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Why am I knocking? [Link log]

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BurrowZ

10+ Year Contributor
836
5
Nov 28, 2010
Duluth, Minnesota
Alright, I'm no ECMLink pro. In fact I only just started tuning with it a few weeks ago. I followed these guides:

http://www.dsmtuners.com/forums/articles-tuning-ecu/262460-basic-dsmlink-tuning-guide.html
DSMlink MAS/MAF Calibration Page
GMAF Calibration for LTFT

Now, a few weeks ago I had it tuned to what I thought was a safe tune, no knock and no added timing @12psi. It wasn't fast enough for me though, and today I went out and raised boost by 4psi using my AEM TruBoost. Attached are some logs, and mod list is up to date. It just comes out of nowhere to me. I really need your help!

Please note I was doing 2nd gear pulls since I'm an auto.

And I had to let off early in the second log because some moron in a Monte SS had followed me around town and had gotten into the oncoming lane either trying to pass me or race me. I wasn't trying to make anything think I was racing them and wasn't trying to put anyone's life at risk. But you still see the knock and get the idea.

If it matters:
It was 63 degrees out today.
Fresh rebuilt (200 miles) E316G with S16G hotside, eBay 3" anti surge 20G compressor housing and wheel, being fed properly and return line is unkinked.
91 BP pump
Pulling air from stock SMIC location
Stock bottom end@97k
Exhaust cutout was CLOSED, so 3" exhaust all the way to stock muffler
Thanks for the help!
 

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You sure your Wideband is reading exactly what the logs say?

Also, I wonder what you AIT's are really... .
 
Is BoostEst correct? If so there's a few things that are uin-known as My1GDSM said, but the only thing i can think of is that 13* although reasonable to be correct for MBT might be a bit high depending on IAT's, the level of carbon buildup that may be in your engine and how good that 91oct pump really is.. at least that's if your boostest of 26-30psi where the knock starts in log two is correct. you may have to back down the timing curve by 3* and see if that helps keeping all else the same (assuming the AFR"s are correct also)

Reading DSMlink logs can be confusing because you have these variables that may or may not be the actual reading of what it says it is (boost and AFR being the main two that drive me nuts) I wish there was a way to make the AEM just the logged voltage in mode "P00" on the WB02, that way i cna convert it on a spreadsheet.. as foor boost est, not sure how to get around the user responsibility to have it calibrated correctly

EDIT if the WBo2 (AEM one) is correct i'd lean it down to abut 11:1, i've always picked up knock when as rich as 10-10.5:1
 
Is BoostEst correct?
Yes, I calibrated it correctly and watched my boost gauge and tach(video recorded with phone ;)) then compared with the log. Everything matches.
depending on IAT's, the level of carbon buildup that may be in your engine and how good that 91oct pump really is.. at least that's if your boostest of 26-30psi where the knock starts in log two is correct. you may have to back down the timing curve by 3* and see if that helps keeping all else the same (assuming the AFR"s are correct also)
Well, I ran Seafoam through it not too long ago. Maybe a month or two ago. I would imagine IATs are solid, not too high. All my heatshields (except lower) are on, and like I said I'm pulling air from the stock SMIC location on a nice 63* day with a fairly efficient FMIC. I will have to try backing it down about 3* then anyway.
Reading DSMlink logs can be confusing because you have these variables that may or may not be the actual reading of what it says it is (boost and AFR being the main two that drive me nuts) I wish there was a way to make the AEM just the logged voltage in mode "P00" on the WB02, that way i cna convert it on a spreadsheet.. as foor boost est, not sure how to get around the user responsibility to have it calibrated correctly

EDIT if the WBo2 (AEM one) is correct i'd lean it down to abut 11:1, i've always picked up knock when as rich as 10-10.5:1

Alright, I was just a little afraid to keep leaning it out since it was already knocking enough. I know there is rich knock but i didn't think 10.8:1 was all that rich enough to cause nearly 5 degrees of knock retard.
 
My car (although on e85) will knock at anything richer than say 11.8:1. Back when I was on pump running 20-22psi, i commonly aimed for 11.2 - 11.5:1 and ran 14* timing that ramped up to 16 slowly by redline. That was on the original 7.8:1 comrpession ratio, when i was on the stock 2g engine i had to run 2-3* less on 91 pump.
 
But will you really see that much knock with an A/F only a maximum of .5:1 richer than your target? That's my only concern otherwise I would have continued with my tuning today.

I might just have to wait the couple weeks to my birthday so I can ask the wife for some bigger injectors and go corn juice.
:)
 
Well, think about it this way, when you're right on the threshold of knock (your 2-3* is about there) a "half a point" is the difference betwen knocking or not.. .5 making the difference all depends on where you're at.. if you were at 9:1 then you may have to go 2 full AFR digits to not knock, but if you were looking at it in the aspect of "will a half a point make a difference" then there never be a reason to not keep either going richer or leaner than .5 AFR change, really you're either at the AFR you need to be or you're not, that's why we call it tunig :D ... basically it all depends on where you start and i'd say going .5 leaner might help you.. and if theres no change at all then you know it's something other than AFR to look at. PUll the timing first and then lean it out to 11:1 range and see where you're at.. you'll never know what would'veworked if you don't try some things first

On my caron e85 12:1 doesn't knock, but 11.5:1 does so
 
check your boost controller and wasgate line, it doesnt seems right for 16g to start spool around 4k rpm @WOT.

and i would turn off that antilag.....

it is fun to play around with, but you dont need if you're running 16g, and you are auto.

so turn that off, and pull down 2 degree timing starting from 5500rpm and see if that helps.
 
On my caron e85 12:1 doesn't knock, but 11.5:1 does so

I target 11.8ish under high load as that is what my car likes best. But can go quite a bit leaner with out issue

But, As well as I've seen cars that loved more timing and 11.4... It's as glen says really depended on the setup and what the car likes or makes most power on with out running into problems... .

I wish there was a way to make the AEM just the logged voltage in mode "P00" on the WB02, that way i cna convert it on a spreadsheet.. as foor boost est, not sure how to get around the user responsibility to have it calibrated correctly

EDIT if the WBo2 (AEM one) is correct i'd lean it down to abut 11:1, i've always picked up knock when as rich as 10-10.5:1

You can actually see the Raw voltage.

Hit F9 > Raw value > Then it should be listed to be displayed

Though I don't really trust the numbers depending on how they are being logged and setup 99% the time with AEM gauges the logged value as linear wideband and adjust things to match. Though it looks like it is right in the logs though... .
 
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Is BoostEst correct?

BoostEst is only useful if actual boost is being logged, and even then only at a narrow RPM range right around peak VE. (It is useful for seeing where VE peaks and starts to fall off though, if set up correctly).

With an accurate wideband being logged, I would pretty much just ignore BoostEst except maybe as an occasional sanity check, and focus on getting the wideband to line up with the targeted AFR.
 
check your boost controller and wasgate line, it doesnt seems right for 16g to start spool around 4k rpm @WOT.

and i would turn off that antilag.....

it is fun to play around with, but you dont need if you're running 16g, and you are auto.

so turn that off, and pull down 2 degree timing starting from 5500rpm and see if that helps.
Okay, first off. It's more or less a 20G. Second, if anything was wrong with my wastegate line, I would overboost (wastegate seeing less pressure due to leak or something, therefore it would open much later) and not slowly spool. Plus I have my TruBoost spring pressure set to crack at 10psi.

I start to spool before 4k, but I only have BoostEst correctly "calibrated" for 5000-5500 where VE is 100%.

Antilag has absolutely nothing to do with my issue. I know it's useless for me, I'm aware of that. But, you are right, it doesn't need to be on. I will turn it off.

Well, think about it this way, when you're right on the threshold of knock (your 2-3* is about there) a "half a point" is the difference betwen knocking or not.. .5 making the difference all depends on where you're at.. if you were at 9:1 then you may have to go 2 full AFR digits to not knock, but if you were looking at it in the aspect of "will a half a point make a difference" then there never be a reason to not keep either going richer or leaner than .5 AFR change, really you're either at the AFR you need to be or you're not, that's why we call it tunig :D ... basically it all depends on where you start and i'd say going .5 leaner might help you.. and if theres no change at all then you know it's something other than AFR to look at. PUll the timing first and then lean it out to 11:1 range and see where you're at.. you'll never know what would'veworked if you don't try some things first

On my caron e85 12:1 doesn't knock, but 11.5:1 does so
That makes sense. Especially since it could be 2-3* too far advanced as well a bit rich, I can see how I would see that knock. I'll make adjustments when I can, it's storming out today. :(

I'm going to pull 3* from 5000 on and lean it out to about 11.1:1. How lean is "too lean"? I mean if I keep seeing knock after pulling timing and leaning it out, how much more will I want to lean it out before I start assuming timing is more the issue? 11.5:1? Keep it mind, it's 91 BP octane which is unfortunately the best besides E85 in my area.

BoostEst is only useful if actual boost is being logged, and even then only at a narrow RPM range right around peak VE. (It is useful for seeing where VE peaks and starts to fall off though, if set up correctly).

With an accurate wideband being logged, I would pretty much just ignore BoostEst except maybe as an occasional sanity check, and focus on getting the wideband to line up with the targeted AFR.
I followed the link from the first post and only used MAFComp to compensate for the MAFRaw I was seeing at 5000-5500 RPM. Is that fine, or should I just put it back to stock and not mess with it? I think I wound up pulling 7.8% from the 1200 range or so.
 
it's 91 BP octane which is unfortunately the best besides E85 in my area.

You'll probably be lucky to get much above 10.8:1 even with lowered timing on 91 frog piss....at least that's been my experience.

Best performance is going to be found at a balance between timing, boost, and AFR. There isn't really a set number for any one of these; for a given AFR and amount of boost, you'll hit max timing advance for your setup. If you increase timing, you can only get so much boost, etc. The trick is finding the balance that gets the most "safe" power out of your engine.

Most people will probably recommend more boost and less timing...but that will depend on the turbo efficiency, intercooler, etc. Use what you know about your setup to get one or two of the parameters in the ball park, and then play with the other one to eliminate knock or raise power. If both AFR and timing seem high with no problems, then you can probably up the boost a couple PSI and do it again.

On 91 and your turbo, I would probably start at around 10.8:1 AFR, mild timing, and maybe 18psi of boost. Find the boost limit with conservative AFR and timing, and then work with that. Always remember to back off immediately at the first sign of knock, and lower boost or timing until it goes away. (I usually leave AFR pretty much alone, once I'm at something that seems reasonable. The best values for AFR for different fuels are pretty well known, and will work over a fairly wide range of operating conditions.)

I followed the link from the first post and only used MAFComp to compensate for the MAFRaw I was seeing at 5000-5500 RPM. Is that fine, or should I just put it back to stock and not mess with it? I think I wound up pulling 7.8% from the 1200 range or so.

Since you aren't logging a MAP sensor, you will need to use the fuel trims (closed loop) and AFR vs. AFRatioEst method (open loop) to dial in your airflow.
 
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Awesome, thanks for the help! I'll be bringing it out either tomorrow or the day after. It all depends on when it stops storming.

Either way I'll be back with results!
 
Couldn't wait. Here are the logs from about half an hour ago.

Notice how much timing I pulled.. is that normal? Will too low timing cause knock?

Also, it seems to knock every time it shifts, just at the end of the shift. I'm assuming this is just noise and not detonation?

If you notice, I keep getting tiny little blips. Those will be there sometimes, and sometimes they won't. But usually around the 5k or 6k range. Should I pull more timing?

fullgearsrun is a run from 25-100, first through some of third

strangeknock is the knock I seem to have tuned out in fullgearsrun, but once in a while my CEL (which is now set at 1*) will come on. Usually a tiny blip at 5 if it does, or right at the end of shift.
 

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10 degrees of timing for the win! Lol, just joking around. Yeah I would like to think your maf comp table is off. Check out 1992 Talon Tsi AWD Project and go from there. Your car is thinking it is running leaner then it really is and yet you are running rich so I believe it is contradicting itself, which is causing the knock when you advanced the timing to where it should be.

Look at AFRatioEst and your afr on the gauge. Its way off.

I forgot to ask, what does your boost gauge read when wot? around 5000-6000 rpm?
 
10 degrees of timing for the win! Lol, just joking around. Yeah I would like to think your maf comp table is off. Check out 1992 Talon Tsi AWD Project and go from there. Your car is thinking it is running leaner then it really is and yet you are running rich so I believe it is contradicting itself, which is causing the knock when you advanced the timing to where it should be.

Look at AFRatioEst and your afr on the gauge. Its way off.

I forgot to ask, what does your boost gauge read when wot? around 5000-6000 rpm?

Yeah, I'm so stupid sometimes. I had the preferences screwed up to display 450cc fuel flow. Now that I switched it to 650cc it's a MUCH closer but I definitely need to do some more MAFComp adjustments. I thought I would honestly never get those to match.

Boost gauge reads 15 at WOT@about 5400.

You linked me to the page I followed to begin with LOL.
:)
 
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