Mitsubishi Lancer Evolution Forums banner
1 - 20 of 22 Posts

·
Registered
Joined
·
78 Posts
Discussion Starter · #1 ·
Greetings everyone, Clayton pointed me over to this site. I did a couple of logs this morning with EvoScan and I'm still trying to decipher what I'm looking at. In the first log, it looks like I have a bit of a knock when pulling from low rpms in 2nd gear. The second log looks a little better, that was a first gear pull to 2nd gear and then lifted once I was getting close to rev limiter. Both times I was peaking at 19 psi with a taper to ~17 psi. No MBC per the SCCA rule set.

Any ideas or thoughts on the knock?
 

Attachments

·
Registered
Joined
·
86 Posts
Correct me if I'm wrong, but it looks like you're only getting max 2 counts for about 3-400rpms. That's probably also about where the car is making max torque at like 3600rpms as well so I wouldn't think from what I've researched that would be anything to worry about. It looks like the knock count is clean in the upper rpms as well. Hopefully the ones with more time tested logging can chime in here for you though.
 

·
Premium Member
Joined
·
3,496 Posts
Yeah, I analyzed it some for Russ in emails before telling him to post here and get some extra opinions. He's only seeing those low knocksums at peak torque, but you CAN see it affect timing slightly by dropping it to the 5-6* area instead of 7-8* where the map is set. On the 2nd log, he has no knock in either gear at any rpm, but you have to remember that these are low gear pulls with much less load. He needs to do some 3rd gear pulls to get a better idea of whether his car is knockprone or not. Also, boost will be higher than 19>17psi in higher gears due to the extra load, and that's what the car is tuned for...

Even so, his timing advance is great from 5000-7500, and it peaks right where it should at 19*.
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #4 ·
Thanks for the info guys. On the way home tonight I'm going to log 3rd and 4th gear on the interstate. Although 1st and 2nd gear performance is what I'm after since on an autoX course I rarely make it to third.

I have another log that is showing a lot more knock in the 3K to 4K range but what was interesting about that is the octane reading suddenly goes lower, a little bit of bad gas I think.
 

·
Premium Member
Joined
·
3,496 Posts
Hmm, I think the octane rating is an indication of the ECU trying to drop to the low octane map. It could be caused by bad gas, but it isn't saying that your octane is actually lower. It's saying that the ECU is detecting enough knock to assume your octane is not sufficient for the current state of tune/boost.
 

·
Registered
Joined
·
86 Posts
lol, bad gas :) If it continues to knock in the same rpm range in the same gear etc.. etc.. then I would think maybe pulling a bit of timing in that area or mixing in a couple of gallons of 104+ and then re-logging would be a start.
Definately post up some pulls that include 3rd and 4th gear when you get the opportunity.
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #7 ·
Ah, I understand! So the only bad gas was from the burrito last night :tease:

I was only able to pull a third gear log last night, traffic was too thick on the ride home but this is what I got.
 

Attachments

·
Registered
Joined
·
86 Posts
Looks like timing was good and no knock. I noticed though that your tps didn't hit 100 until like 4800-4900 rpm. I'm guessing traffic was the reason you didn't go ahead and drop down to about 2500 rpm in 3rd and then mash it. I'm still soaking up as much of this stuff as possible so it would be cool for me to see if nothing else. I would think at 4900rpm you were past your maximum torque threshold for that gear, which would be where cylinder pressures are the greatest correct?
Also, on a serious note about gas. Do you get it at pretty much the same spot every time? Also, I think most places where they experience winter/summer seasons have different blends for the winter months with more oxidizers and other additives, but that is just kind of an idea and may just be a crutch of an idea at that.
Looking at the log I'm guessing performance was just fine on that pull huh? :)
 

·
Registered
Joined
·
86 Posts
Thank you for that. I'm coming from the N/A V8 world and small displacement with boost changes the game in numerous aspects. Hopefully the Mustang will be sold this weekend and come spring I'll be hunting for my own 2.0L, AWD, grocery getter. :)
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #11 ·
Yep, there was no way I could drop down to 2500 safely and then go for it, I was lucky to get the pull I did! The pull was pretty good but did the 94 mph peak speed give it away? :shhh:

I'm still looking through the log from yesterday but it seems like the knock is usually in the 3K to 4K range. This what I logged yesterday, it didn't repeat later in the day though. Yes, we are running oxygenated fuels at the moment.
 

Attachments

·
Registered
Joined
·
78 Posts
Discussion Starter · #12 ·
After looking through all of my logs, other than the last log I posted, when the knocks do happen it's typically in the 2800 to 3800 range.
 

·
Premium Member
Joined
·
3,496 Posts
Yeah, that's at peak torque where timing is strong. It gives you strong torque on the boost spike, but it can occasionally cause a little knock if it's on the edge. The winter 91oct probably causes it. I don't have a problem, since I'm spraying 100% alky at peak boost.
 

·
Registered
Joined
·
86 Posts
That last log you posted also looks like you never reaced 100TPS or WOT. Maybe your timing on the 91 is a bit much with the partial, but not peak throttle. Any thoughts on this? On your other logs, even the ones that showed knock. You didn't seem to get as high of a count even when WOT. Any thoughts on this or am I interpreting the log file incorrectly? I thought under WOT the ecu uses a different look up table for timing, inj. pulse, AFR, etc... This is why I mention it.
 

·
Registered
Joined
·
86 Posts
Thank you for that. Do you know what the threshold is for this? 50% TPS, 35%...... And is that something that is also adjustable? I would assume so, but you know what assuming can do.
So russjnco sees knock counts, when he gets them, in the 2800-3800 rpm range. Hmmmm... Do you do your own tuning with anything?(Ecuflash etc..) If it's something that is effecting performance or for that matter just bothers you, maybe you could have a bit of timing pulled through that range and check some more logs.
 

·
Registered
Joined
·
78 Posts
Discussion Starter · #17 ·
I guess that's the million dollar question, is that problem or is something that's just a product of a different tune? To me it's a little bit of a concern because if the Ecu is pulling timing at that point then I'm assuming that's costing me a bit of power?

I am using Ecuflash software with a map that was provided by a vendor.
 

·
Premium Member
Joined
·
3,496 Posts
No, I don't know what the cutoff is, and I don't think there is a setting for it. With an SAFC, you can set it, but I haven't seen (or heard of) there being one in the ECU. You would think there is, but I just haven't encountered it.

We can both tune ourselves with EcuFlash, but it's not something most people play with, since it can be disastrous if done improperly. It's not as easy as picking an rpm and lowering the timing - it is based on RPM vs Load, and Load is not directly comparable to boost, although it is a function of boost. YOu have to know the proper load cell for changing timing and/or AFRs.
 

·
Premium Member
Joined
·
718 Posts
Cylinder pressures are greatest around 6k on the Evo, not around peak torque, although that can change with mods, turbos, etc. For Russ, he should be seeing peak cylinder pressure in the 6k area.
Actually, peak cylinder pressure is greatest at peak torque, not at peak HP.... that is why you ramp down the timming map as the car approaches peak torque and then ramp it back up beyond peak torque.

Peak torque = most powerful indevidual explosions in cylinder
Peak power = more explosions per second in the cylinder

Keith
 

·
Registered
Joined
·
86 Posts
Actually, peak cylinder pressure is greatest at peak torque, not at peak HP.... that is why you ramp down the timming map as the car approaches peak torque and then ramp it back up beyond peak torque.

Peak torque = most powerful indevidual explosions in cylinder
Peak power = more explosions per second in the cylinder

Keith
Thank you for that. That was my original thought, but as I stated earlier I am still trying to soak up as much of this small displacement boosted stuff as possible. It also helps me in understanding why he gets the most knock in the very rpm range where peak torque(maximum cyl. press.) is occurring with the factory turbo.
 
1 - 20 of 22 Posts
Top