tuning part throttle with a damn wideband

[bpm]

hey guys, ive been tuning for a few years (mine and customers in sd) using the stfts for everything bar WOT. WOT was checked with a my wego wideband and adjusted if necessary via the VE table, but it was usually spot on commanded after a stft tune. ltfts i turn off. ive had an enhanced io for a while and i thought, shit, i better get with the times and use this interface for a wideband. had nothing but trouble since. i bought an lm1 because the display was flaking out on the wego occasionally and reading .1 and i couldnt get the wego to work with hpt properly (got it working now though), did a tune on my own ute which is cammed and turbod. got it spot on in open loop with the lm1. turned the st trims back on and its pulling like -8 to -12 everywhere.

after reading all that, i guess what im trying to say is, is there really anything wrong with tuning the part throttle with the narrow band 02s? and are lm1s shit?

btw i have swapped in a new set of NB 02s and checked the wot afrs with a dyno wideband and thet are ok. the dyno wideband shows 13.5-6 at part throttle.

[Russ K]

Keep in mind that the evap purge valve stays closed in open loop. In closed loop when the purge valve opens,
the fuel trims will go negative to compensate for the extra fuel vapours.

Russ Kemp

[5_Liter_Eater]

So what I'm hearing is that you tuned OL with the WB spot on, enabled closed loop and trims went negative. You replaced the narrow bands and no change, big negative FT's. You dynoed with another WB and the WOT's are the same as you dialed in with your WB but the dyno WB shows CL part throttle rich at ~13.5:1. Was that with the fuel trims enabled?

[bpm]

the trims were disabled on the dyno run. wot afrs seem good, part throttles are way rich, but the lm1 shows 14.7.

[5_Liter_Eater]

True or False:

- Part throttle was tuned to 14.7 in OL with the LM1.
- Part throttle is shown rich (~13.5) by the LM1 when in CL after FT's drift to ~-10.
- Two different WB's read the same at WOT and part throttle.

The reason for the questions is myself and others who try to tune exclusively with the WB run into similar behavior as well. I put it in OL MAF, tune it dead nuts on in OL. Put it back in CL and trims go whacky (can't remember which way) and the WB shows ~15.5. This is making me doubt my WB but the other thought is that long tube headers have thrown off the NB calibration. You have had the luxury of swapping out NB O2's and having several different WB's. I guess we can conclude that since two different WB's are reading the same that the NB's are out of whack because of the mods.

[bpm]

True or False:

- Part throttle was tuned to 14.7 in OL with the LM1.
- Part throttle is shown rich (~13.5) by the LM1 when in CL after FT's drift to ~-10.
- Two different WB's read the same at WOT and part throttle.

The reason for the questions is myself and others who try to tune exclusively with the WB run into similar behavior as well. I put it in OL MAF, tune it dead nuts on in OL. Put it back in CL and trims go whacky (can't remember which way) and the WB shows ~15.5. This is making me doubt my WB but the other thought is that long tube headers have thrown off the NB calibration. You have had the luxury of swapping out NB O2's and having several different WB's. I guess we can conclude that since two different WB's are reading the same that the NB's are out of whack because of the mods.

T
F LM1 shows its lean in closd loop like 15.5-8
F LM1 shows 14.7 in open loop dyno wideband shows 13.5-6. WOT is very similar between the two. im doubting the lm1 bigtime.

[Dirty Howie]

Bill

Another 15.5-15.8 in CL instead of stoich .......


DH