Want more power but can't with tuning...

[91hybrid]

So I took my new 14 SHO PP to the track last week with her fresh tune and 2700 miles on the odometer. Ran well but was down from where I thought the mph should be. She ran pretty consistent with a 1.87 60' crossing the trap with a 13.32@101.5. My 14 with a tune only trapped 1mph faster than my '11 non PP did (0.45 sec faster due to the 60 foot though...). I started wondering where my other 4mph was so I data logged the car and found that I was maxing out my knock sensors at 7.5 deg's pulled, resulting in a whopping 7 degrees total at WOT.  Talked to my tuner and he pulled timing out of the motor and I re ran it. It still pulled timing out but now only 6.25 deg (0.25 deg total). So I started thinking the knock sensors were lieing to me so we added the timing back in and slowed the knock sensor responce time. This resulted in audible knock (not to me but my wife...her hearing is much better than mine) but holy s*** did it pull hard!  So I put the reduced timing tune back in it. I even logged the stock tune too and the highest point, it's pulling 6.25 degs.

Anyone else have knock issues with 91 octane? I run only BP or Phillips so I'm trying to feed her good gas...

[BiGMaC]

Sounds like something is wrong with the car (ECU will pull timing all by itself as you know) or the fuel. ?turbo leak, plugs gapping/failure, poor fuel... 93 can actually be 91? Fuel is my first guess given the detonation you had.

[glock-coma]

I've been logging knock also. I have seen as high as 7 also.
I'm running a 93 Unleashed tune. Only in 6th gear going up hill do I see it.  I run shell  93 exclusively

[91hybrid]

All good points. The map sensor data showed consistent 210 to 220 kpa of pressure so turbo leak I think is out. The plug gap may contribute, so I guess I'll pull them and put in my NGK 7's I have on the shelf waiting for the meth kit install. I'm going to run this tank down and go get 5 gallons of 102 unleaded (local station has it on a pump) and log it and see if the knock responds. That should rule out fuel. If that doesn't impact it, I'm kinda at a loss......

[91hybrid]

The max the knock sensors can adjust stock table wise is 7.5 degrees, so anything requiring over 7.5 degrees to be pulled will not be taken out. Meaning you should be careful when your pushing that close to the edge.

Sharing my learning's over the past three days.

John

[SHOdded]

Sounds like something is wrong with the car (ECU will pull timing all by itself as you know) or the fuel. ?turbo leak, plugs gapping/failure, poor fuel... 93 can actually be 91? Fuel is my first guess given the detonation you had.

With BiGMaC on this.  Definitely check the plug gap, should be 0.030.  Also check for chafing knock sensor wires.  Coolant temps are OK?

[91hybrid]

Yeah, temps were all good. Very repeatable. I'll put in the ngk 7's and gap them at 0.028".

[ShoBoat]

If you have the ability check the PCM for the learned octane value. A few of the guys on here have been playing around with this, we believe that the car will pull more timing unless it's at 100%. It's a long shot but you never know.


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[SHOdded]

0.030 is the preferred gap, but see how your mpg does with 0.028.  If mpg drops, then go up to 0.030.  I believe at least one member is currently running 0.032 (almost stock level) and getting even better mpg, but durability is yet to be determined at that level.

[ecoboostsho]

I tend to agree that something is wrong with your car. Definitely check the knock sensor wires as previously suggested, although if you can actually hear the knock then I would be concerned.  You got a reputable tuner so I don't think you've got an issue there. 

Your MAP sensor data converts to 31.9 PSI...I'm hoping that's referenced to atmospheric pressure of 14.7 PSI or you've got a big problem, but even subtracting out atmospheric that indicates boost levels of 17.2 PSI...which would seem kind of high given a 91 octane tune??  That all depends on the amount of timing you are trying to run though as well.

[Needmoreboost]

On my hottest 93 3bar tune max knock was 2.5 ish.  Try new gas station or putting in octane booster to see if it helps.  Then at least you will know if it's an octane issue.  jmo.

[EcoPowerParts]

E85 local? Try putting 2-3 gallons per full tank and see if that helps at all. ECU should add timing back if it's available for no knock.
What's the risk in doing this? If you run out of fuel ECU will close the throttle which you can log quite easily. If you're seeing that you're out of fuel. 2-3 gallons on a tune with 91 octane should be fine and will make a huge difference. If you don't want to do that or E85 not available it's time for a meth kit.

[91hybrid]

I tend to agree that something is wrong with your car. Definitely check the knock sensor wires as previously suggested, although if you can actually hear the knock then I would be concerned.  You got a reputable tuner so I don't think you've got an issue there. 

Your MAP sensor data converts to 31.9 PSI...I'm hoping that's referenced to atmospheric pressure of 14.7 PSI or you've got a big problem, but even subtracting out atmospheric that indicates boost levels of 17.2 PSI...which would seem kind of high given a 91 octane tune??  That all depends on the amount of timing you are trying to run though as well.

Yeah the map values are absolute, so minus 100 kpa for atmospheric. 

[91hybrid]

I do have e85 close buy, so I can try that instead of the 102.

I have a meth kit sitting in my dining room, but I want to understand what going on with my car before I put it on. Want to make sure my cars right.

Thanks for all the replies and insight.

[Boggus]

Little off topic but can you add 2 gallons of E85 to 93 full tank without issues? Will it make a difference to those with 93 tunes and light mods, no meth?