urdone

iTrader: (1)

Well guys i almost finish dialing the VE table on my 2004 5.3 and i want to leave it in speed density.
Right now i have the LTFT and the STFT disable, my airfuel error is at 2% at cruise and WOT.

I was searching around in Hptuners forum and looking at files, and i see that some of the tunes have fail MAF running in open loop disabling the LTFT but have the STFT enable. My question is what is the difference if i run open loop with LTFT and STFT disabled and running open loop with LTFT disabled and STFT enable?

Heres my file is a 2004 5.3 silverado with a 224/224 cam and headers with a 3200 converter.
I still need some smoothing on the VE table.

kelsey_canard

iTrader: (5)

I am also interested in this. I want to say I read that ltfts carry over when you are in power enrichment, but I am not positive. I personally would stay in closed loop if possible. I ran open loop for a while and didn't really care for it much.

oakley6575

iTrader: (5)

If you turn either STFT or LTFT on, you are not in open loop. Open loop is when the 02's are inactive and don't control fueling. I personally run closed loop but keep the LTFT's off. Kelsey is correct when he said LTFT carry over when PE is activated. If you tune the VE correctly, there really isn't a point to have LTFT active since the tune will be close to perfect. Plus you will never be able to hit the correct AFR or lambda values that you shoot for under WOT.

03klugss

iTrader: (1)

Well put!! LTFTs are a pain in the *** during the tuning process if one is trying to dial in their VE and or MAF tables in closed loop. If I am tuning in closed loop I've always disabled LTFTs and just dial everything in using STFTs, makes for a quicker process and as stated if everything is done correctly tune should be spot on with the short terms. Would be able to re enable LTFTs and they should fall right in line.

slow67

iTrader: (2)

X4, leave LTFTs off, only STFTs.

urdone

iTrader: (1)

So if i tune my truck with the wideband and the STFT on and fail the MAF thats close loop?

I got confuse when i start it searching and looking at files with the MAF fail and STFT on.
I always tune my truck on open loop with the LTFT and STFT off and fail MAF.

BLK02WS6

iTrader: (2)

When you are in open loop, there is no fueling correction based on O2 sensor feedback - that includes no fueling correction by STFTs or LTFTs. There are a couple of ways to put it in open loop (raise the closed loop temp enable table to the max or unplug one/both sensor 1 O2 sensors).
You can also disable the LTFTs seperately.

You should always tune in open loop using a wideband to correct your fueling (VE and/or MAF tables). And, you should always clear the learned LTFTs before starting to tune.
After you have corrected your tables, you can put it back in closed loop and it will correct by STFTs and LTFTs (if you enable them). One thing to note - LTFTs will only carry over to power enrichment if you are lean (+LTFTs) when you entered power enrichment. If you are rich (-LTFTs), they zero out when you enter power enrichment.
The only reason I would disable LTFTs is if you have exhaust leaks skewing the O2 sensor feedback. Otherwise, why not use the built in correction to get the best fuel mileage?

When you fail or disconnect the MAF, and run only on the VE table, that is speed density - nothing to do with open or closed loop.

Also note - all of the above applied to LS1b PCMs (yours) - E38s are somewhat different than the above explanation (STFTs and LTFTs are different in how they operate in the E38 controller).

swift700

iTrader: (3)

Good info, BLK02WS6. That's what this forum is all about.

urdone

iTrader: (1)

Thanks BLK02WS6, like swift007 say this is all about helping each other.

BLK02WS6

iTrader: (2)

Glad you found it helpful - I try to help as much as time lets me!