charlay86 wrote:The two banks of the engine have individual adjustments so the voltages will differ slightly, but due to the way the integrator algorithm works they should look similar.
The idea is that their voltage swings above and below of 450mv (stoich) as the mixture changes from rich to lean.
when the PCM is operating in closed loop mode it deliberately makes small changes to the amount of fuel injected to force the sensors to swing from rich to lean and vice versa.
if the sensor's voltage doesn't change, the PCM makes another small change in the same direction as the last one until it does change, It then remembers this value for the current engine RPM/Load value.
That is how the PCM "learns".
Thanks for the info.
Now i'm not sure how to work out if there is anything wrong with my engine.
Are there any values that i should keep an eye on for fuel consumption.
I've noticed when viewing the fuel consumption figures vs TPS Percentage. I've attached a pic.
dmenace wrote:
Now i'm not sure how to work out if there is anything wrong with my engine.
check for fault codes for a start, there in the data list view. If that's all good then check all your sensor outputs in the datalog and see they match what they would normally be running at, for your o2 sensors have a look at crosscounts rather than voltage. As crosscounts will indicate lean/rich swings, when o2 get old there lean/rich swing response will not happen or be very slow. Under load so 30% throttle you would look for >5 crosscounts.
Detonation is due to it being lean.
if you setup a long term fuel trim (Z) history table vs RPM & milligrams per cylinder (X & Y), you'll notice that there is 22% fuel correction peaking at around 375mg/cylinder & 2200-2400 rpm.
The detonation also happens to peak around the same load conditions....
Neither is more accurate, they are just calculated differently.
"History Average" uses a fixed number of samples (defined in the adx editor for the history table) for the calculation whereas "Running Average" uses all of the samples aquired to calculate the average.
In the case of long term fuel trims the result will be quite similar for either of them.
The light detonation tends to confirm that you have an actual lean condition.
Does this car have extractors / aftermarket exhaust or some other modification by any chance (previous owner may have installed something)?
It could also be lean if you have an air leak, malfunctioning MAF, restricted fuel system, dodgy fuel pump (run her dry recently?) etc.
have you check the stuff I listed a page back or 2?
I have seen a number of things cause fuel consumption and running lean conditions in these cars.
have a look at your air intake duct after the MAF. I have seen holes develop on the underside of these ducts big enough to fit your hand in but just looking at it your couldn't tell until you squeezed the duct and looked underneath.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.