Tuning LTFT's...

[GTPNoga]

This is a great thread it has helped me just by reading it. When I paste from my scans to the MAF table my “curve” is not smooth it has dips and spikes. Do I smooth them by hand or do I upload the flash and keep with this method of pasting until the curve becomes smooth? BTW I am using the same histogram that was on the first page of this thread.
Thanks
Joe

[Bandit gs]

If your tuning with a WB you're ok, mine looks like the rockys. If i get a really crazy spike i'll hand smooth it.

[nitrousgp]

Quick question. Are LTFTs significant during WOT?

[GTPNoga]

I don't have a WB yet. Soon but not soon enough.

[5_Liter_Eater]

Quick question. Are LTFTs significant during WOT?

If they're positive then yes. If you are seeing positive LTFTs in PE cells it's adding that much more fuel to the mix. So if you're commanding 1.225 (12:1) and you have a +5 LTFT it will add 5% to that making it 1.286 (11.4:1).

If the LTFT is negative or zero then it is neither adding nor removing fuel in PE.

[Junior1683]

whats a good wideband to get?

[5_Liter_Eater]

Can't help you there. I'm questioning the accuracy of my AEM. I would recommend one that can be free air calibrated. There are more than a few threads with everyone's opinions on WB's.

[Junior1683]

im waiting on my new 3.2 pulley to show up so i can put that on and see where i sit with my KR..

is there any side effects to how i tune out all that KR? like will i lose power from it? also, can i increase the numbers if i dont have KR incase i tuned them too low with the copy/paste subtract deal?

[5_Liter_Eater]

If you're planning on installing a new pulley I wouldn't bother fine tuning with your existing pulley.

Side effects? Tune to max timing until KR, then back off a few degrees. The only way better than that to tune timing is throwing the car on a load generating dyno and tune each cell to max HP and torque by playing with the timing and AFR, again, in each cell....Not really feasible.

[Raptor285]

whats a good wideband to get?

PLX, can be had on ebay for about $250 with a gauge...

Sorry about the info, but that's the way i was taught to tune, give the car what it wants...however I am probably going to start tuning with histograms.

I was told using the histos were more trouble than they are worth , but I'm definitely going to give them a try...WB is next on my list of mods as well.

All this time w/ a WB I could be getting better mileage and a better idle

[MMGT1]

Bandit made a comment above that has me thinking. His MAF curve is very bumpy and mine is smooth. Would you think that the MAF curve being smooth could cause me issues? When I scan MAF error % I'm 0 or -1 plotting the WB through the EGR. I'm dealing with a hesitation that I just can't find!

[Junior1683]

my maf curve is smooth and im around -.7 to 2.3, the 2.3 is when im off the gas or at idle..

[LazMan]

Tuning with comptuer logging and sutff has come a LONG way in the last 10 years. Old-school tuning (giving the car what it wants) is no longer the way to go.

Trust the histograms. :-)

[Raptor285]

Tuning with comptuer logging and sutff has come a LONG way in the last 10 years. Old-school tuning (giving the car what it wants) is no longer the way to go.

Trust the histograms. :-)

I'm going to try the histos for sure when I get the WB, then it's on!

[Junior1683]

i put the smaller pulley on and only see small blips of knock!!!

[zacknhs]

first off even small blips of KR is bad, for the engine and for power.

Question:
i saw that some one said use multiply % half. and it's in russ k's maf tunning write up. what dose that mean. i understand what it dose but why?

i just got my Wide band and it seems like every thing i do makes my tune worse.
My commanded AFR will be 14.7 and my wide band will read either way rich all the time or way lean.
here is a scan.

[muayyadf1]

Get a wide band. You still have little to no idea about whats going on under WOT.

Can you tell why he can't use the stock o2 sensors and keep their values as close as to 890 mA ?


Thanks for your effort

[jmoody66]

Im trying to smooth out my ve table. Could anyone tell me if they think this will be ok to load or am I going to push this into the lean zone. Its the file named jerry smoothed. This is an STS running 7lbs on an 02 Z06.
I have had some issues transitioning into boost but then it gets going BUT if you continue to push hard like into the 80 to 90 mph range it seems as if it is stumbling ever so slightly.....kinda hard to explain but it does not want to keep on steam rollin ahead. You can see where Im having issues transitioning into boost on my scan...the WOT run I have not done.
Heres a copy of my scan, tune and the smoothing I want to add.
Any input would be helpful.
Thanks,
Jerry

[5_Liter_Eater]

Can you tell why he can't use the stock o2 sensors and keep their values as close as to 890 mA ?


Thanks for your effort

Because the narrow bands are not accurate outside of measuring stoich. I have logs where my WB is reporting 13:1 and my narrow bands report ~890's but then I have logs where my WB reports 13:1 and my narrow bands are nowhere near 890.

The 890 mV rule of thumb is only good to sanity check a tune but not accurate enough to tell 12.5:1 from 13:1 from 13.5:1.

[Shazbot]

just an update!

been workin on the huge KR problem ive had and im almost ready to drop another pulley size!! at WOT i was seeing 5-6* of knock and now im seeing small blips of it!!

im gonna do some more tunning later this week and see what i got left!!

any ideas what i should tune next to try to gain as much power as i can? timing? fuel? any ideas!

I hope someone has told you at some point that pulling timing to eliminate KR just so you can drop a pulley size is bad. The timing your running DIRECTLY dictates how much power your making. If you run 18* of timing and pull 5* of it due to KR, than drop a pulley size you are essentially at the same point in which you started(your horsepower gains are negated by lower timing). If the entire GTP community could just pull timing and drop pulleys... life would be great! Pulling timing is an interim solution for many things and importantly for the charged folks... KR.

The general rule for dropping pulleys is DO NOT DO IT unless you can run your current pulley at high timing without much OR ANY KR. Running the stock 3.8" pulley with 20* of timing(no KR) will be the same if not better than running a 3.4" pulley with 14* or 15*(no KR) of timing.

The key is to maximize your timing and minimize KR before dropping a pulley. This can be done through tuning or more so through major upgrades, such as intercoolers, cams and even rockers not to mention the numerous assortment of bolt-ons.

I can advise all day long on upgrades and the effects of them (GTP only), feel free to pick my brain in those regards. I am just new to the tuning aspect of it.