Okay, I'm getting to know how to tune the fuel curve pretty well. I'm having some problems on the spark curve though. How do I know when I need to add advance or take away advance to the spark? In other words, what do I need to look at on the scanner when tuning the spark curve? How do I know when I have it at the optimal level? Also, I was taking a look at the spark advance for power enrichment. Why does it go up, then down, then back up again as the RPMs increase? I would think that there would be a correlation between advance and RPMs. This is for a 730 speed density ECM if it makes a difference. ANY help would be greatly appreciated. Thanks.

 

Anyone have any advice? Thanks again.

 

if you can get to a chassis dyno tune for peak TQ in every load point. and if NOX2 becomes an issue put EGR back into to bring it down. then adjust fuel to get hc co co2 back into spec and youll look golden.

 

What does that have to do with spark timing? Thanks for the reply.

 

spark timing has a very direct effect on combustion efficeincy and TQ output. if the timing is over or under advanced the TQ will fall off. so its the best way ive sen yet to really get the timing nailed. then again fuel trim will also affect TQ ouput but not nearly as much as timing will.getting the falme to burn at the appropriate time will increase combustion pressure resulting in more TQ. i hope this clears it up ??

 

Yeah, that makes sense now. Only problem is, I don't have access to that kind of equipment. Any other suggestions?? Thanks again.

 

Okay, I've done a bit of research and here's what I have come up with. At part throttle, you want to add/subtract timing until you get the least amount of TPS for a given speed. Also, less engine vacuum is desirable at a given speed. Is this information correct?? What about WOT, how do you know when you have max power without using a dyno?? Thanks again.