ehall20

Hey all. First off, I've read all the threads I could find on here concerning partial throttle knock. I'm kind of at a road block right now, and could use any input/advice you guys can offer.

I've just finished dialing in my WOT tune, but I'm having some issues getting rid of a consistent knock at partial throttle. I get moderate-severe (can be anywhere from 1-13 knocksum) around 2500-2600 RPM and 60-100 load. I've tried making small decreases in timing, small decreases in fuel, and large decreases in timing/fuel across the board. So far, nothing has worked. I've attached my most current ROM (with timing/AFR significantly decreased in and around the problem area. I've also included a datalog (trimmed to include only cells with knock) from about an hour ago running this ROM.

The knock doesn't respond at all to decreasing timing or throwing fuel at it; I'm stumped as to what my next steps should be? From what I've seen, this seems too consistent and at too narrow of an RPM band to be written off as phantom knock, but if I'm wrong please correct me.

MechTech

Are you sure its not phantom knock? Have you logged the actual knock sensor voltage?

todd6027

iTrader: (10)

check knock sensor is tight , downpipe hitting anywhere or anything like that

ehall20

I'm not sure it's not phantom knock, but I'll give it a shot logging knock sensor voltage. I looked around the Evoscan logging parameters and couldn't find anything to log knock sensor voltage, am I missing something?

Thanks, I'll also check the knock sensor is on tight. If that was the issue or the downpipe was hitting against something, then wouldn't the sensor be picking up knock at a broad range of RPM's and not just at the one specific range of load/RPM cells?

todd6027

iTrader: (10)

No not always

ddxsamx

How is your vacuum on idle?

I ask because I pretty much finished my tune and after about a month, I am starting to get the exact same problem. (It didn't happen before) Knocking on low rpm and mine is leaning out quite a bit. on WOT it is fine (although I havent done many WOTs since it started occuring)

I'm going to be doing a boost leak test to check if I have any leaks and then checking my fuel filter/pump. I've done my injectors, coil packs, spark plugs, vacuum lines but it didn't change anything

X Double Dot

I battled partial throttle knock on my 8 for 2 years. I tried the timing and fuel changes, new knock sensor, checked everything for leaks/rubbing....all without it helping.

The two things i did that I had the most confidence in were, try a 100-110 octane fuel, if it still knocks, it's likely false (at part throttle). The final thing I did to confirm it was fake was make a set of det cans, I used this kind http://www.d-series.org/forums/diy-f...5-dollars.html and drive around listening/comparing to the logs. Once I was finally finished with that I detuned the sensor following instructions on this forum. Plan now is to monitor spark plugs at oil changes to confirm.

Best of luck.

ehall20

Thanks for all the input all. According to the OEM boost gauge, vacuum sits around 50 cm/hg at idle. Evo X MAP sensor shows the vacuum hovering between -7 and -9 PSI at idle. I tried logging knock voltage, knock ADC, and knock base with Evoscan; but I'm still trying to figure out how to convert the data into useful information to diagnose my issue.

There's a station with 100 Octane nearby; once my tank is a little more empty I'll fill up there and report back if the knock clears up.

german_evoVII

You are still running the EGR System?

If not ( Plate installed instead of the vacuum actuated Valve ) you will also have to disable the EGR Timing table by zeroing out.

If not, then you will see an Ignition advance up to 7 degrees in the load areas 60 to 100 and 2000 up to 4000 RPM.
Since no Exhaust gases coming to the intake, the fuel burns faster and will get into knock.

Also, an clogged EGR Valve will have the same effect......
Also, an poped OfF val line there will be making these troubles....
EGR Valve is sitting right below the Throttle Blade, below the ISC Servo.

crthomas1952

There are two boxes you can check pretty far down the list in EvoScan. One is knock base, the other is knock adc. Then, download Merlin's guide here:
http://www.evoscan.com/technical-veh...le-efi-systems
and read about false knock. I think this is what he was referring to.

merlin.oz

german_evoVII posts #9 back a bit is the most common cause, but do the 100 octane test first.

But, if you have done lots of mods to the Evo (read any evo) getting rid of EGR is a good idea, as its effects become progressively more intrusive.

ehall20

Just put a few gallons of 100 octane in the tank. There was still some 92 left over, so the mixture is approximately 20% 92 octane, 80% 100 octane. About 15 miles after filling up, I'm still getting knock at the same RPM range.

I'm still running the EGR system for now, but I plan on doing some research and finding out what the benefits are of removing it.

LightningTuned

Same problem here. Bought my 03 8 2 months ago, came from DSMS so i know how to use ecuflash and tune. figured it owuld be no problem. been chasing phantom knock for 1000 miles. always in 2500-3500 range, sometimes i get it, sometimes I dont. Let me know if you find anything out.

memphis69

iTrader: (9)

same s**t. what mileage? if it's 50k+, change lifters to new OEM.

X Double Dot

70k. Did this fix your issue? I've had mine out and cleaned them, but yea no idea if they are as good as new ones still