Thread: Lean?

Originally Posted by Smokin2000gtp

So correct me if I'm wrong, but since I want to go by my LTFT's instead of the narrowband O2 readings, should I lean it out since my LTFT's are at like -10? I really don't know if I'm supposed to add or subtract fuel. Well since negative LTFT's mean you're running rich and the PCM is pulling fuel I would think that you would lean it out, but my only concern is that the O2 readings were indicating that I was running lean. I know narrowbands aren't worth a ****, but if my car is really running lean and I lean it out more that would not be good. I'm confused and need help.

No, you don't want to lean it out. The PCM derives it's WOT LTFT from LTFTs during the rest of your driving. It does not use the O2 sensor during WOT. You need to do VE and MAF tunes to get your normal driving LTFTs as close to zero as possible. That'll bring your WOT LTFT back to zero, thus raising your O2s.

On the subject of the O2 sensor, it isn't useless. It's good for relative measurements. My 890 might not be as rich as your 890, but if I was seeing 890 and I'm now seeing 850, I know I'm leaner than before. See?

Originally Posted by Sabrewings

On the subject of the O2 sensor, it isn't useless. It's good for relative measurements. My 890 might not be as rich as your 890, but if I was seeing 890 and I'm now seeing 850, I know I'm leaner than before. See?

Good advice the narrow band o2 sensor is very helpfull and though it may not be the greatest way it's the way i have been doing it all along. You can get pretty close. I should wthout a doubt have a wide band by now and am going to be ordering one soon.


Anyway If you kept the stock tune wich you should have flash that back onto the pcm with the stock MAF table. Next reset the fuel trims then do a maf tune from 0 - 7500 hrtz on the MAF table hitting all the cells as many times as possible. three seperate drives of 30 minutes should do it. flash the new numbers after each 30 minute drive. This will take care of your fuel trims at idle and part throttle. This will get your car where it is suppose to be at...not lean not rich. Next move onto wot tuning. This really shouldnt be done without a wideband...but ANYWAY go wot and look at your o2's....you probably shouldnt run any less than around 940's being prety much stock...stock o2's are generally around 960's on a stock gtp.


Then if your to low on your o2's highlight the 7650 on up section and increase by a small amount. This is basicly tricking the pcm and saying that there is more air comming into the engine thus giving it more fuel. Flash and drive then go wot again and look at your o2's and adjust accordingly...simple as that and I can gurauntee that you wont have any problems doing it this way.


But you need to get real firmiliar with how the tuner works and how to use the histrograms. There your best friends in the long run. And it will make it a lot easier on your self if you do it this way.


And

Thanks for the advice. Now I need to start reading up on tuning lol.