Excessive KR

[stripSHO]

I've been fending off knock with the AO ever since it got cold out (20's and 30's here). Coincidentally it actually started the exact same day that @Lostneye started this thread.
OAR had been perpetually anchored at .74. I thought I had it nipped after my 6th different 93 octane choice allowed me to massage it back down to -.96 the other day. But alas, tonight I stomped it for the first time on this tank and was greeted with max KR within about 2 seconds.

It's annoying as **** because it seems only a select couple points in the map are ruining the party for the whole RPM range. Main culprit for me is around 2000-2500 when rolling into the throttle. Once I'm past that KR drops rapidly to -3 or lower but then I get hit with another light knock event just soon enough to keep the OAR from updating.

 

[Angrymongoose]

My KR only made it to -3 on the AO when I was purposely focused on doing so.

Put in S shift to 3rd or higher and at 1500 rpms give halfish throttle. Couldnt keep the -3 for long and certainly not enough to bring the OAR back to -0.96. Though I never maxed the KR on the + side. I dont even know what a max number is for that.

Where I get positive KR seems to be the same as you, but even after getting beyond that say to 3k rpms or higher my KR will go to 0 but not negative usually.

On the stock tune though it seems to be doing much better. I suppose winter gas is a possible culprit. I have more plugs laying around I may try those, and maybe the new msd coils will help when they get here.

Unfortunately I dont have something else I changed to try to narrow it down. The tune is the first change Ive made to the car.

 

[76FoMoCo]

I'm on a AJP tune and see the same as you guy are talking about soo I will change mounts first.

 

[b4black]

Winter gas in NOT the problem. 93 octane is the same summer or winter.

Knock related to the tune is likely caused by too advanced timing, too lean AFR during power enrichment (wide open throttle), or too much boost.

When you scan, do you look at these parameters? They at the most important. Unfortunately, with tunes uploaded thru SCT, I don't think you can't tweak these on your own.

 

[Angrymongoose]

I haven't looked at them in depth myself, but at quick glance I didnt see anything wildly out of place. I can't change anything at all on the tune myself though. I would have to have Gearhead change it. I am going to send them a few datalogs to check.

I doubt its AFR during enrichment though since there is almost never an issue at WOT, only part throttle.

 

[FiveLeeter918]

any updates?

 

[Angrymongoose]

I just emailed GH last night, I didn't expect them to see it till this morning. I haven't heard back yet but I imagine itll be later today.

I have a new set of plugs showing up Wednesday and I'm gonna quadruple check the gap, then throw them in. I figure that's a simple easy thing to do so we shall see what happens.

I did get my PPE catless dps on this weekend so that was nice. They are a bit raspy at certain rpms. I didn't expect that, gonna crawl under there later this week and make sure everything is tight.

 

[FiveLeeter918]

if you get a revision for them with proper VCT settings for downpipes, it will quiet them down quite a bit.

 

[Angrymongoose]

That's good to know, thank you.

 

[FiveLeeter918]

That's good to know, thank you.

sure thing! VCT can completely change the way a car sounds at different RPM ranges.

 

[Angrymongoose]

Well, got a response from GH.

"This is how OAR is supposed to work. It is calibrated differently than stock. It will have a different reading than the stock file and thus how we calibrated the auto octane. If he is getting positive KR at part throttle, it is doing exactly as it should. Has he tried some better or different fuel?"

So apparently I just have to live with a -0.50 OAR being the best I can get from this tune. I was kind of disappointed in the response as it ignored the WOT part of the email and kind of gives the impression that no one opened the datalogs.

Since changing the spark plugs I don't see near as much knock at part throttle anymore. However, WOT will still see knock up to around 7.5 sometimes, to the point Im worried to floor it and wind up killing my OAR. Ill give yet another gas station a shot, but I don't have high hopes for that. Now I'm counting on the MSD coils fixing the rest of my problem.

 

[SHOdded]

Sorry to ask, i am sure it has already been asked, but what brand fuels specifically have you tried (all 93 right)? All E10 or E85 mix or ...? Tried mixing in some race gas concentrate, play with the amounts and see if it has ANY effect on the OAR?

 

[Angrymongoose]

Casey's gas stations and Sinclair are the only ones in town with 93. It is all E10 93 around here. I don't know who supplies Casey's fuel unfortunately. It seems in the short testing I've been able to do that the Sinclair is better.

I have not mixed in any E85 yet, hadn't done enough research to know if I could mix that safely especially during the winter. If I can ever get to the place in town with race gas I may try that.

So far the plugs seem to have made the biggest difference, but even they still leave me with too much knock for comfort at WOT.

 

[FiveLeeter918]

dang man...

 

[SHOdded]

I would try adding the RGC at various concentrations, but first get an ethanol tester to see really how much ethanol is really in the fuel at Casey/Sinclair. That is an ongoing problem when you travel, even at name brand stations, which vary in gas quality by location. After you have determined ethanol concentrations, we can see if RGC would help anything.

 

[stripSHO]

Well, got a response from GH.

"This is how OAR is supposed to work. It is calibrated differently than stock. It will have a different reading than the stock file and thus how we calibrated the auto octane. If he is getting positive KR at part throttle, it is doing exactly as it should. Has he tried some better or different fuel?"

So apparently I just have to live with a -0.50 OAR being the best I can get from this tune. I was kind of disappointed in the response as it ignored the WOT part of the email and kind of gives the impression that no one opened the datalogs.

Since changing the spark plugs I don't see near as much knock at part throttle anymore. However, WOT will still see knock up to around 7.5 sometimes, to the point Im worried to floor it and wind up killing my OAR. Ill give yet another gas station a shot, but I don't have high hopes for that. Now I'm counting on the MSD coils fixing the rest of my problem.

At 7.5 KR you need to be much more worried about killing a piston than losing timing. It's an unfortunate situation but until you figure out the culprit you need to let that OAR number fall where it may.

PM me your log and I'll see if I can see anything

 

[b4black]

I've done a lot of testing and E10 is nearly always dead on 10% ( I once worked is a fuel testing lab). Every terminal is set up for 10% on the nose. It doesn't vary like flex fuel. If you suspect something with the fuel, fill up somewhere next time, because the odds getting bad fuel once is very small and twice in a row almost impossible.

And brands like Casey's buy there fuel on the open market. It will meet the posted octane. It's highly unlikely fuel is your issue. And you can certainly blend in a few gallons of flex fuel safely.

Someone really needs to look over your scans, because 7.5° is way too much.

 

[Angrymongoose]

Update.

First, I called GH today. Mostly because I wanted to be sure I explained my concerns and what was going on clearly to them. I am not always great about that in email or even on here, especially right now between the holidays, extra busy at work, and everything else.

Matt did in fact look at the logs does believe the gas is not quite up to par. Between the winter blend and the only two brands tested that is what they believe.

I asked if anything else looked off or unusual and they said no. They gave me a direct email for Matt to send some more specific datalogs to if needed.

They suggested trying a few gallons of e85 to bring up the octane. I found a station here in town with e70. I did not personally verify its content, but I know a few others in town that use it and vouched for this station being e70 consistently.

So I put in 3 gallons and topped off with 93 e10 again. In a 10 minute or so drive it seems to have solved the problem. Highest knock I saw was 1.25, and saw more negative knock than I had been on the tune.

It appears the culprit may very well be the gas. I'm adding the one Sinclair and Casey's to the no go list. Unfortunately I'm pretty sure my only other options are different Casey's around town.

 

[b4black]

Matt did in fact look at the logs does believe the gas is not quite up to par. Between the winter blend and the only two brands tested that is what they believe.

The octane of a "winter blend" is the same as a "summer blend". Winter gasoline has a higher vapor pressure, but the octane is identical.

Casey's gas stations and Sinclair are the only ones in town with 93. It is all E10 93 around here.

So are you saying that the Casey's and Sinclair are ethanol free (E0) and that all other stations are E10? If that's the case, then use the E10. Direct injection engines respond to ethanol different that other engines. The octane ratings are the same, but the engines used to rate the octane are not direct injection (carbureted). The DI engine will see an additional benefit from the ethanol as it cools the air as it's compressed (heated). Ethanol has a higher heated of vaporization than gasoline.

In a DI engine E10 93 > E0 93.​

 

[Angrymongoose]

All 93 here at all the Caseys and Sinclairs is E10.

Whether the octane rating is the same or not between winter and summer blends it still doesn't perform the same way. I agree with GH on that one.

Plus given that adding E70 to bring up the octane solved the problem I would say that both the Caseys and Sinclairs gas sucks. Whether its the winter blend or just crappy gas is one of those distinctions without a difference at this point.