where do i even begin???

[Knightmare1981]

So first off let me just say that i am a 100% noob, I started reading thru all the tuning forums and car forums trying to learn everything I could in my search of power and efficiency(ok, mostly power, lol). I scanned my car (2004 Monte Carlo SS L67) after resetting the LTFT's and letting them relearn for abou 40-50 miles and now my LTFT's are extremly rich, it was my understanding that they would start to get closer to 0 as they learned. Do I need to wait a little longer for them to learn more or is there something wrong here? Like i stated before, im a total noob to this so please bear with me.

[5FDP]

Trims do not have to do anything, they are only reporting back what the engine is doing.

If the trims are rich, there could be several reasons for it. Like a dirty MAF sensor, leaking injectors, leaking fuel pressure regulator, a front o2 sensor that is reading improperly. Rare chance that you have too much fuel pressure too, so it's pushing in more fuel than it thinks it is each time the injector opens.

Could even be the fact that you are running way too cold of thermostat and the engine is not getting hot enough to help completely burn off the fuel. 160-170 at cruising speeds is way too cold in my opinion. I always ran a stock thermostat in my GTP because 190-200 is the sweet spot for coolant temps if you ask me. I always altered the fan settings to prevent the coolant from reaching over 212-215 sitting still and even that is not considered hot by any means.

If you do some check overs and things seem okay, just yank 3-5% from the entire MAF curve and it'll bring those fuel trims from -10-20% way down.

[cobaltssoverbooster]

trims get closer to 0 as you tune the ecu. as stated by 5F, they only report a value so if they stabilize off zero then you have a fueling error in the amount of trims away from zero (in percent)

[Knightmare1981]

Ok, so i'll try cleaning the MAF sensor tomorrow, as im pretty sure i don't have a fuel leak. i'll also grab a thermostat (195*?). Do I need to reset my fuel trims again before scanning? Logic tells me i need to so that it can relearn with the changes but i just want to make sure. Now, after scanning again, if the trims are still high, you said to subtract 3-5%, do i do that to the MAF calibration table (airflow vs. freq.)? and to do that i highlight the whole table and multiply by .97 if i want to subtract 3%, correct?

sorry to be "that" guy, but this whole thing is a little overwhelming. I really appreciate the help tho.

[5FDP]

Resetting the trims is not something you have to do every time. It will learn on it's own and with hardly any real drive time you will see a change straight away if say the MAF was dirty or something along those lines.

Yes a stock thermostat is like 192-195.

Yes, that is the table. You can multiply the table by .97 and it will remove 3%. If you need to do that just do it from 0-7000hz instead and leave the higher Hz range the same. Click the smooth table afterwards to keep the curve nice.

After you get that little bit sorted it's tough to say what you can do from there. Hopefully you run 91+ octane in this car. Knowing the real time air fuel ratio with a wideband o2 sensor and trying to optimize timing with no knock are good things to do/know. You kinda need more boost to make more power, 7-8psi is not going to make much even if fueling and spark timing is dialed in.

[Knightmare1981]

i don't have a wideband as of right now, I will be getting one soon (aem x-series). I run 93 octane at all times, sometimes ill throw a bottle of Torco Accelerator in with a tank of gas. I've done a CAI, and a 3" downpipe w/cats & u-bend delete, and of course the 160* thermostat that was apparently not a good idea, lol. Powerlogs will be the next mod, and then a smaller pulley.

Everything i've read said to get rid of KR before starting to drop pulley sizes, I did not realize how hard this was gonna be to do myself, lol. Once i get my exhaust opened up a little, and get my fuel trims in line, i'll get a wideband and start on tuning out all the KR (so expect to see me begging for some more help), and then we will start talking more about boost, lol.

thx for your help, i really do appreciate it, i would probably start popping pistons without it, lol.

[cobaltssoverbooster]

if you clean it and nothing happens then just check for an intake leak that would be common to both banks.
if there is none then sometimes the ecu is just off. My uncles GXP was off by +7% on the factory tune file and the wot afr i was recording was 10.7.
My yukon that i had this year was getting -15% globaly and the n/a afr was in the same 10.8 range. after fixing both i saw huge gains. sometimes the factory stuff is just close enough to work but not the most efficient.

short story here, if you do all the mechanical checks and its still off then its time to get that wideband installed.

[Knightmare1981]

So I cleaned the MAF sensor, I guess it needed it because it feels like it isn't as sluggish as it was. I haven't changed the thermostat yet due to the crappy weather, but i did pick one up (192*), and will swap it out when I get a nice day. I got antsy and went ahead and lowered my MAF table by 5% up to 7000hz and took it to get some gas and scanned it, I didn't fill up as many cells but the ones that did fill up looks like it didn't help, still reading in the high negatives, maybe a little worse. I guess my question is, what does this indicate? I'll include my last scan (2 scans because it stopped halfway thru), should i put it back to stock and wait until I get a wideband??? And yes, the nearest gas station is about 15 miles away from me, lol.

[cobaltssoverbooster]

i suspect there is a leak in the intake causing issues on both banks equally. did you ever inspect the intake for leaks? smoke test?
if you can say for sure it has no leaks then...
your showing up fat all over the place. i would go to your ve table and multiply the whole thing by .8

[Knightmare1981]

Yes, I visually checked for leaks around the intake and found nothing, all my vacuum lines are good. I will look into a smoke test, and go from there.

I was under the impression that the VE table didn't really matter on these engines (unless the MAF fails)

Should I go ahead and flash the stock MAF table back until I can get a smoke test done?

[cobaltssoverbooster]

The goal is to be 100% sure your not getting unmetered air into the engine. If you can say with 100% certainty that you got no mechanical issues, then you can start tuning.

The ve is a fallback. personally, I disable the maf through tuner software so I can purposely tune the ve in. After it's done I go back and fix any maf discrepancies. To finish it I work my ignition maps at the very end along with adjusting any torque management that I decide is needed.