VS Commodore V8 ute ECU troubles

[charlay86]

If the gauge reads correctly it probably indicates that the calculation in the adx is based off the coolant sensor voltage instead of the value that the pcm has calculated, in which case I would expect to see what you have described.

[SPArKy_Dave]

Well at the moment, the Coolant sensor values seem to be normal, at around 95Degrees and 1.88 Volts.

At idle, the PCM is in Open loop, with Rich AFR, a target AFR of 14.0 and an O2 reading of around 750mv

Once the TPS percentage is over 4.3%, the PCM immediately changes to Closed Loop, the AFR flicks between Rich and Lean, the target AFR value jumps to 14.7,
and the O2 reads around 400-500mv.

Sometimes there are frequent connection errors, but if I stop and re-start the engine, those errors can become more or less frequent, or sometimes stop altogether (ie, a perfect connection).
Throughout all of this, the OBD plug and USB connections have remained plugged in.
The PCM is still in its factory position hiding behind the plastic kick panel. It hasn't been touched though any of this fault finding.

[SPArKy_Dave]

Additionally, the car runs a bit rough at idle.

When watching a monitor graph, with TPS v's target AFR v's O2mv - I can clearly see the O2 sensor reacting, when at 14.7, and in closed loop.
The O2 voltage rises and falls always around the 500mv area.

When the PCM goes open loop (at idle), the target AFR drops to 14.0, and the O2 line graph rises to about 750mv, and hovers at that value.

I have also verified the TPS -
closed throttle shows as 0% and 0.57V
WOT shows as 99.61% and 4.31V

[charlay86]

Can you post up a log file of the car misbehaving.

[SPArKy_Dave]

Would you consider the above values, a mis-behaving car/PCM?

or the values when the CTS says around 30Degrees, but the car is clearly at operating temp?

[vs ss]

Hi i had the same stupid readings etc when i made the mistake of buying the ebay aldl could never get a clean read .
So the best thing i ever done is throw it in the bin and buy one of vl400s and you never look back.
But anyway i had a 5l stato doing the same thing and took a while to find as there was never any fault codes and every time i logged it the car would not play up.
In the end i replaced the coolant temp and still played up till one day a grabed another pcm and bingo 12 months later not an issue.
Probably not related but i will just let you know incase you have the same hair pulling fun i had

[charlay86]

Those values sound normal to me, but if it is idling roughly as you say, something else may be the matter.

[vs ss]

Yep they seem right to me as well

[SPArKy_Dave]

I will attempt to record the PCM values, when it's doing the Funky Monkey, and post up the log.

When it's playing up, I can tell without even connecting Tunerpro, as the trans will not lock up, even at 100km/h along the freeway.
It also becomes a real slug to drive.
Revs are slower to pick up. Almost like you've got a heavy trailer on the back.
Fuel consumption is astronomical - 25-35ltrs /100km.

If I was to Re-set the PCM during one of these 'episodes' (by pulling the engine fuse), the vehicle is immediately transformed - like driving a new vehicle again.
Plenty of power, no slugishness etc................. for about the first 15mins.
Then it hits a wall, falling back into it's old pattern.

[SPArKy_Dave]

I might also add, that the low CTS reading, has been previously verified by an independent pro scan tool. (it said 24 degrees.)

Can't remember the name of it, but it was orange, with a monochrome screen 3/4 the size of an ipad, chrome/black buttons on the R/H side,
and a case full of adaptor leads.


The PCM also throws error code 16.
It's the only code. (apart from 12)