How do I deal with knock - datalogs showing masive knock

[Kornilov]

I just recently got my SCT X4 in anticipation of getting an AED tune. My first datalogs showed some massive knock from 4-5K rpm at WOT in 3rd gear (up to 5+). Shaun says he wont tune the car until the knock is resolved. My first approach was to put the car on a lift and go over exhuast components to ensure no looseness. Everything is on tight and proper: axleback connection, OAPs, H-pipe clamps. I zip tied some cable and lines out of the way on the bottom of the car and there was a vacuum tube in the engine bay that had worked its way out of its holder that I re-adjusted. However, everything else that is obviously apparent looks properly secured.

The car is a stock 2011GT with MAC axlebacks. I almost universally run Shell 93. Previous owner did extensive mods but I bought the car with 2200 miles on the odometer after he had returned everything to stock - done to the paper filter in the airbox.

Just tooling around today, I ran a super long datalog with some partial WOT pulls to see if there was any difference. There is still knock being recorded.

So my next approach is to run the remaining tank of gas down and try another station and brand. But if this isnt a gas issue, what other things can I look at to address the knock?

I will try to empty the tank tonight and get some fresh gas to get some datalogs tomorrow. Shaun didnt provide any guidance aside from "fix the knock and then come back with more datalogs".

 

[4VFTW]

put some race gas/torco in it and see if the knock is octane related

 

[Kornilov]

put some race gas/torco in it and see if the knock is octane related

Looks like there is a Sunoco not too far away with some 'race fuel'. Not sure what octane it is, but will drive out there tonight and fill up. If I can confirm that octane isnt the issue and Im reasonably sure no loose components are causing false knock, what other culprits can there be? I've never noticed any issues with the motor - she runs well and pulls hard.

 

[Blazer707@TBR]

More then likely it will be fuel related.

 

[BrianH87]

Are you sure you are running the stock tune and not one that the previous owner left on?

 

[ERS]

Does you car have an oil separator installed? If not, oil introduced into the intake from the PCV has the potential to reduce your fuel's octane rating, causing knock. If you do have an oil separator, ensure the fittings are sealed and tight, if there's a vacuum leak, it would cause a lean condition and also causing knock. Ive heard of Shaun being able to detect this, either on a data log or on the dyno before.

 

[Kornilov]

Are you sure you are running the stock tune and not one that the previous owner left on?

No. Im not certain. How would I be able to tell if he left the tune in place? I know the car WAS tuned, but I was under the impression that the stock tune was on the car. Ive had a number of trips to the dealer for warranty work and no one has informed me that the car is not running on the stock tune. Like I said, I sent my logs to Shaun, so Im not sure if he can tell if he's looking at a stock tune or not, but he didnt say anything about it either and I told him as far as I knew it was running the stock tune.

 

[Kornilov]

Does you car have an oil separator installed? If not, oil introduced into the intake from the PCV has the potential to reduce your fuel's octane rating, causing knock. If you do have an oil separator, ensure the fittings are sealed and tight, if there's a vacuum leak, it would cause a lean condition and also causing knock. Ive heard of Shaun being able to detect this, either on a data log or on the dyno before.

JLT passenger side oil separator was the very first mod I did to the car. I just looked over the motor yesterday and the fittings were secure. Unfortunately, Shaun must've been super busy last week, because he gave me exactly zero to go on aside from (and Im paraphrasing) "there's knock, I wont tune it, get it fixed, Im not ruling out any causes." My last email to has gone unanswered.

 

[NOWARRANTY]

Post your logs and lets see what we can see. Knock, Lambse Bank 1/2 & Spark to start with. Is the car running lean during the WOT runs?

 

[50blackout]

When I had my car tuned by Shaun it had a little bit of knock at 5k rpm. He wouldn't tune it, until the knock was gone either. Basically it ended up being carbon deposits for me, and to get rid of it, I had the car run at a high rpm for an extended period of time (not sure if it was WOT or part throttle) to "melt" the carbon deposits off. This worked, so try this method (Race gas + plus HIGH RPM use) and see if the knock gets better. 5 degrees is a lot of timing being pulled, so I understand why he won't tune your car. If this doesn't work maybe its some sort of "false" knock"

Also DEFINATELY make sure you have the stock tune. You could have an aftermarket tune that's running very high timing. Good luck, Knock is a mother fing b@#$%

 

[BlueSmokem5.0]

Knock is such a pain in the ass. I have been struggling to find false knock on my car recently. I put it on a lift went over everything with a fine tooth comb and found nothing solid to convince me that was the problem. But I've been trying to dial in my new 150 and 200 shot tunes and on the street when I log everything looks perfect no knock at all. Then I went wed night and every pass showed knock off the line that tapered off through the run very slowly back to zero. Running VP101 so I know that its not from poor fuel but I think it might be a busted or bottoming out rear differential bushing in the top of the housing only stock suspension part left in the car.

 

[Kornilov]

Post your logs and lets see what we can see. Knock, Lambse Bank 1/2 & Spark to start with. Is the car running lean during the WOT runs?

Really, aside from rpm and knock I dont know how to interpret the logs, but here are my originals that I sent to Shaun, log 1: 2k-redline 3rd gear WOT:

log 2: 1.1k-5k 3rd gear slow, steady throttle:

 

[BrianH87]

Not that it matters, but you should use the short and long term fuel trims PID not SAE. Never use SAE.

 

[Kornilov]

Not that it matters, but you should use the short and long term fuel trims PID not SAE. Never use SAE.

Right. Will re-do the configuration.

 

[NOWARRANTY]

Lambse Bank 2 readings look a bit scary (ie..lean) IMO on the WOT pull. Even on the easy going 1-5K pull the same Lambse Bank 2 readings seem out of wack. Not sure how to nail down the culprit but I would take it to the dealer and see if they have a way to test the injectors...etc to see if they are operating correctly.

 

[Justin81]

I'm having a BS Knock Problem myself. My tune was spot on in the spring. I pull the tuner back out to check it last week and it is putting up 1.5 to 5* of KR. However, here's the catch. It only happens for a very brief second right at acceleration. I backed up the driveway and it recorded 5.6* in 1 second. The car has zero KR at WOT and all parameters otherwise are spot on.

After some research, It looks like I may be dealing with something called Burst Knock. I understand it's when the rate of timing is increased at a very fast rate and the computer tries to correct it immediately.

 

[Kornilov]

Here's another 3rd gear WOT pull (up to 6k rpm). This is with a new Mobil 93 gas. Im waiting on my little Ford funnel to come in so I can run some Sunoco 104 to see if I can alleviate gas as cause of the knock. My knock comes on initially just above 4K rpm and peaks right at 5K. Multiple logs look similar. Although the colder the motor is, the less knock it records.

 

[JerryC]

they sell those little funnels at Autozone.

 

[Kornilov]

they sell those little funnels at Autozone.

The ford specific ones? Do you have a part# or description? I bought one of the Ford ones on eBat for $7 shipped, but it wont get here till later in the week.

 

[JerryC]

Not Ford specific funnels, they work in lots of vehicles. Just ask for the little funnel for new car gas tanks. My AZ likes to hide them in places you would not expect