Thread: Ltft show rich but wideband and stft say otherwise

Not sure what's going on and my tuner is having no luck keeping this thing stable. It will run good with a new tune then it will go rich again. The stft are from -3 to +3 cruising around and will occasionally go richer on decel. The ltft go between -13 and -21 but will lean up on decel as the stft richer up by roughly the same. The wideband is in the 14's most of the time but will head towards the 11's under accel and in the 12's in decel. This has been this way since I got the motor and now I'm running sd headers, gen v with a 3.5 pulley. I've tested for leaks and nothing shows up and my vacuum is in the low 20's.

Anyone, I cans get it out of closed loop as well.

The tuners been doing it for ten years +. No matter what, he gets the fuelling spot on and then a couple drives later, it's back to being extremely rich again. This morning going to work, it was rich like normal, 12 hrs later and on my way home the ltft's were -7ish and the stft's were -3 to +3 and were balancing each other out. An hour later I seen ltft's in the 30's at idle. This is all in closed loop, but going down the long hill in town I drop it down into second to keep the speed rather than ride the breaks and when it's like that, it goes into open loop. I hit the throttle and it's back in closed and back and forth. This has more mood swings than the wife.

Originally Posted by darkhorizon

your "tuner" is making the most obvious mistake then... you are not "tuning" anything if you let the car run in closed loop.. it "tunes" the car for you so if its doing it wrong then its the "tuners" fault for letting it.

a 3800 in closed loop with a "custom tune" on it, is not going to do anything different from a stock tuned car. Period.

He's trying to tune it in open but the bugger is staying in closed.

Originally Posted by darkhorizon

Unplug the o2 sensor then

Yeah we had talked about that. But I want to see if I can get this problem figured out. Cause it does go into open when going down a hill coasting in second gear. And we have had it there before, not sure what's changed, haven't touched anything.