SC400-V8

iTrader: (1)

Oh *****. That explains ALOT. My motor is completely stock, event the intake assembly is original... no wonder it only remains ultra powerful for a few days and then goes back to "pretty damned powerful." Well, this sucks.. Does this mean if i were to do a few other mods, like the torque converter and exhaust in the future, the ecu might actually have more effect?

THE_CEO

NRG has a very valid point!....i think it would be logical to do the ECU upgrade once you have all of your mods on your car...and not before.

CEO

Vegassc400

I think I got the gist of what NRG was saying now.

That is very true. Leo over at WR told me to make sure to get my exhaust and intake done before adding the ECU. The program would not work as well on the stock components.

SC400V-8, you should consider a BFI and exhaust pretty soon. Good luck.

Lextreme

Maybe the Lexuspros ECU needs to be reset every few days. True Cold Air Induction like the Mustangs is coming up. I am working on it right now on a LS400 and it should work on SC400. I will have proven dyno data for you guys with and without CAI. Therefore we will have objective and measureable proof of gain or lost.

JBrady

Guys, there seems to be a lot of confusion here. First of all, understand that the factory "tunes" the engine to be conservative. By that I mean that they have NO idea what any given owner is going to do with the car. High compression engines want high octane fuel (within reason, 93 octane is high) but we all know some people will pump regular 87 octane into their cars. The factory knows this AND they know that fuel quality changes from region to region and season to season. Also operation conditions vary with altitude and temperature. All this and we haven't even talked about maintenance. The factory wants happy customers even if the customer is in a poor fuel area or doesn't maintain their car optimally. So, the factory does NOT tune the car to its peak. In other words the factory programming has a richer fuel mixture and less ignition timing that the engine could actually use under ideal conditions.

Now, to modify the fuel and timing you need to change the ECU "map" for the ranges you want to effect. This is MUCH harder than it sounds as the "map" is multidimesional and there are MANY variables. So, using an ECU modifyer you attempt to lean the fuel and increase the spark to just shy of the point of detonation. This WILL produce MORE power and torque on ANY engine regardless of modifications. Usually, if you modify your engine this programming MUST be changed or you will cross over into detonation. Just exactly how MUCH more power I cannot say but the process above is true for nearly 100% of factory cars. That is not to say that there is a computer upgrade available for all cars but rather all cars could make more power if optimized.

Now, one of the main problems with doing this is mentioned above... the very complex "map". It is VERY hard to tune an engine at the "edge" without having SOME part of the map go over the "edge". When the engine senses ANY detonation it will pull timing back and possibly richen fuel as well (depending on the ECU). This is why the above examples needed to be re-set every so often to get back the gains. Re-setting the ECU brings it back to the original settings from the factory and that is the baseline that the tuners will start with to retune with their upgrades. A bit of a hassle yes, but, still not a huge issue for an easy power boost.

Vegassc400

JBrady is dead on. Keep in mind that most ECU mods also advance the timing. I believe that mine has about 15 degrees of timing advance as well as modifying the AF ratios and raising the rev limiter.

DO NOT plan on doing a nitous kit or forced induction with these ECU mods. The advanced timing and leaned fuel will cause massive detonation.