Knock Sensor Activity

[gqneon]

I've noticed that my car with a CAI and Bama tune and then subsequently with a D1SC ProCharger build up both seemed to want to take less timing than most GT's. I don't EVER hear any audible knock, and believe me I listen. I keep thinking it's got to be one of 3 things:

1. An engine/vibration issue.
2. A sensor issue.
3. A fuel issue.

Lund is tuning my car now, and also noted it's not taking but 14-15 degrees towards the top whereas most 15's he's tuned with similar builds can take 17-18 without issue. I put it on the dyno today and logged my first pull and sent the log to Jon to look through, and I'm curious to see what he thinks. The HP / torque numbers aren't where I was hoping, but I think it's directly related to 1, 2, or 3 above. Lund is apparently the wizard of Ford Tuning, so I'm doing everything he says when he says to do it and I trust his word and work.

I buy my gas at QuickTrip (QT) - 93 octane. There's parts in my curve down low and towards the middle where it's taking 18-20 degrees, but up high it can get as low as 14, which is just a huge power robber. I'm just trying to think through what could be a cause of "false knock" to eliminate. I'm wishing I had my stock exhaust to bolt back up to the car and see, but my car was delivered with the Ford Motorsports exhaust and I can't help but think the raspiness towards middle-high rpm might be tossing enough vibration to F with the knock sensors.

I don't think it's the fuel, and I don't THINK there's anything wrong with the sensors. I took out my Whiteline trans insert thinking it could be causing vibration and no difference. What else can I look at to whittle down my possibles?

What am I missing?

 

[Weather Man]

Add a can of torco and see if the knock goes away. If it does, you know it is fuel related.

 

[gqneon]

A guy mentioned Torco to me today with a GT500 he had at the dyno shop. Says he runs a half-can per tank for his car. He also told me he clogged up one of his 3" cats on the Texas Mile this year and had to gut them, but I have no idea if that's got anything to do with Torco.

**EDITED**
Edit : I stopped being tired and lazy and googled it and answered the question I posted (below.) It's been a long day. Thanks for the suggestion - I'm a little miffed that the dyno shop didn't suggest it since now that I've seen it on their website, I recognized that they sell it in their shop I was dyno'ing at.

And the advancetrak error came up on the dyno - but we didn't know how to clear it other than to drive it about 25 feet, but he wasn't about to do that and strap it back down, so I only got 2 of the runs I paid for and one of them was junk from the advancetrak deal (less than stock power).

Scotch + sleep coming my way. Tomorrow's a new adventure.

Original :

It's not like a lead additive or anything I'm assuming?

 

[Budwise]

From my experience some Texas gas just sucks but at least you're coming into the summer blend which is much better than the winter blend. My 13GT I never could figure out the timing issues with it even with Torco. Shaun at AED thought I may have damaged something internally running HPDE's so I traded her in pretty quick lol. Needless to say on my 15 I got the extended warranty and will not be tuning because its just too much headache. Coilovers and other mods will come though.

 

[SID297]

QT typically has decent gas in this area, but different additive packages have been known to cause false knock. Rather than use Torco I would buy a couple of cans of Gulf racing fuel.

 

[gqneon]

I'll see if there's a way I can find some locally. Wish we had pump 100 closer than 50 miles away, I blow a quarter of it on the way home even if I fill up. Assuming it's a quality 100 octane. I still don't know exactly where this mystical 100 octane pump is, but apparently somewhere off 75.

 

[gqneon]

So I dissected my first dyno log and saw it dropped to 12.5 degrees. Not good. I ran it almost dry and filled it up with 100 octane race fuel from Mobil. Took it back to the same dyno, turned of traction control and did 1 pull for comparison. It measured ZERO knock under boost and ran between 17-18 and it looks like the command graph was steering it back to about 16.5 at 7200. So fuel may be the issue. Anyway, feel free to post here or there. I bought a can of torco too just to see, but haven't tried it yet. Might save it for trying different local gas stations blends and adding it in case they don't measure up lol.

I'm linking a post with some dyno graphs to give some context to this post.

http://www.svtperformance.com/forums/showthread.php?1075163-Some-success-in-progress&highlight=

 

[gqneon]

I'm going to put together an oil catch can and plumb it inline with my intake tonight or tomorrow. I'm guessing of oil vapor COULD be an octane reducing factor, I will go ahead and eliminate it as best I can. It sure can't hurt, I hope.

 

[gqneon]

Weirdest thing. This afternoon, since I was putting in my stainless clutch line, I went about hacking up my JLT oil catch can and with new hose and fittings plumbed a custom PCV route for my D1SC setup. Instead of using the two PCV inlets to the intake tube like the instructions (like I had) I ran the PCV from the passenger side behind the engine to the driver side PCV. Just before the driver side PCV, I put a 5/8" tee and dropped it down towards the strut tower, where I tied in the 3/8" vacuum line from the y splitter behind the engine. I then ran the single 5/8" PCV line from there to the oil catch can (with new 5/8" barbs on both sides) as a single inlet to the intake tube fitting before the blower inlet.

I just figured if it worked it would reduce the amount of oil making it to my intake tract and maybe reducing the potential for lowered octane effects.

What I found was that it smoothed out about 90% of the surging I was experiencing at the 0-5 inch of vaccum mark mid throttle. It's not totally gone, but it was SO MUCH better and smoother. I stopped and checked it and told myself it was all in my head. So I took it back out later with my wife and she said the same thing. I checked all the fittings, and again, everything was tight.

Not what I was shooting for, but hell I'll take it. That's a hell of a bonus for getting the oil catch can back in my loop. Now, rather than surge, surge surge surge surge at mid throttle, if it finds that spot, it's just for a second and it's gone.

Just thought I'd share that around in case anyone was thinking of doing anything similar. I just hated that ProCharger had me putting a rubber hose onto my PCV valves. It was killing me. So instead of cutting up the original parts, I bought hose, elbows, and tees and used Ford PCV clips. Worth every minute, and much cleaner too.

 

[gqneon]