Log analysis for MPS6

[devious]

I applied the Octane High Load tune yesterday and re-captured logs.
3rd gear pull was from 654 secs which resulted in 170kW and 364Nm (atw).
AFRs look good.
Is there anything else you can see in these logs that would make you think the car is not running as good as it could?

[mituc]

The logging resolution is very low. You should remove anything related to the secondary O2 sensor, that one is very slow and holds up everything else.
Things look decent, you get a bit of ignition retard because approaching or exceeding the boost limits (and load limits) here and there, but that can be tuned out.

[mituc]

Ok, so your car has a lot more potential and and OTS tune will not get you very far. I can't leave you like this, but it's also up to you. Purchase the versatuner full version and I can send you a tune that will not overboost and will extract more power safely.
Also tell me exactly what gas are you using right now or you intend to use, and some specs (you seem to be from AUS, so you need to tell me if the 95RON or 98RON or whatever you're using there is E5 or E10, and things like that). Also send me a full list of all the mods that you know of and I will PM you a proper tune.

[devious]

That sounds like a great offer. Might take you up on that but I'll need to check out a few mechanical things first.
Don't feel the car is running clean yet and it hunts when cruising at 100km/h so I need to find the cause.
Got it booked with mechanics in about a week so I'll see how that goes first.
I might record some logs when I'm on the hwy again to see if we can identify anything suspicious.

[mituc]

Since we're in a log analysis topic... just post a log with that problem at 100Kmph happening.

[devious]

Here is a log I captured today whilst cruising around 100km/h.
The car feels like it has a slight surge every few seconds.
The road pitch did change every now and then which could impact the readings but the last 10 seconds was very constant so should be a good area to look.

The RPMs seems steady, however there are visible fluctuations in:
- mass airflow
- accelerator pedal position
- boost pressure
- fuel rail pressure
- ignition timing advance
- short term fuel trim

Any suggestions on what I should look at first?

[devious]

Hold that thought... I think I may have found my issue(s).
After cleaning the throttle body I then pulled the spark plugs. (see pics)
I'll replace these bad boys and see if the hesitation still exists.

[mituc]

So remember:
1. the OEM NGKs should be changed every 60k miles/90k kms, but they're actually good for only 45k miles/60k kms.
2. The Densos are a tad weaker so replace them at 1/2 of that;
3. if the spark plugs are one step colder avoid excessive idling especially in cold weather.
4. at that much soot in the cylinders I'd start wondering if the oil changes are done at the right time interval and with the right oil. Assuming you don't use the car just to keep it idling and warm people up in the cabin, that level of soot is a little too far from what anyone would expect.

[devious]

Thanks for advice about the change intervals. I didn't know there was a big difference between the brands.
I ended up getting Denso ITV22's as they were half price of the NGK's. (stayed with the OEM heat range)
I don't know what the prev owner did to have plugs like that, but I agree, something was not being done right for that much carbon build up.
Installed the plugs tonight. Car runs much cleaner. Doesn't appear to feel bogged down as it did before.
Will try to record another run in the coming days to compare outputs.

[mituc]

I ended up getting Denso ITV22's as they were half price of the NGK's. (stayed with the OEM heat range)

ITV22 are one step colder than OEM (same as NGK 6510/6511). ITV20/NGK 3787 are OEM heat range.