OAR deviation concern

[Marvinmadman]

You can also try a bottle of octane booster.

If I have a bunch left in the tank I will.

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[jbailer]

Remember also, OAR adjusts with very light load and you don't want any slosh so no bumps and sharp curves or fast stops.

It also adjusts best with maybe 1/2 to 3/4 tank of gas. Too little sloshes more, same with too much.

 

[Marvinmadman]

Yep. Nothing but easy miles with my wife

 

[TEXAS HEAT]

That sounds like a fuel issue. The OAR should be able to get to -1 on 91 octane. If you're running 93 and you're at -.96, I think it's the fuel. What brand gas and have you tried another? Does the fuel you're using have a 10% ethanol mixture? I don't know if or how much that impacts it but my guess is it would help. It seems almost all gas stations now use the e10, I think it's cheaper and helps them hit the octane number at a lower cost. That's just a guess though.

A negative .96 is almost a -1, so that is not necessarily bad.

Negative ignition corrections can and will occur as our ecu's continue to add timing up to a point until it see's knock, then it will begin to lower it until the knock goes away. It's the severity of the knock that is important. This can be determined by monitoring the negative ignition corrections. Anything more than -3 is concerning. A tuner has the ability to modify how the engine deals with knock events. This can be very tolerant or very tight, depending on the tuners strategy.

Now that Summer is upon us, you're more likely to see negative ignition corrections as CAT's increase. You will see these at part throttle and a wot, but again severity is what you need to be concerned with. You can help to mitigate this by adding 1 gallon of e85 to a full tank of 91-93 which will bring regular e10 gas to e15. The ecu can handle this as our cars are rated for up to e15 fuel. You can see this in your stft's, because it will have to add fuel to compensate for the greater amount of ethanol. Honestly, this is a great way to keep knock at bay during the summer month's if you have it available to you.

I've actually used 1 gal of xylene plus 3oz of marvel mystery oil to a tank of gas to increase the octane on my Mazdaspeed before e85 was available in my area. The Sherwin Williams people looked at me kinda funny after my third trip to the store just to buy Xylene though. lol

 

[Marvinmadman]

My knock is at light pedal situations, no where near WOT. Like 15-20% pedal and under 0 psi. If I go WOT the knock goes to 0

 

[TEXAS HEAT]

My knock is at light pedal situations, no where near WOT. Like 15-20% pedal and under 0 psi. If I go WOT the knock goes to 0

Are you seeing negative ignition corrections when this occurs?

 

[Marvinmadman]

I'll have to log it to see. I don't think I was able to display that on the X4

 

[TEXAS HEAT]

I'll have to log it to see. I don't think I was able to display that on the X4

If your OAR stays at -1 then the knock events aren't likely very severe. If you can't monitor those parameters live on the SCT, you could monitor your OAR which will give you an overall idea on how severe the knock events are. If the knock events are severe it should directly effect your OAR, depending on your tuners strategy.

Try a little octane boost and see if it continues to knock at part throttle.

Also, a little knock as you're spooling up at part throttle is normal as long as it goes away once the load levels out.

 

[Marvinmadman]

I'm still on the stock tune lol. I want to monitor my car on the stock tune for a while before I tune it. I'm weird.

 

[TEXAS HEAT]

I'm still on the stock tune lol. I want to monitor my car on the stock tune for a while before I tune it. I'm weird.

Gotcha! The factory knock strategy is very aggressive and will pull timing very quickly to get everything back under control, especially if your CAT's are above 120F. You're lucky to get any timing advance in that scenario.

 

[CustomS550]

Well, if I can't rag on the mustang in real life, i certainly can in Assetto Corsa

http://www.mustang6g.com/forums/showthread.php?t=83559

 

[CustomS550]

You guys see how rich the factory tune is in my stock log? It was down to 9.99 AFR in the higher rpm! The good news is that the ECU was adding up to 5 deg. of timing towards the end of the pull in the upper range of the rpm.

Gotcha! The factory knock strategy is very aggressive and will pull timing very quickly to get everything back under control, especially if your CAT's are above 120F. You're lucky to get any timing advance in that scenario.

 

[jbailer]

A negative .96 is almost a -1, so that is not necessarily bad.

Negative ignition corrections can and will occur as our ecu's continue to add timing up to a point until it see's knock, then it will begin to lower it until the knock goes away. It's the severity of the knock that is important. This can be determined by monitoring the negative ignition corrections. Anything more than -3 is concerning. A tuner has the ability to modify how the engine deals with knock events. This can be very tolerant or very tight, depending on the tuners strategy.

Now that Summer is upon us, you're more likely to see negative ignition corrections as CAT's increase. You will see these at part throttle and a wot, but again severity is what you need to be concerned with. You can help to mitigate this by adding 1 gallon of e85 to a full tank of 91-93 which will bring regular e10 gas to e15. The ecu can handle this as our cars are rated for up to e15 fuel. You can see this in your stft's, because it will have to add fuel to compensate for the greater amount of ethanol. Honestly, this is a great way to keep knock at bay during the summer month's if you have it available to you.

I've actually used 1 gal of xylene plus 3oz of marvel mystery oil to a tank of gas to increase the octane on my Mazdaspeed before e85 was available in my area. The Sherwin Williams people looked at me kinda funny after my third trip to the store just to buy Xylene though. lol

[MENTION=27727]Marvinmadman[/MENTION] already said it but I was going to say, that is on the stock tune, would be a different story if it was a pro tune. A -.96 when he's using 93 octane is enough that I'd be concerned. Since the stock tune should be able to get to -1 easily on 91 octane and he's using 93. It would at least have me looking for other gas which I think is the most likely cause.

There's always knock, even if you can't hear it. The ECU uses it to adjust and push the timing for performance. The knock sensors are very sensitive and Ford calibrates the sensors to the specific knock signature for our engine. Too much intensity of the knock means the ECU isn't able to correct for it. That's when you have to worry. Lots of people think they have knock with the EB because of the noisy, rattly 4 cylinder then find out it's normal. If you're really getting timing corrections for it and [MENTION=24222]TEXAS HEAT[/MENTION] gave some good examples of what to look for, that's a different story. Either way though I would use a different source for gas.

 

[Marvinmadman]

I'll get on it this weekend for sure.

 

[jbailer]

You guys see how rich the factory tune is in my stock log? It was down to 9.99 AFR in the higher rpm! The good news is that the ECU was adding up to 5 deg. of timing towards the end of the pull in the upper range of the rpm.

I know! Crazy right?! That's normal for the factory tune and way too rich in my opinion.

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