Most of the changes in a tune are in the Fuel and Timing Maps. When tuning the car do you modify just the the Hi Octane map or both the low and hi octane maps?

 

you gonna have to change the Low Octane Maps once you made some changes in the High Octane Maps. thats what i do and not seeing any problem...

 

Depends if you want a failsafe tune that your ECU will look at and incorperate when you experience knock.. Most tunes that I have looked at that were done professionally do not utilize this feature..I typically add some fuel and lower the timng in the low octane maps in case I get some bad gas or something, but my octane level is pretty much constanly at 100% on my car.

 

I second petey on this. I've done enough pulls to know my car pretty well, and from what I've observed, my AFR's are pretty much dialed in and consistent from run to run. Timing, on the other hand, is a little more unpredictable, esp with different gas, temp changes, load changes (hills, etc). So with that in mind, I chose to keep my High and Low Fuel Maps the same, but I pull a couple degrees timing on my low octane map just to be safe.

Just to note, since switching to e85 I've never seen my logged octane drop below 100, but I still run the Low Octane Timing map delta just to be safe. I've seen enough tunes with both maps the same and "sea of 8's" blocks, but this is my car and I would never run that ragged.

 

Both should be updated when you get tuned or tune it yourself.

The Low should be considerably safer than the High.

There are a few bad practices around:

1) Setting Low & High to the same. This essentially removes the protection the Low Octane maps are there for in the first place.

2) Leaving the Low Octane map stock. This can be dangerous, especially a big turbo or running high boost. If you have bad gas and fall onto the Low octane map, and then constantly running -10° of timing (which is what the stock Low octane map calls for in high load columns) then your EGTs will skyrocket. If this went on for an extended period of time, you could have considerable heat damage.

My recommendadtion is to tune the High Octane map for little to no knock, and then once it's complete, adjust the Low Octane map to be a tamer version of your new high octane map. This goes for both Fuel & Timing.

 

Amen to the above two posts.. I believe tuners keep them the same to make more power on the dyno for your custom tunes which makes the customer happy and re-assured not knowing that once they hit the streets or the track the truth comes out.
I am in no way bashing ANYONE and there are alot of great evo tuners on theese boards but I have to call it as I see it

 

I agree. My fuel maps are basically the same.
But my low oct timing map is about 4-5* shy of my high octane map.

~I HAVE to run it this way as maft pro will a/f track your engine into oblivion if it starts knocking. (It holds a constant preset A/F ratio off the WB.) So the ecu can 'ask' for additional fuel to drown the knock and it just keeps holding your input A/F ratio. So in my case the fuel tables are fairly worthless as any kind of a safety mechanism.~

But its not a bad way to do it even on a car without additional fuel controlling devices. I would maybe richen up the low map a few tenth's of a point too just to be on the safe side.

Safe is good.


Who's playing crazy 8's?