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Knock, blowout, or maybe both... [moved to new hesitation thread]

EfiniX

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Joined
Oct 18, 2012
Messages
647
Location
portland, or
Moving this from the General forum since I'm starting to go down the rabbit hole a bit more...

Seeing knock in 2nd. Ordinarily, one would expect this to be a fairly linear fix: reduce boost or reduce timing. Thing is, when I see the knock, I also feel a slight rumble... it almost feels like blowout. It's not like hitting a wall like when I was losing an injector, but it's noticeable. The question is that when I see knock, it's only 5-7 counts, so would I really feel that in the car? I know it's a question with many answers based on many things. Just looking for heuristics.

My vitals are: T3/T04 running ~21 PSI. I've already gapped my BR7ES plugs down to 0.022, but I can certainly go lower. 92-oct gas. plugs look good out of the car. Resistance on the 16-month old NGK plugs looks good. Didn't test the coil. ECU had it's caps replaced years ago, so that should be fine. I mean could it just be that I'm feeling 7 counts of knock? It seems like such a low knock count to actually feel...


Logs @ the link below. Pulls done on the 27th had new SD table values to clean up a slight lean condition @ WOT that I was seeing on the 26th.

click

Thanks!
 
Last edited:

EfiniX

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Joined
Oct 18, 2012
Messages
647
Location
portland, or
No responses yet, so I suppose you all get to join me on the troubleshooting journey. WOT pull this morning in 2nd great yielded promising results. Logs and discussion later today.
 
Joined
Jun 3, 2012
Messages
17
Location
columbia sc
you didn't specify your complete set-up. At 21 psi you need to running a front mount intercooler, bigger fuel pump, and better gas. I see your are running 92 octane, maybe try to find somewhere selling 93 or 94, or add a can of octane boost and see if that helps with the knock. When was the last time you changed the fuel filter? I would be looking at anything related to fuel and timing, cooling the charge air down, etc..
 

EfiniX

Well-known member
Joined
Oct 18, 2012
Messages
647
Location
portland, or
Fair enough. Here's the list:
ETS Intercooler (that's why my IAT's are nice an low)
JNZ racing manifold
New motor ~18k ago
-.50/.20 overbore
- 63DT 1g balanced pistons
- .25mm/.010 rods and mains
- 3-angle valve job w/ backup 6T valves
- vition blue valve stem seals
- BC1100 valve springs
- Oil port mod
- 3g lifters
- arp studs
SD conversion w/ omnibar MAP
custom exhaust heat shield
custom intercooler cold-side outlet heat shield
welded IC piping
Walbro 255 fuel pump
JNZ 9" plate oil cooler
3" Fujistubo Legalis R turbo-back exhaust
hi-flow cat
955cc FIC injectors
t3/t04 turbo w/ 54 trim and 60ar

other bits, but nothing directly relevant I imagine

New fuel filter w/ the motor (~ 2 years ago)
No 93/94 here in Portland, and I'm not ready to go the E85 route yet since there's only one station that carries it. Probably do meth injection first/instead because it's much easier to find methanol.

Does octane booster really work? I know I can buy race gas at PIR if it comes to that... For now, a slight timing adjustment seems to have helped out. I graphed where I was seeing knock across 3 pulls:







And I adjusted my timing from this:

img.php


To this:

img.php


The 2nd gear WOT pull I did this morning felt promising, but I was driving to the gym, so I didn't have my laptop hooked up to log. I'm sure I'll get a chance later today or this weekend and we'll see how everything looks. I expect with my mods and 92 I should be able to see at least 22-23psi without much hassle. Any more than that and I would want higher octane.
 

GSTwithPSI

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Jan 1, 2012
Messages
3,460
Location
SoCal
Sorry for the late reply man.

Honestly, I think you biggest issue is shitty fuel. It's going to be hard to make good power on 92 octane. I think that's also the main reason why you've seemingly been unable to get aggressive with your timing as well.

The tune could use a little work. Looking at your 2016.02.27-01 log, your WBO2 is reading almost a whole point richer than your AFRatioEST. You should adjust that out.

I can't tell much from the 2nd gear pulls; there's not enough good data. Most of the fuel data is skewed by the turbo spooling up. That's why 3rd gear pulls are much better for good data collection. As seen in your 2016.02.27-01 log (starting about 236.000 secs), once boost and airflow level off, it's a lot easier to see what's going on. You can clearly see there where your WB isn't lining up.

I can almost guarantee you're not seeing spark blowout, though. You may have an ignition issue, but it's definitely not spark blowout.

Overall, I'd say the tune looks pretty good. I really think fuel is your biggest problem. Go pick up a can of VP 110 and dump some in on a tank of gas. I bet you won't see a single count of knock.
 

EfiniX

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Joined
Oct 18, 2012
Messages
647
Location
portland, or
I believe that. I thought I found a unicorn just a short drive from my house, but when I arrived, I discovered pure (non-ethanol) 92-octane, not 93 or higher. From what I can tell, non-E 92 is just $2/gal. more 92 in terms of what it would get me since 92-octane is still 92-octane. In fact, I gotta figure that less ethanol isn't going to be a good thing.

So yeah, about my AFRatioEst... generally, the wideband tracks pretty close to where I have the target open-loop octane tables. So in this case... well I suppose this is my reasoning, and tell me if I'm wrong:

Let's take a section of my log where I'm showing 14.5:1 on my WB, 15.5:1 AFRatioEst, and 14.1:1 in my OLMO table. In this case, the WB tracks fairly close to the OLMO value through this part of the log, even though it's off by as much as 2.0:1 with the AFRatioEst. If I adjust the VE table to lean out at/around the cells where I see this, I'm taking the AFR towards the AFRatioEst and away from the OLMO value.




So what's a person to do? If I get the WB (actual AFR) to match the AFRatioEst through VE adjustments, I'm even farther from my target AFR's. I've been doing the opposite, only focusing on how the WB, AFRatioEst, and OLMO table match-up at WOT. And in fact, checking the log you referenced, I can tell with my current configuration that I've already adjusted my VE in/around the cells where the AFRatioEst and WB readings were off. But in this case, that's only because the AFRatioEst and the OLMO table seems pretty in-sync when I'm at WOT. I suppose that makes sense since at WOT, it's running in open loop.

I know during closed-loop, the AFRatioEst is a reflection not just of the OLMO table, but other bits and pieces, with the O2 sensor being no small part of the equation. should I just be trusting that the car knows what it's doing in closed-loop and try to get my WB readings in-line with the AFRatioEst value through the VE table?

After dropping my timing a tick, I'm pretty sure I wasn't seeing blowout, either. I'm going to gap back to 0.026 and keep playing with the timing. I was just shocked at how much I could feel 7-14 counts of knock in the car. When I can find my way out to PIR again, I'll grab some racing fuel. I'm already shopping for meth injection kits since that route seems more practical given the shitty, shitty gas around here.

Thanks!
 
Last edited:

EfiniX

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Oct 18, 2012
Messages
647
Location
portland, or
As a lark, I ran the SD adjustment tool on the long log I posted (2016.02.27-1) and it would seem as though all of the recommended adjustments are in the same area. Now it's a small sample set to be sure, but the fact that the adjustments are in the same area of the VE table is leading me to believe that the car "knows what it's doing" at cruise and the I should be tweaking the VE cells at cruise to get the WB to match the AFRatioEst value, not the OLMO table...



I'll do a proper low-to-moderate load-factor cruise and see if I can get a better fix on where my values should be. I'm happy with my open-loop values (I did make some changes that cleaned up the drift at WOT you can see in the referenced log). Don't mind getting the cruise AFR's sorted, now. Then back to timing and boost and all the other fun bits.
 

GSTwithPSI

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SoCal
Dude, you've got to realize it's damn near impossible to optimize your tune under every set of driving conditions. So, concentrate on getting it right when it REALLY matters; at WOT. I mean honestly, who gives a sh*t of your WB is tracking AFRatioEst in closed loop. I wouldn't even bother looking at that section of the log.

If you look at the section I pointed out when you did your pull (~236.000 secs), your AFRatioEst matches exactly what your OLMO table says it should be. Now, there's where you should be concerned, since your WB isn't mirroring AFRatioEst. I mean, it's not that far off, but I'd adjust it out if it were my car.

I think your main issue is you're a perfectionist. When you find someone who can tune your car perfectly, let me know...I think if you quit looking at logs every time you drive to 7-Eleven, you'd be fine /ubbthreads/images/graemlins/wink.gif

Concentrate on doing 3rd gear pulls that will net you good data to tune from. I roll into the throttle from about 3k to redline every pull. Just watch for knock, and get out of it if you're seeing 3-5 degrees. Then, make your adjustments, rinse, and repeat.

Here's a snap of a log from when I swapped to 1050's on pump. You want your WB to line up like so:
 

EfiniX

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Joined
Oct 18, 2012
Messages
647
Location
portland, or
Yeah, I'm probably not as crazy with this as I sound. Overall, I'm happy with my setup right now. It goes when I tell it to go, and it doesn't do anything ominous like leak fluids, foul plugs, or blow weird smoke out the back. My current bit of car hypochondria is the result of some stumbling at WOT, stumbling that signaled the end of my last motor (which, to be fair, came to me broken).

Truthfully, I've never actually run the VE adjustment tool, so why not. It's not like I have to apply the changes it suggests, right? As for WOT, it sounds like I'm already on the right path. Do some pulls, check the logs, make VE table adjustments to get the WB lined up with the AFRatioEst. Pull, log, adjust...

BTW, you're running E85, aren't you? That's a nice bit of timing you've got at max boost!

Thanks again!
 

EfiniX

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Joined
Oct 18, 2012
Messages
647
Location
portland, or
wowja. is the difference between 92 and 93 really the difference between me running 11* at 21psi and running 17*? I'd love to run that much timing!
 

donniekak

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Jan 1, 2009
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surprise az
Not sure about 92, but going from east coast 93-94 to west coast 91 I usually have to drop a few psi of boost, and 5-8* of timing.
 

EfiniX

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Oct 18, 2012
Messages
647
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portland, or
Meth it is. Not sure why there is no 93 in my market 😠
 

EfiniX

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Joined
Oct 18, 2012
Messages
647
Location
portland, or
A fascinating development. Starting a new thread since this one has great info, but no longer seems to be directly relevant to the issues I'm trying to work out.
 
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