Still getting some ST Knock

[Oldschool1975]

U7135
Software Version 9r28
09 SRT8 Challenger 6 speed.

Hello. Been doing some data logging and I have done some timing adjusting 1st, and now fuel adjusting. Want to make sure I am going the right way with the adjustments.

I'm getting some slight ST retard in the 4k and up range. 1.5 degrees here and there. I have only taken 1 degree out in the 4k-4.8k and 5k-7k range, then added a total of 2.5% more fuel in the 4k-4.8k range, and 3% more fuel in the 5k-7k range. Would adding more fuel help, or do I need to take more timing out?

Thanks,
Michael

[brandy16]

Bad idea to play with the timing unless your on a dyno.

[Oldschool1975]

I've done some tuning before and have also researched about people taking timing out with the 93 tune. Taking 1 degree out isn't gonna blow up any motor. Thanks though.

To the Diablo guys, your opinion would be appreciated.
michael

[Mike_Levy]

Add 5% fuel in the upper 2 ranges. That will show if the fuel is the problem or if theres something else causing the knock (like perhaps its false). If knock retard increases when you add gas, then the gas is the problem.

[dnar]

Yeah, try adding more fuel. You have not added much. I am at +14%, +12%, +12% with my tune! You might find you can leave spark at zero once fuel is right, assuming lean running is the cause (often is). Increase to 6% then try 9% - 12% until knock is gone.

[Oldschool1975]

Thanks for the replies Mike And dnar.

I added a total of 6% fuel to the two upper rpm ranges, still some knock. Added 9% to the two upper rpm ranges and there is know ST knock through the 1st three gears. I only got .5 ST knock in 4th, in the upper range. Could this be a false knock or should I add alittle more fuel to the 5k-7k range? Say 1%?

Then I guess I could add the 1 degree timing I took out to the 4k-4.8k and 5k-7k range and log again? If it has ST knock again, would adding fuel be the next step, or taking the 1 degree back out? I think adding more fuel, but would like educated opinions. Not adding anymore timing than the factory Diablo programs, just going back to what the programmed with the 93 CAI tune.

I also have not touched anything in the lower rpm range, there is know knock. Should I leave the Diablo settings? Is there anything I could do to get more power in the low range?

My mods are a catback from B&B that I took out the back mufflers/resonators, 180 stat, and a CAI.

Thanks,
Michael

[DGatzby1]

Oldschool if you are changing the 93 octane tune, you may want to just try the 91 octane tune. You may be surprised. That may work fine as is.

[Oldschool1975]

Oldschool if you are changing the 93 octane tune, you may want to just try the 91 octane tune. You may be surprised. That may work fine as is.

Tried the stock 91 CAI tune and it felt the same as the stock 93 CAI tune. Felt no difference from stock. So I started tuning on the 93 CAI tune.

Michael

[dnar]

The only difference between 91CAI and 93CAI is +2 degrees at all three ranges at WOT.

I find I need more enrichment the lowest rev range. Be aware that any knock in the first range may "linger" in to the mid and upper range. Look at the chart, work on the range that the knock first appears first.

I found it quicker to add the same amount of fuel across the board to start until all knock is gone. It is normal to get maybe 1 degree ST retard especially at the point of gear changes.

BTW, with +14% at the lowest range, my Hemi now launches like a rocket and smokes tyres like no ones business. When I first tried the 93CAI tune, most of my knock was very bad around 2-3K rpm. Hence I now run +14, +12, +12. This is the sweet spot for my standard engine with CAI and Good Cat back exhaust.

I find it helps plenty (without much loss) to cut 1-2 degrees across the range with the 93CAI tune with my fuel.

[Oldschool1975]

Ok, we had some rainy days here so I just today got a chance to datalog again. I added a total of 12% to the upper two rpm ranges and put the timing back to stock in the 93CAI tune and the knock is gone.

It's still rainy here, so when it clears up I'm gonna put the stock tune back in it and do some 0-60 runs. See if I can feel the difference also. It feel good lately (more so with 1 degree taken out in all ranges), but I don't know if it's all in my mind.

About a month ago, on a 400 mile trip, I got 24.87 with me doing the math. I was impressed. So I now get to take it on a 500 mile round trip and see what kind of mileage I get after the tuner.

Thanks everyone for your input.
Michael