Real Knock Vs False Knock

[TheRedBeardedFury]

How do you determine real knock vs false knock? A little back story on why the question. I got my sho about 2 months ago and been slowly working on its issues. It came with a 5 Star 93 tune. Everything was good for first 2 weeks and then I ran into some transmission issues. I was getting pretty bad flare shifts and a little slip but no torque converter shutter that I could tell. Following SM105k's Sho bible, thank you SM105k I'm sure this has been a lifesaver for a lot of people! I figured it was the perfect time to start the maintenance schedule. First 5 in and 5 out transmission fluid was super rough. I thought I had pulled the oil plug somehow lol. First drain and fill there was a noticeable change for the better. Drove it around for a few weeks and did another drain and fill with adding a bottle of **** guard this time and boy what change. It has been way better now for a few weeks. Now I have noticed strong positive knock from the sensor only on wot pulls. At light throttle or daily driving with the tune I almost always have -5 KR. Even with this issue going on I still see the -5 KR. It seems anything more than 3/4 throttle is when I start seeing positive knock. I've listened to the engine at idle and everything sounds fine. When seeing the positive knock, I'm not hearing anything abnormal from the engine. Im on my second tank of 93 from a different station with no change. Over the weekend I loaded stock tune to see if knock would go away. With the stock tune I still got the positive knock at wot but much less. With 5 star is been +4 to +7 and with the stock tune highest I saw was +3. The only things that have changed are the transmission drain and fills and added a upr dual side catch can about 500 miles ago. Ive been all over the forums and pages trying to research this and mostly what I see is people with knock under light throttle or lugging. The very few I have seen about knock at wot where saying its very bad. I'm worried about it and almost dont want to drive it in fear im going to hurt the motor if its not already hurt. Only things done to it are 3rd cat and resonators deleted, Colder plugs, 170 t stat, UPR catch can, and five star tune. I do have a data log with the five star tune showing the knock but not sure I have all the right pids to determine anything or if that's even possible by looking at the log.

 

[Sleeper.Solutions86]

There’s a difference between the PIDs KR and knock correction. You should be watching knock correction. That’s how much timing is actually being pulled.


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[TheRedBeardedFury]

The pid Im monitoring just says knock. When at -5 spark advance V2 will be in the 30-40s and when seeing positive it'll be as low as 10 degrees. When on the 5 star tune the oar will also jump to -.75 from -96 but doesn't take long to go back after the pull. On stock tune oar didnt move.

 

[Sleeper.Solutions86]

You should be able to find a pid for knock correction on SCT. I know for a fact HP tuners has it because that’s what I watch. You’d see KR GO TO -7/-5 but the actual knock correction is 0.3*-0.7* but it’s only for a split second and that’s normal. (I tuned my own car.) the only time I saw it go as high as you’re talking about on just 93 when watching KR not knock correction was when I had a micro crack in one of my spark plugs.




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[SM105K]

Sounds like crappy winter blend fuel. Do you have E85 in your area? If you do, I would put about 3 gallons with full fuel fill up and see if the knock goes away. If it doesn't then you can start looking for the other reasons.

 

[TheRedBeardedFury]

Sounds like crappy winter blend fuel. Do you have E85 in your area? If you do, I would put about 3 gallons with full fuel fill up and see if the knock goes away. If it doesn't then you can start looking for the other reasons.

Am I able to do that with a 5 star 93 performance tune or do I need to wait and get Matt's tune before I can try some e in a tank?

 

[2K16SHO]

Am I able to do that with a 5 star 93 performance tune or do I need to wait and get Matt's tune before I can try some e in a tank?

Yes, you can run 2 to 3 gallons of E85 with your 93 tune.

 

[SM105K]

Am I able to do that with a 5 star 93 performance tune or do I need to wait and get Matt's tune before I can try some e in a tank?

I personally would take the 5 star tune out ASAP. They might be good in the F150 world, but they aren't a major player in the SHO world. However you will be fine putting a couple of gallons of e85 in. We just want to bump the octane up to see if that will stop the knock.

 

[TheRedBeardedFury]

I personally would take the 5 star tune out ASAP. They might be good in the F150 world, but they aren't a major player in the SHO world. However you will be fine putting a couple of gallons of e85 in. We just want to bump the octane up to see if that will stop the knock.

Yeah I think I agree. Can't find anything on any shos with 5 star tunes and one thing concerning is it has the factory map and pushing 15+ of boost. I've kept it on the stock for now since I see less knock activity too. Went ahead and bought a tune from Matt just waiting on it to come in now. I'll try the e when the tune comes in and baby it till then. Really hope it's as simple as bad gas and not a real problem.

 

[SnuffyTheSeal]

Definitely credit to what SM105 said. My SHO has been gas picky ever since I bought it (Marathon in particular seems to run poorly in it) and I've heard others say these cars want at least mid grade when not tuned. Definitely put a little E85 in if possible. If you can't get it easily most part stores have an octane booster product you can get too.

 

[ShatteredMJ]

Here’s one thing I figured out the hard way with lots of trials and errors. The UPR WOT line will pull oil mist to the intake with hard pulls and over time and repeated pulls oil would condense in intercooler and charge pipe. Especially if the can has collected a good amount. This happens with upgraded turbos or high boost levels in tuned cars. After it collects for a while, it will contaminate your charged air under boost and cause knock.

Easiest check is to remove your intercooler to throttle body pipe and check the couplers especially at the intercooler outlet. My temporary fix was to disconnect the UPR WOT line from the intake and make it function as a one-way VTA valve under boost since it cracks open at 0 psi (upgraded checkvalve option) and within a few days/pulls this issue resolved. My permanent fix was switching to a hybrid UPR catch can with a one way breather.

I’m not saying this is your issue as my setup is totally different but it’s worth checking. I believe the UPR design for our car is made for stock vehicles and not tested at ~20 PSI of boost.

A few other things that might cause this other than obvious fuel octane issues are loose or rattling mounts or downpipes touching on metal. I even had a dropped 10 mm socket once cause irrational knock readings until I fished it out with a magnet.

 

[Sleeper.Solutions86]

Here’s one thing I figured out the hard way with lots of trials and errors. The UPR WOT line will pull oil mist to the intake with hard pulls and over time and repeated pulls oil would condense in intercooler and charge pipe. Especially if the can has collected a good amount. This happens with upgraded turbos or high boost levels in tuned cars. After it collects for a while, it will contaminate your charged air under boost and cause knock.

Easiest check is to remove your intercooler to throttle body pipe and check the couplers especially at the intercooler outlet. My temporary fix was to disconnect the UPR WOT line from the intake and make it function as a one-way VTA valve under boost since it cracks open at 0 psi (upgraded checkvalve option) and within a few days/pulls this issue resolved. My permanent fix was switching to a hybrid UPR catch can with a one way breather.

I’m not saying this is your issue as my setup is totally different but it’s worth checking. I believe the UPR design for our car is made for stock vehicles and not tested at ~20 PSI of boost.

A few other things that might cause this other than obvious fuel octane issues are loose or rattling mounts or downpipes touching on metal. I even had a dropped 10 mm socket once cause irrational knock readings until I fished it out with a magnet.

I’ve only seen this happen when the catch can lines are installed with the check valves facing the wrong direction. The arrows must be pointed AWAY from the catch can.


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[TheRedBeardedFury]

Yeah I still have the stock stuff I could try putting back on after I check the check valve flow but I'm pretty sure they are both pointed away. I also believe there's quite a few people that ran them after being modified without any issues like SM105K. I believe Jordan also ran one on both of his setups without issue. I'm not getting a lot of residue in the catch can either. Maybe 2 tablespoons after about 500 miles.

 

[ShatteredMJ]

I’ve only seen this happen when the catch can lines are installed with the check valves facing the wrong direction. The arrows must be pointed AWAY from the catch can.


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This issue may have been unique to my situation. True. When correctly installed, the WOT line is using intake vacuum to keep the dirty side PCV valve open when boost in the manifold shuts the inline check valve. It basically takes over the job of the manifold vacuum. The UPR pro check valve cracks open at 0 PSI.

In my case I have upgraded turbos, EPP dual intake and a final drive ratio of 3.65 which makes highway driving/cruising stay at higher RPMs and generate a ton of airflow (like you’re spooling turbos) to the point the stock BOVs open and whistle while cruising. At higher highway speeds I’m convinced that the WOT check valve was cracking somehow while manifold is still in vacuum and kept dumping whatever it sucked out into the intake tract. After fixing it the catch can started collecting properly. It used to stay almost empty with minimal to no collection all the time.

 

[TheRedBeardedFury]

A little update. I loaded matts tune on the car this morning. Boy what a difference compared to the 5-star tune. Like night and day. Every complaint I've had about the 5-star tune doesn't exist with matts. Cars a ton more responsive down low and doesn't want to lug like with the 5-star tune anymore thank god. That was the biggest thing I hated with the 5 star tune. Especially with hills. It pulls a lot harder too. I see why everyone talks about shifting with his tune also. Its so much better. Now the knock. The knock was still there as expected but much less then with the 5-star tune. With matts tune knock looks to be the same as with the stock tune. I have not yet tried adding some e to see if its gas related yet. I sent a log of to matt and awaiting his response. I did verify that the check values were facing the right way with the upr catch can. Was a long day today. Woke to a flat so had to take care of that. Then when I went to flash the tune and the bms was shutting the car down as soon as it was going into key on mode, so I had to go back out and get a battery. All in all very pleased with matts tune.

 

[SM105K]

Good good. See what he says. Most likely he will say throw some E in the car to rule out mech issues.

 

[TheRedBeardedFury]

Okay in prep for winter storm coming, I needed to fill up. I went ahead and added 2 gallons of e85 and rest 93. Car seems to really like it. Knock is much happier. I did about 10 pulls and with 8 of the pulls knock was negative to 0 with a split second of .5. The other 2 pulls were the same with a split second of a max knock of 2.75. Given this info are we still suspecting trash 93/winter blend was the issue? If so, what is the long-term solution?

 

[SM105K]

Okay in prep for winter storm coming, I needed to fill up. I went ahead and added 2 gallons of e85 and rest 93. Car seems to really like it. Knock is much happier. I did about 10 pulls and with 8 of the pulls knock was negative to 0 with a split second of .5. The other 2 pulls were the same with a split second of a max knock of 2.75. Given this info are we still suspecting trash 93/winter blend was the issue? If so, what is the long-term solution

I would venture to say that the winter blend 93 is trash. Get fuel from another station. I only run Shell or Chevron in my boosted vehicles.