02denali Posted February 10, 2004 Report Share Posted February 10, 2004 The dual tuning is nothing new or invented. The pcm has two tables, the low octane and the high octane table. For those who use the high octane gas, you can benefit from having two high octane tables, this is accomplished by copying the hi to the low. For those who run low octane, both tables are alterered for better performance, but you're not paying for "daul tuning" it's already built in. The tuner is just making sure you'll notice a performance increase whether you're running good or bad gas.The pcm will switch between the two tables based on how much detonation is detected. Keep in mind the pcm is not "dual tuned" there's not such thing, lol, all it is , there are two tables, one protects you from detonating your engine to death and the other is used when no detonation is detected. Link to comment Share on other sites More sharing options...
Farmtruc Posted February 10, 2004 Report Share Posted February 10, 2004 Yes, you're absolutely right. When someone gets a tune, most of the time if the tuner is good, he will modify both octane tables. The tables are for low and high octane fuel. When the pcm detects excessive knock it will turn to the lower octane table for its values. If there are no signs of knock/detonation, it will use the high octane table. This is built into the pcm already. When someone orders a pcm and wants an aggressive tune (such as yours) I'll copy the modified high octane table to the low one. This will ensure you are getting max timing. This sounds as if there's no protection and the engine will knock. If you're always running high grade fuel that is not a problem. I guess you could spice up the terms and say you tune for multiple octane levels, but it's actually already there. Tuners just mod both hi and low tables to increase performance regardless of what table your pcm is using. I guess I offer dual octane tuning, lol. later, allen Link to comment Share on other sites More sharing options...
MN C5 Posted February 10, 2004 Report Share Posted February 10, 2004 Yes, you're absolutely right. When someone gets a tune, most of the time if the tuner is good, he will modify both octane tables. The tables are for low and high octane fuel. When the pcm detects excessive knock it will turn to the lower octane table for its values. If there are no signs of knock/detonation, it will use the high octane table. This is built into the pcm already. When someone orders a pcm and wants an aggressive tune (such as yours) I'll copy the modified high octane table to the low one. This will ensure you are getting max timing. This sounds as if there's no protection and the engine will knock. If you're always running high grade fuel that is not a problem. I guess you could spice up the terms and say you tune for multiple octane levels, but it's actually already there. Tuners just mod both hi and low tables to increase performance regardless of what table your pcm is using. I guess I offer dual octane tuning, lol. later, allen Good luck finding your PCM running on the Low Octane Table. It works a bit differently than you described. Based on my data logging I've never seen any of my vehicles run on the low octane table purely. But to each his own.. IMHO a properly tuned vehicle wouldn't need both the high and low tables copied over each other. There is a positive side to having two tables for the PCM to reference. Link to comment Share on other sites More sharing options...
PCMFORLESS Posted February 10, 2004 Report Share Posted February 10, 2004 Also, even if on the 93 octane programs we (tuners in general) copy the High octane table to the low octane table (I usually do this and then still subtract 2 degrees, just in case you get a bad tank of gas) the truck/car still has the ability to use it's knock retard to pull timing and protect itself. In the LT1's there never was a low octane table like the LS1/trucks have. I don't typically do the dual octane tuning as I don't like using the low octane table unless you would happen to get bad gasoline. I set the timing tables to the gasoline you intend to run, but can do the dual tables if a customer would like it. Later, Bryan Link to comment Share on other sites More sharing options...
MN C5 Posted February 10, 2004 Report Share Posted February 10, 2004 My First point was that the PCM doesn't run off the Low Octane Table. And a two degree differential isn't enough IMHO. The second point "There is a positive side to having two tables for the PCM to reference" if you know how to use it why wouldn't you? Link to comment Share on other sites More sharing options...
zippy Posted February 10, 2004 Report Share Posted February 10, 2004 if i recall from a class from way back, the only way it'll use the low octane tuned program is if knock is detected for an extended period of time (i don't recall how long it was) and the knock retard had to be something like 6 degrees or more. it pretty much has to be about coming apart before it'll switch tables. Link to comment Share on other sites More sharing options...
Fun Guy Posted February 10, 2004 Report Share Posted February 10, 2004 I was stuck on the low octane timing table, which was one of the issues Magnuson found when attempting to resolve me realizing only a 60rwhp gain from their Radix.... Link to comment Share on other sites More sharing options...
BigTex Posted February 10, 2004 Report Share Posted February 10, 2004 O2 and farmer - I find it kinda interesting that you make the same post and reply - word for word - on multiple bulletin boards. Link to comment Share on other sites More sharing options...
zippy Posted February 10, 2004 Report Share Posted February 10, 2004 where is the other? LS1tech? Link to comment Share on other sites More sharing options...
PewterC3 Posted February 10, 2004 Report Share Posted February 10, 2004 Sounds like to me Nelson is not the expert he claims to be and he's using 02 Denali is his less then expert spokesman! I though it was kind of funny that 02 Denali starts the thread and Allen is the next post. Coordinated? Link to comment Share on other sites More sharing options...
Farmtruc Posted February 10, 2004 Report Share Posted February 10, 2004 O2 and farmer - I find it kinda interesting that you make the same post and reply - word for word - on multiple bulletin boards. I guess I could have retyped it, but I saw that 02 put it on several boards, so i figured i'd reply to it, copy and pasting is much easier than typing it again. I was logging a truck one time and noticed thier total timing was quite low, there was no knock detected and the high octane table was obviously higher than the lower one, I copied the high octane to the low and his timing increased, still no kr. I'm not sure what kept this truck in the low octane, but running off of either the low or high , when they're the same doesn't matter i guess. I"m sure a reflash would have fixed it, but so did copying the tables. Anybody have some real info on when a truck decides to switch from the high to the low and what keeps it there? Funguy, did magna find out why or did they just start from scratch with a new pcm? thanks, allen Link to comment Share on other sites More sharing options...
BenKey Posted February 10, 2004 Report Share Posted February 10, 2004 Sounds like to me Nelson is not the expert he claims to be and he's using 02 Denali is his less then expert spokesman! I though it was kind of funny that 02 Denali starts the thread and Allen is the next post. Coordinated? I think it was just a ribbing. I don't think anyone was calling Allen out. His results speak for themselves. By the way, what purpose did the posts serve? None, other than to explain things to you. Link to comment Share on other sites More sharing options...
Farmtruc Posted February 10, 2004 Report Share Posted February 10, 2004 Sounds like to me Nelson is not the expert he claims to be and he's using 02 Denali is his less then expert spokesman! I though it was kind of funny that 02 Denali starts the thread and Allen is the next post. Coordinated? btw, if you haven't noticed, I'm always online and check the boards fequently. later, allen , we were discussing this topic during the dyno day and of course I'm going to reply to it. I haven't seen anyone else provide facts on how a pcm decides when a truck wants to go to the hi or lo tables. I have my theories just like anyone else does and they haven't been shot down, so until someone comes up with facts I'm sticking to them. This isn't a setup or conspiracy, just to get some info flowing on the boards. Link to comment Share on other sites More sharing options...
Farmtruc Posted February 10, 2004 Report Share Posted February 10, 2004 ... And a two degree differential isn't enough IMHO. Yes it is, at the dyno, the more timing you can squeeze out of a truck the more power you're going to see. One of the guys at the dyno was able to get 2 degs out of his truck, that equated to 8hp. Sure there are several other factors, engine temp, air temp, coolant, but this was on a good dyno and not a dynojunk dyno. So, I do trust it's accuracy. Would you care to share on how the pcm determines what table is active? I'd honestly like to know. I've heard a lot theories and they will always be debated. thanks, allen Link to comment Share on other sites More sharing options...
Farmtruc Posted February 10, 2004 Report Share Posted February 10, 2004 Sounds like to me Nelson is not the expert he claims to be and he's using 02 Denali is his less then expert spokesman! I though it was kind of funny that 02 Denali starts the thread and Allen is the next post. Coordinated? Hey, PewterC3 that makes you at 21 posts congratulations. Thanks for the informative reply. Link to comment Share on other sites More sharing options...
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