Opinions on my knock problem

[Lgarretto]

Hey guys
I'm just looking for an opinion or two. Not necessarily to ease my mind, maybe to kick myself if something breaks. But I have been tuning on e85 via datalogs for about a month with pdb, and I want to say they have been great. Great customer service and very friendly I have no issues.
I am getting some knock. I was getting about positive 6-7 knock with 91 and get about the same on e85. I found a spot where my mgw shifter strut is very close to the trans tunnel, it was touching at first, and tried to move my engine and trans over but it's already over all the way. I stuck a pry bar in there and bent out the tunnel a bit where it's close. No biggie. But it's still close. I think that's where my knock is coming from. I did also get a revision with about a degree of timing pulled (about 25 to 24) which lowered my knock to about a positive 1. I know my fuel is good and my plugs were brand new oem replacement when I switched fuel. I'm just curious if anyone had any input or anything on the matter.

Oh, the knock isnt constant. It stays at negative 6-5 until I Rev over about 3500 or so. Then spikes either 3500-6000 on wot or whenever I shift if I shift hard and early

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[thelostotter]

Doesn't it point to the tune being the issue if reducing spark advance reduces how much knock you log? I would think false knock would stay relatively constant if timing was reduced.

 

[Lgarretto]

I don't know. This is the first car I've tuned that didn't have a carb.
We tried reducing timing a little more but it made it worse.

 

[Lgarretto]

I asked if he can maybe up the fuel. I don't know how to read the fuel trim part. I don't think it shows it.

 

[The Demon]

Doesn't it point to the tune being the issue if reducing spark advance reduces how much knock you log? I would think false knock would stay relatively constant if timing was reduced.

^^^ I am by far no expert on knock or tunes but if you’re getting it on E85 that tells me that the tune is wrong.

 

[Lgarretto]

Yeah. Everything points to that or to false knock. And I can't see a lot of false knock at this point

 

[AZ18yote]

^^^ I am by far no expert on knock or tunes but if you’re getting it on E85 that tells me that the tune is wrong.

Unless maybe it's low quality e, like not true e85 and it's actually flex fuel with e54 but the tune is not flex and is expecting straight e? OP what did your e test out to? Or you got some rubbing / vibrating/ bouncing triggering knock?

 

[Lgarretto]

I tested my fuel at 85 once and 86 again the next week. Here in Oklahoma good fuel isn't much of an issue
I also replaced my spark plugs with OEM Ford Motorcraft plugs whenever I switched to E about 3 weeks ago.
Pbd says he thinks it's a slipping clutch. The clutch is probably original. And the car has 60k miles. But replacing tgr clutch isn't an option for me yet. And it feels fine.

 

[givemeadollar]

I tested my fuel at 85 once and 86 again the next week. Here in Oklahoma good fuel isn't much of an issue
I also replaced my spark plugs with OEM Ford Motorcraft plugs whenever I switched to E about 3 weeks ago.
Pbd says he thinks it's a slipping clutch. The clutch is probably original. And the car has 60k miles. But replacing tgr clutch isn't an option for me yet. And it feels fine.

Why are you using oem plugs? you should be on NGK 6510s or similar.

 

[Lgarretto]

A hotter plug? I bought oem ones because most of the other you can get are colder unless you order them. But maybe I need a hotter plug

 

[NGOT8R]

I run NGK 6510s in my E85 tuned car, but the main reason for the colder plug was setting the car up for nitrous. It does run fine NA with these plugs though.

OP, do you have LTHs? Have you checked to make sure your mid-pipe isn’t hitting the floorboard or that the primaries aren’t hitting the frame rails during engine torque-over? If so, polyurethane motor mounts can eliminate the torque-over and help prevent false knock.

 

[LunarS550]

I was having false knock issues on e85 at one point, ended up needing new spark plugs. Threw new stock ones in and never had an issue from then on. (Was tuned by PBD) Sounds like it's most likely not your issue however.

Why are you using oem plugs? you should be on NGK 6510s or similar.

I ran stock plugs while I was FBO E85 and didn't have any issues, ran great. I'm no expert but 6510's are more recommended for boosted applications.
I just switched to 6510's when I installed my procharger.

 

[Lgarretto]

No. No headers at all. Magnaflow cat back. I've shook it all around and it doesn't seem to hit. The closest thing was the bolt on the shifter strut. Which is still close but there's nothing I can do now. When I bent the trans tunnel out for it my knock went down from 6 to about 4. Then I got a revision with less timing which dropped from the 4 to about 1-2. Tried another degree of retardation for the timing, knock went back up. To about 5 I believe. I'm back to the previous revision now. Logged yesterday with a max of 0 on a 3rd gear redline pull and a max of 2.0 when getting on and off the throttle just spiritedly running through some gears

 

[slime_bullet]

Checked your motor mounts? E Brake cable? Exhaust flexing under load between cats and axle back? Try and check exhaust while it's still warm.

 

[Lgarretto]

I'll check my exhaust again. I tried moving it as much as I could under the car. And I did check the e brake cable. I saw that was a common spot. But that looks good. I'll check all that again.
I guess what I am more trying to decide is whether the general concensus would be that it's probably false or not. I don't wanna turn down the sensitivity of the sensor if it isn't of course. But I've checked things for touching several times. At a certain point, and at only positive 1 knock, seems to me if it's false lowering the sensitivity 5-10 percent may not be all that bad

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