100 but as the engine got a lot of Ks on it it increased to about 10-11L/100 by the time it had 400K on the clock. Interestingly that was even with perfect tune and knock retard disabled.

But one thing I did notice was severe lifter rattle at certain rpms, they were bleeding down so perhaps I was loosing valve lift and timing. The engine was a little down on power from 90K on the clock when I first installed it but not a massive amount, maybe 10-20%?

My new VP auto with 120k stock gets way better economy than my old shitbox VP with perfect tune, knock disabled and manual, with lean cruise, but the engine had a very hard life. Overheated badly by my nephew, drove it 40km with no coolant and seized it 6 times on the way home and the valve springs are weak I think as it struggles to get power over 4k rpm, rolls over a lot compared to my other cars. Now it's consuming coolant so it's on it's last legs. The economy has deteriorated to about 12L/100 at the moment.

Vlad01, that is interesting and could be a vital thing for me. Though I am just guessing as i wouldn't know how i can test for weak lifters? But I replaced the lifters in this current refurbished motor, so presume they are ok?
My issue is, if I think back to my older cars with carby systems....yes i am that old . Well with those engines, using vacuum gauges, timing lights, dwell meters, I could confirm that things like mechanical issues were the cause or not. Using same tools today on this car, the vacuum gauge shows me signs of either poor mixture or spark timing. Nothing like valve springs weak or late vales timing etc. So hence why I am at a bit of a loss. Also, back in the days, I had funds to throw parts after part to resolve issues, I can't do that these days at the moment.

[JohnDee68]

Vlad01 & quipt4it,
Is there a way to disable the Knock retard on the Vx ? So I can test drive to see if it is the issue? Or would that be an unwise thing to do?

['quipt4it]

VX uses flash program as you know.
You have the cable, just download the OSE Flashtool (if you don't have it):
download/file.php?id=9542
There is (or should be) a term; RDSC - Disable If Coolant < Than This. Set this to say 155.
You would flash the whole bin the first time (with Flashtool), and any further updates can be cal (calibration) only flashes.
Here is a video on how to flash a VX/VY PCM:
https://www.youtube.com/watch?v=rsIQPc_oe1Y
NB: "VATS is Disabled on Flash Pcm's If you want vats security re-enabled you must have the PCM and BCM Relinked".

Drive carefully, especially if you feel you have genuine engine knock. If so, may be best to revert to previous settings lol.

['quipt4it]

Now you have me thinking, i may be confusing the exhaust and inlet valves. I am not sure what i said previously, but i am pretty confident the increased size valve on the current engine were the inlet valves. Looking back over pictures at the time of the refurbishment, I cant see what is the inlet or the exhaust. So no, i cant be 100% sure what was what now. Though I am pretty sure it was a larger inlet valves on the current engine.

valves.jpg (235.83 KiB) Viewed 1767 times

[delcowizzid]

Rsdc is not the knock control its just for anti bunny hopping when manual smooths out throttle transitions. The o2 sensors swing rich and lean over and over its how they work if they swing to far the ecu adds to the short term fuel trim to pull them inline. The knock sensors will go off with wheelspin or if the exhaust or engine touches the body or kframe

['quipt4it]

Doesn't RDSC/ESC control knock/retard parameters? Delcowizzid, are you referring to 'Tip-in Bump Spark'?
From the FAQ:
"Q. How do I enable or disable the knock filter?
A. There is no direct flag for this. Instead edit the scalar ESC params - Coolant temp enable. The knock counts will be used to pull timing above this temperature. To disable the knock filter (when it or the knock filter is not physically fitted) set this value to the maximum. To enable it again, set it to the default value of 56 degrees C."

[Charlescrown]

I know what your saying but that's not the case the 0.5 volts is determined from an average of the o2 sensor swinging around. There are so many variables that take place it's impossible for the system to supply and burn a perfect mix hence the role of the O2 sensor. It's the ECU responding to changes from the O2 sensor that you see taking place. I found out about 15 years ago that as they get old they become lazy and the outcome is slow to react to change. The vehicle was a Holden with Delco and it had been to several workshops and had quiet a few sets of plugs, leads and the injectors replaced to fix a high fuel consumption problem. This was over a two year period and nobody thought to look at how active the o2 sensors were because there was no fault codes displayed. It was then that a company called Coda got the car and straight away found the problem.

[vlad01]

I just set ESC to max temp and that works. I found using the ignore knock table doesn't work at all. Seems to be a bug, at least in 12P