Bippu147

iTrader: (9)

The map and iat are not going to correct perfectly based on those values. There are too many variables. You NEED closed loop function. Why would you not want to consistently target your ideal AFR?

Not trying to push credentials, I just asked a question that is all. You could touch all the ECU's in the world if you want, doesn't mean a thing if you haven't successfully tuned a car. I asked because I want to know how much experience you have when it comes to tuning cars and if you know what these load tables look like. Fixed map is always set to a "safe" value in the ECU, and then fuel is trimmed accordingly.

I don't think the latency would really matter. I've tuned lots of cars with a base injector control map and corrected the fuel via percentage. I'll take some screen pics and upload them in a bit.

Hardrvin

MAP and IAT are pretty capable, but agree still not perfect. To which, I think back to the original point, we all agree that you should not disconnect O2 as a fix. It's a lousy band aid.

Define "fixed table." If you mean by disconnecting the O2 and going fixed limp map, then yes, it'll be just that, limp. If you mean, fixed as in the called for target AFR, then I'm going to disagree. And my main arguement, what do you think happens when you go WOT? You're not closed loop anymore? If it was of such dire consequence to run w/ O2 input, than why does every ECU go open loop at high/full load conditions?

You mention not pushing credentials, but then push buttons again by implying I can play all I want but that doesn't mean I'm sucessful. Not sure if it's intentional or not...but yes, I have sucessfully tuned a number of cars and in various trims.

Latency will become an issue when you really want to trim in really close. Generally, it's nothing that the O2 cannot account for...if it's connected.

JeffTsai

iTrader: (1)

When the ECU goes into open loop under WOT. It doesn't do it blindly. On cars with MAF sensors, the air metering is still in place as well as intake temp and coolant temp compensation. On MAP sensor cars, that metering is in place as well as the barometric compensation and air temp. It's using the data collected from the other sensors(besides o2) combined with known maps to output the fueling. On the older cars before they were equipped with wideband from the factory, the car would obviously go into open loop under WOT because the narrowband oscillates at 14.7, and is pretty much useless at the AFR range the engine operates under WOT load.

On newer cars that have wideband/lambda sensors in place, they have full fuel trim control during all times. The earlier generation of wideband equipped cars had slower responding systems so they would go into semi open loop as well under WOT because sensor feedback speed was not fast enough to deem it safe to operate under WOT. The ecu would still alter long term fuel trims under WOT, but not the live short term correction. On the more recent generation of factory cars equipped with lambda sensors, the sensor and processing response rate is very fast and they are generally under closed loop short term correction at all times. These newest generations of cars with full time short term correction are a serious PITA to work with lol.

Hardrvin

I hope you're not implying that I suggest it uses zero sensor input. If it didnt, how would it have half a clue of how much fuel to put in. Hence i specifically stated open and closed loop to point out O2 control or not, not complete blind firing of the injectors. Heck, how do address a fuel table with no input. Do I need to point out cam crank sensors or are you guys going to try to point those out to me and state I'm an idiot for not knowing they exist because I haven't brought them up?

Jeff, another random thought or point, be careful using an A/F to try and tune a car if its mounted pre turbo as the pressure skews the reading.

gdoutlex

iTrader: (4)

im doing an NA-T on a 97 sc300 with a aem FIC, and just wondering if any of you guys have a basemap i can start with?