A series of events (for you tuner troubleshooting types...)

[~Barn~]

Wait so you were getting 6-7 degrees of KR at WOT while using 85 octane and you didn't think that was a problem?? I thought you were using 85 because you weren't seeing any KR.

But yea, I just had a problem with my fuel trims skyrocketing and it ended up being a vacuum leak.

Didn't happen all the time. Some times I could do WOT pulls all day long and would maybe get a couple hits of a degree or two. But yes, there were those days when it would jump into the 6's and 7's for a moment, but it was never consistently like that.

Even with a couple more days of data-logging on the 91 cctane, I've seen a couple hits in the 3* range. It's funny though, because these occurances seem to be at more mid-throttle, than WOT.

As for the LTFTs, they finally settled down to a stable +5 yesterday. I think I just needed to drive around more on the new plugs, for the computer to sort itself out. No leaking or disconnected vacuum hoses, that I could surmise.

Time to put my map back on!

[~Barn~]

Well... not that anybody is particularly riveted to this thread still, but more analysis has yielded some more info. I decided to put my off-the-shelf Cobb map back into the ECU, now that my LTFTs are stable, and see what's what. This first tank (higher) octane gas is pretty much cashed, and it was a hot one today.

For starters, 91 octane gasoline and 1-step colder sparkplugs alone, have not completely "eliminated" KR on my MS6. They have however, brought down the severity of it, when it does happen. Previously peaking in the 7* range I now seem to be peaking in the 2* range. Also worth mentioning, is that about 2/3 of the instances of KR that I'm experiencing now are at non-WOT conditions, which is reassuring.More importantly though, I am now getting it exponentially less frequently.

For reference, and for a more concrete idea of what I'm talking about, I data-logged roughly an hour and 12 minutes of driving today; some sporty, some cruising, some stop&go, and some flat-out. My Cobb took 4320 data snapshots during that time, and of those 4320, I had KR hits 23 times. 18 of those times, it was less than 1 degree, and the other 5 times it averaged 1.6*.

Now step back a few weeks, and I pulled up historical data logs from before the changes. I looked at a different section of 4320 data stamps, and on those logs, there were 190 instances of KR. Of those 190 instances, the average was 1.9 degrees of retard.

So yeah, I don't know if the chicken or the egg came first, but between these new plugs and the 91 petrol, I have to admit, I do love what I'm seeing. And again, this is back on an aggressive Stage 2 map, with peak boost targets at ~18[size=84]psi, tapering down to ~16.5psi by redline, (+/- 1.5psi). And my LTFTs at idle are holding stable at +4.35[/SIZE]

[size=84]I guess the only thing left to do now, is keep trying to bring my boost temperatures down, as best I can. I'm very pleased though, with where I am at right now.
[/SIZE]

[erod550]

Glad your car is running better. Most of my KR comes in part throttle situations too, with the large majority of it happening right as the car is reaching normal operating temp. When it's warmer outside I do get 1-2* of KR very occasionally in 3rd or 4th at WOT. When I got my protune it was around 50 degrees outside so I should go back and get a 2nd map made on a hot day to account for the higher boost temps.

[tbot]

the part throttle knock is actually the ecu pulling timing (and fuel) to attempt to acheive the greatest fuel efficiency, its not really knock at all.

with that outa the way, glad ur fuel trims settled.

also, with the higher temps, it takes a higher boost to reach target loads, so yes these cars need a summer and winter tune to run at optimum levels. on the other hand, u couldmjust tune for the higher temps and realize that u wont hit target boost levels because the car doesnt need it. te final option is to run an ext wg and run off the gate spring for boost control, the safest and simplest way to maintane consistent boost levels.

[~Barn~]

Glad your car is running better. <Snip..>

And truth be told, it's not that the car was really even running bad, before. I think I tried most all of this out of my own curiosity, to see if and how the numbers would change. The plugs I figure are wear-parts anyway, and I don't think the previous (original) owner had ever changed them, and the 91 octane, was just impulse.

I think the final test in my little stoichiometric dissection, is going to be to run 1 more tank of 91 through her, and then go back to 85. I don't know what will happen, but I have a gut feeling.

My guess is that I'll see a small increase in my KR numbers (both peaks and frequency), but that they'll still be way down from where they were, pre NGK swap. That said, I also think I'm gonna see my ECU start scaling timing advance back, and the car isn't going to be as powerful.

[Cue personal dilema music]

[erod550]

Just remember that the Cobb maps are designed for 91 octane so are more aggressive than the stock tune. I would strongly recommend not running 85 with a Cobb OTS map.

[tbot]

I don't think the timing is that much more advanced on the Cobb maps vs a stock map. At the same time, if you can figure out what RPM and what throttle input you are getting that part throttle KR, you can go in to ATR and at the are pull back timing slightly and actually tune out all KR whatsoever. I was able to do that in my car and would only get KR when I ran out of meth hehe. So there is a way to eliminate it completely and its really not that hard at all.

[erod550]

Yea I think I'm going to try adjusting my protune like that. Just need to get some logs and it's tough because the KR doesn't happen every time.

[tbot]

Make sure MAC unlocked your protune so that you can edit it in ATR otherwise you won't be able to just FYI

[focoms3]

can't believe you run 85 octane.. especially on a Ap stage 2 map!! and i was worried over 91 octane at some gas stations being worse than others ($hell)