False knock/Bad fuel issues

[hendo]

Is anyone in the upstate south carolina having problems finding good fuel?
since january ive been told that i have low quality fuel.

back story of whats going on. January of this year i did some logs and sent them to my tuner, he told me the fuel quality was low , but he would go ahead and send me a base file. I got the base file in and sent in some more logs and got my final revision.

two days later i went to the track and to my surprise i didnt pick up a single tenth from the tune (car is an a6).

fast forward to late feb/early march and I put on a jlt intake and an offroad xpipe.
i get the base file for the jlt and log it. I was told the fuel quality was so bad that he would not tune it and definitely would not send me my nitrous file.

i then ordered some torco and logged with that in, i was told the fuel quality was on par with 91 octane winter blend.

after that i ordered a 5 gallon drum of vp c20 and mixed it 5:1 with shell 93 octane fuel, logged it and sent the file in, again the tuner said it looked like 91 octane winter blend.

at this point i figure it must be false knock, maybe the xpipe rattling around. so i put the car back to stock and logged it that way, car has no knock activity and is making 23* timing, so i leave it stock and add the tune from january and its pulling 3.5* timing.

im beyond frustrated at this point. im already 350 deep in the tune and 100 deep in torco and race fuel trying to chase the problem.

any ideas what to do next? any help would be greatly appreciated.

 

[Weather Man]

Telling you the specific octane by looking at your tune smacks of serious bullshit. Time for a new tuner.

 

[ajpturbo]

Is anyone in the upstate south carolina having problems finding good fuel?
since january ive been told that i have low quality fuel.

back story of whats going on. January of this year i did some logs and sent them to my tuner, he told me the fuel quality was low , but he would go ahead and send me a base file. I got the base file in and sent in some more logs and got my final revision.

two days later i went to the track and to my surprise i didnt pick up a single tenth from the tune (car is an a6).

fast forward to late feb/early march and I put on a jlt intake and an offroad xpipe.
i get the base file for the jlt and log it. I was told the fuel quality was so bad that he would not tune it and definitely would not send me my nitrous file.

i then ordered some torco and logged with that in, i was told the fuel quality was on par with 91 octane winter blend.

after that i ordered a 5 gallon drum of vp c20 and mixed it 5:1 with shell 93 octane fuel, logged it and sent the file in, again the tuner said it looked like 91 octane winter blend.

at this point i figure it must be false knock, maybe the xpipe rattling around. so i put the car back to stock and logged it that way, car has no knock activity and is making 23* timing, so i leave it stock and add the tune from january and its pulling 3.5* timing.

im beyond frustrated at this point. im already 350 deep in the tune and 100 deep in torco and race fuel trying to chase the problem.

any ideas what to do next? any help would be greatly appreciated.

I would look into a second opinion....Call James Gordon of tuning by James...Maybe just see what he has to say...You can talk to him personally

 

[Shaun@AED]

90% of the time we see *false knock* it's Exhaust rattles / leaks / knocks. Sometimes it's as simple as the driver side Factory Converter to H-pipe bolt being installed upside down tapping on the floor board when the engine torques over. Other times it's the exhaust hitting the axle on launch and hard shifts. I've seen exhaust leaks at the flange trigger knock sensors.
I've also seen Blower discharge pipes tapping the engine every so slightly picked up by the knock sensors.

 

[Weather Man]

90% of the time we see *false knock* it's Exhaust rattles / leaks / knocks. Sometimes it's as simple as the driver side Factory Converter to H-pipe bolt being installed upside down tapping on the floor board when the engine torques over. Other times it's the exhaust hitting the axle on launch and hard shifts. I've seen exhaust leaks at the flange trigger knock sensors.
I've also seen Blower discharge pipes tapping the engine every so slightly picked up by the knock sensors.

Would you ever tell a guy his fuel octane by looking at a log?

 

[Shaun@AED]

Would you ever tell a guy his fuel octane by looking at a log?

Fueling vs Knock vs Spark I can generally tell the fuel quality when logged, but I can not rule out *false knock* until true race gas is run.

 

[Weather Man]

Fueling vs Knock vs Spark I can generally tell the fuel quality when logged, but I can not rule out *false knock* until true race gas is run.

That I can believe. But to say winter 91 goes a bit to far.

 

[Joey8]

I was told by Shaun I had bad gas as well. Thats why I was seeing a bunch of knock. I threw a can of torco in and it was gone. That shows that it was bad gas rather then an exhaust leak. Try to put a can or Torco in and see if that gets rid of the knock.

 

[Shaun@AED]

That I can believe. But to say winter 91 goes a bit to far.

It's all relative.

Butane was added in fair amounts to 'Winter Blend' fuels, and although Butane has a high octane, it's a vapor at room temperature. Adding it to fuel results in fuels that can not take as high of cylinder pressure as fuels that do not have Butane added, even though the overall *octane* is the same.

 

[jestang]

I will vouch for the op regarding this as I was there the day we first ran the car with the tune. It ran the same (well actually a hair slower) with the tune installed as it did stock 30 minutes before. It obviously isn't bad gas at this point and if it's mechanical, it must have came that way from the factory though the times it ran stock tell me everything is fine mechanically. I just wish we could get it figured out and on to making some better passes.

 

[Justin81]

I'm seeing some knock activity in my car. I'm not sure how to read it but it's there. I'm wondering if I should try changing the fuel over to the Torco or similar. I run only Sunoco 93 in it right now.

 

[Shaun@AED]

I had a car at the shop recently that we did new exhaust and tuned.
On the dyno I saw some knock pop up so I adjusted the timing curve accordingly, but the knock was still present. I knew right away it was likely *false* as I know the fuel in the area, I know these cars, and I know my chassis dyno / what these cars can take.

As I crawled under the vehicle looking for a common mistake (Driver side cat to midpipe clamp installed upside down for ease of use causing it to knock the floor board on hard accel), I found the cause of the knock. It was not the bolt hitting the floor board, but the Cross over of the X pipe hitting the Transmission cross member on hard accel. The exhaust was ~1/16th of an inch away from the cross member on the driver side. As the engine torqued over during WOT the exhaust would tap the Trans cross member and the knock sensors picked it up. We moved the exhaust and had no more knocking issues.

These knock sensors will pick up ANY knocking on the vehicle. Exhaust pipes hitting something over the axle? They will pick it up. Even exhaust leaks I've seen knock sensors pick up.

 

[Justin81]

Thanks Shaun. I have a lift I need to put this car up and check over everything. I had a Catless H-Pipe and Gt500 AB put on. I think it's a leak or rattle of some sort.

 

[Sick_Mustang]

I have also come across false knock. In regards to loose exhaust piping when I was trying out different exists setups, forgot to tighten on side of the x pipe all the way.