This subject came up elsewhere so I figured I'd throw this thread up here for you smart guys to comment on.
I've looked at the tunes from several well known tuners and vendors, specifically looking at how they set up a vehicle for running E85. It appears to me that the common theme or approach is to simply add ignition timing to the AFR Correction/Alcohol table (12635). All the "Professional" tuners files I've looked at recently only had values added to this table and the other tables are still zeroed out. WTF???
Sorry but to me this seems like the second stupidest way to properly tune for E85 that you could do. The first obviously is simply adding ignition timing to the main High Octane table, that's a good way to blow an engine as soon as your customer goes from running E85 to pump gas. (Which amazingly enough, I've also seen done from "reputable" tuners. And on top of that they copy the High Octane to the Low Octane so the ECM really has no possible way of protecting itself from massively excessive ignition timing.)
So correct me if I'm wrong here. The way these guys are doing this by only adding timing to the AFR Correction table means that they're ONLY getting additional/different ignition timing when in PE or COT. WHY ON EARTH WOULD YOU WANT THAT? The whole point of running E85 is the fact that it needs/is ok with very different ignition timing than pump 91 or 93. So why would you want to still run on your 91/93 ignition timing during 90% of your driving and engine modes? I'll post a couple screen shots below, the first one will be of a log from a well known shop. The white trace is Flex Fuel Timing, the green is EQ Ratio (commanded). As you can see, it's only modifying the ignition timing when it's in PE. So the rest of the time the customer is getting no added benefit from running E85 as far as ignition timing goes. I would even take it one step further, without modifying the ignition timing for the E85, the engine could actually be running WORSE or MAKING LESS POWER than if it was running 91/93 pump gas. So during 90% of this customer's driving the engine is basically running on the wrong ignition timing. Again, WTF? Am I missing something here? Or is this yet another example of just because a "tuner" knows how to change values in a tune and load it in a car, it doesn't mean he knows what the h#ll he's doing?
There's some smart guys on here, can you jump in and let's discuss this? Thanks!
Here's the first screen shot showing the flex timing changes... (The flat part of the white trace is at zero degrees added. The cursor is at max added during PE. So for 90% of this 11 minute drive the ignition timing was basically at 91/93 pump gas timing. Oh yeah btw, this engine was showing an alcohol content of 75%. If he was everyday driving normally or cruising down the freeway for hours and never got into PE, he'd have been running on pump gas timing the whole time.)
Here's the table that I believe should/needs to have values in it. I've never done an E85 tune and left this table zeroed out. This screenshot is from a very well know tuner's E85 with a flex sensor tune...
This is the table I've seen most tuners modifying. Even still, do they think E85 doesn't need/want different ignition timing below 2k rpm? So it's ONLY modifying timing in PE and NEVER below 2k rpm. Weird...
Even the Max Torque modifier table is left zeroed out. Really?...