constant negative ltft's

[gs jason]

What would cause this? Gas mileage has gone way down and the car feels sluggish.

[gn2beatu]

You might want to post more info. Like have you changed anything in your tune lately? Differant gas? Are you getting misfires or did you log for misfires? Any other changes on the vehicle, like new O2, MAP or MAF. Tell us when it started happening and anything related to it.

Im seeing them as high as -14 in the middle RPM range, but not all over, in fact some areas have little to no long term trim, unless you reset the trims right before the log. What vehicle is this off of? Since down low hasnt changed at all 700-800rpm, did you do a differant CAI, exhaust or headers. More info needed.

[GeoJB]

X2, more car info needed.

It looks to me like your O2 sens is lazy, mostly looks like a sign wave, not too much for sharp spikes that should be seen.

Do you have a cat?
Rear O2 sens?

You have done a few MAF tunings.
But not any VE tuning. (despite the controversy) Its there for a reason.

You also changed the injector settings, Why?

Don't forget we are getting into winter and the gas formulation is/has changed.......sucks!

Are you on the RegalGS.org board?

[gs jason]

I did switch to 91 form 94 octane. I thought it would run leaner with less octane?

I'll try to explain what I've done. Mine is a 2000 Regal.

I had Gary tuning this car a couple years ago. At that time I had headers, 3" exhaust and a 3.5 pulley. When I demodded Gary was gone so I bought the tuner and returned most settings to stock, but using a 2002 regal file. Right now I just have cai and a 3" catted dp with a rear o2.

I've done a few maf tunes but it should be at the stock settings now, stock for an 02 Regal. Maybe thats the problem? VE was close so I left it alone, could be wrong here though, anyways I left it stock. AFAIK the injector settings are stock, but again I'm using 2002 Regal settings. Can I use a 2000 Grand Prix file?

No misfires, well number 4 at idle sometimes but not while driving.

I just found a 2000 regal file that claims to be stock and there are quite a few differences between the 02 file I am using. Primary VE vs RPM vs MAP is alot different.

I think the problem is me, lol.

[PSYKOSTEVO]

was that your problem afterall?

[gs jason]

I haven't really had much time to figure it out. I've got a new o2 sensor to put in. Once I get that in I'm gonna start with a stock file and see what I get.

[MMGT1]

After the O2 repair, if it is still doing it, check out that dam crank sensor. Lately I have seen far too many GM V6's with the crank sensor gone bad on them, and none of them are throwing codes for it! May see a MAF code here and there but its not the MAF. The lazy O2 and the miss at idle is exactly what mine did for two years before we changed the crankk sensor and fixed it

[gn2beatu]

I bet when he goes back to stock that fixes it. Differant years will have differant MAF tables. My 97 GS had two 90 degree bends in the intake tube, and my 2000 had more of a 45 degree bend. Lots of things affect the MAF tables. If you put an aftermarket air filter set up, that will affect it. My suggestion is to do what you said, go back to stock to start, then touch up the VE and MAF tables.