Hi evo friends! I've been having some odd issues with some low RPM and low load knock and I was hoping to get some input from the tuning community.

QUICK background information: Car is a 2003 evo 8 running FIC 850 cc injectors, wally 255, 3" TBE, open air filter, mbc (like 24 psi), stock turbo, stock motor. Ecu Flash / Evo Scan. Getting AFR through AEM W/B gauge.

I did some mild tuning to get it set up for the 850's, pulls decent, got it in the 12's last year with two sets of bent valves. Just got the car back on the road after an issue with my radiator leaking. I've run into this scenario before, but saw it again on my way to work. I get a bunch of knock at low RPM (like 2500-3000) when I go almost WOT. I'm not sure what's wrong or what to look for. I'm new to ecu flash, but I've used DSMLink of my other DSMs with pretty good results.

I've attached the current tune's bin file as well as a log from this morning. Specifically look at rows 9841 to 9857 (entry time of 47:12, to 47:14 roughly). Please let me know if I can provide any further information to help.

Thank you!

 

looks like youre experiencing some phantom knock, have a check around make sure nothing is rattling like heat shields etc

 

The only heat shield left on the car is the one over the exhaust manifold. I suppose I could try removing it. Otherwise the car gets a decent amount of vibration from the whiteline rear diff bushings.

 

I copied the stock ignition map from the latest tephramod v7 download over to my current tune and changed nothing else. I took it for a 30+ mile drive to work this morning, and much to my dismay I am still seeing major knock while building boost. I will provide as much information as I possibly can, but I would really appreciate someone taking the time to look this over and help me out. I've included both the raw log (.csv), and a formatted log file (.xlsx) that highlights the knock and a fuel cut issue I saw as well. If it's easier, here is a link to my logs on my Google Drive as well. Look at the logs with a date of 4/11 -Evo Logs

First, the knock issue. I think there are three instances in this log file (all highlighted in the Excel file). Knock count goes up into the high 20's...something is definitely wrong. The only thing I can notice here is that knock appears to start where the o2FeedbackTrim goes to 0. I assume this means it goes into WOT mode, right? AFR is rich, so I don't think that's causing knock. In the first knock instance, AFR starts around 13.9 and dips to 10.8 at the lowest. This is being logged from my AEM W/B. In the second knock instance, AFR dips down to 10.1 at the lowest. With all three instances, o2FeedbackTrim is 0 when the knock starts...I am not sure what this correlation means.

The other thing I noticed, and not sure how relevant it is, but the coolant temp stays under 200 for most of the trip, its over 40 minutes in to the drive where the temp pops up to 203. I just replaced my leaking Mishimoto radiator with a new one. I burped it the best I could, otherwise I don't know what would cause this.

Other things to mention about the car that might be relevant. Stock turbo, 850 FIC injectors, 255 wally, mbc, 18psi wga, 3" exhaust, no A/C, no emissions equipment, evo 9 bov, Mishimoto FMIC, hard LICP, stock UICP.

Now the last thing I noticed that was strange this morning was I got a decent 2nd gear pull, or started to, and seemed to hit fuel cut?! You can see in the Excel log, the last set of highlighted rows, on line 16032 injector pulse width and duty cycle hit 0. Not sure what's happening here.

Any help is GREATLY appreciated guys. I've been helped by good guys on the forum in the past and I'm hoping it can happen again!

 

Try reflashing to any other completely different rom, even better to flash a rom with different ID and then reflash back your tuned rom. That helped me to get rid of phantom knock completely on a few cars.

Also instant knocksum of 36 mean your knocksensor may be faulty, or any of its wires is broken. That makes your car instantly lower "octane" parameter to 0 and fully switch to the low octane maps. That cause super rich AFR and super low timing numbers.

Make sure your knock sensor wiring is fine and the sensor itself is torqued to specs without any additional grommets, washers gaskets etc... I've seen a few cars where I could unscrew the sensor with my bare hands.

As for AFR - there IS such thing as knock induced by overly rich AFRs. Better stay in mid 11 as the richest point at full load.

 

I can certainly check on the knock sensor, and that would be a super easy fix if its just loose. However, I don't understand why it wouldn't read anything on other pulls? Is there a way to test the knock sensor? I know new ones are not cheap.

 

Try logging knock voltage.

 

Perfect. I can log this on the way home. Anything in particular I should look for?

 

Any unusual spikes or dips in problem areas of the map.

 

You Fuel map looks stock-ish and AFRs appears to be too rich at mid and full load. Also your low load AFRs are too lean and trims are always positive, trying to add fuel to compensate wrong scaling\latency at cruise conditions. Ignition timing map looks too agressive in 150+ load area. All this doesnt look like a tuned rom to me.

 

Fuel and Ignition maps should be stock, or damn close to it. The only changes here are the adjustments for the 850 injectors and some misc bits to prevent CEL from coming on for missing emissions equipment. This should also have my launch control stuff in there too.

 

Then it would be wise to turn the boost down until you figure out your knock problems and fully tune your car.

24psi is asking for trouble in your case...

 

Yes, good idea. I logged again and got more knock data, but nothing looks out of the ordinary. It appears the knock sensor is working as intended, but is picking up another vibration that it thinks is knock. Or at least that's my theory. I think a combination of very worn motor mounts combined with stiff bushings in the rear end plus big 3" downpipe that's very close to the chassis support bars undearneath are causing vibration as the motor twists and moves as boost comes on. That's just a theory, but I was planning on doing motor mounts anyway.

In either case, attached is a copy of the log from today.

 

have you checked your knocksensor? have you tried re flashing rom as I adviced?

 

I haven't tried with different roms yet, but I definitely will this week. Thank you!