nskyline34

iTrader: (2)

So started tuning my VE table again because there have been a lot of changes that I've made in my tune over the past year, and just wanted to level set VE and MAF again. (Both were previously done by someone else on a dyno)

I have now taken 25% fuel out of my VE table 2x, and the car never pulls timing, it has gotten a little more responsive, and just driving around it feels fine, but I'm nervous. We all know things run their best before they let go! haha I know that cruising there is no pressure or heat, so things almost never let go, but just want to be safe.

So I followed the guide/link at the bottom of this post, and all was going well, but it wants to push the car to a 14.7 AFR - not 12.6-12.9 like I have set in my PE table. I know VE is a steady state table, but if you push the petal enough to get to PE enable (I think the enable TPS% is like 64% for around the 2,000rpm range), then it will go to 12.68 like I want, but just cruising around logging (1,400 to 3,500 rpm's) it wants to go to 14.7? I feel like this is too lean even for cruising around? The second you get into the throttle it will command 12.6, but I think that for some reason the car should run at about 12.6-12.9 for ALL RPM, and then lean cruise should be what leans it out...or am I wrong?

Thoughts?

Link:
http://michigansnowmobiler.com/hptun...ons%20rev2.pdf

06MonteSS

at part-throttle normal cruise driving, AFR will always be stoich at 14.6 - 14.7.. that's what the pcm uses fuel trims for, to adjust fueling to keep the stoich afr at 14.6 - 14.7 for part-throttle .. normal stuff..

2xLS1

iTrader: (25)

If you want richer cruise A/F you have to run full time open loop.

nskyline34

iTrader: (2)

So basically what you fellers are telling me is that I'm worried over nothing and to keep going. lol That's honestly what I needed, I figured, just wanted to confirm is all!

And I want it to still run in OL/CL hybrid (20% street car still)

Whats your guy's method for hitting the higher RPM cells 4000-6000rpm while doing VE tuning? "steady state" means slow acceleration, so just accelerate slowly into those RPM ranges or...?

Atomic

iTrader: (37)

Normal is 14.6, rich is less than that, and lean is more than that. The closed loop system will use the o2 sensors to force it to always be there. The amount the sensors have to correct the fueling to get it to 14.6 are the fuel trims (long and short term).

Theres really nothing to be gained by not using the closed loop system when cruising unless you really spend some effort in OL leaning it out manually, but thats a lot of trouble. You can set the enrichment criteria pretty low so any time you are doing anything but cruising and idleing you can have it richer.

For the higher rpm stuff I get up to speed and manually drop the shifter down to 3rd or 2nd and slowly use the throttle to get some decent data. The highest I usually go is 4600ish as things tend to get warm up top and part throttle high rpm stuff doesnt need to go to redline as you will never be there.

nskyline34

iTrader: (2)

Correct I agree there is nothing to be gained by not being in CL when cruising, but I was noticing that the car was guzzling fuel - STFT's (LTFT's disabled) were reading high -20's always. So that's why I decided to go back and redo the VE and MAF tables again since I've fiddled with the tune so much. I guess the CL enrichment table for doing the VE and MAF is set to 1.00, but then once you go back to CL (for normal stuff - not tuning) then you set this to like 1.08 or whatever you prefer, so it will richen it up a little bit.

Like I said, car runs great, I just wanted to make sure that basically under 3000 rpm or so it is ok to be at 14.7:1 AFR. once you get on the skinny petal then it richens right up to 12.6-12.9, so I wasnt worried about that. Just making sure.

Thanks for the help fellas!

dw456post

Are you failing the maf and setting P0101-102-103 to mil on first error when you are trying to correct the ve table? Cot off? Dfco off?

nskyline34

iTrader: (2)

Yup to all 3.

dw456post

Sounds like you have it correct. Don't log the MAF in channels while you are tuning ve.
The narrowbands will always try to get the afr to 14.7 even if you set the maf to 1.08

nskyline34

iTrader: (2)

Right now CL is set to 1, and I was going to leave it like that while doing MAF too. That's correct isn't it?

Darth_V8r

iTrader: (4)

Just in case - if you're running a 102 throttle, I usually drop the TPS in the PE enable tables by multiplying by 0.6. The throttle body has double the area, so the engine really loads up at less throttle vs stock.

Otherwise, agree with other comments above. Just keep going until you're right at 14.7

nskyline34

iTrader: (2)

Ok thank you - car just has a 90mm in it - I updated the scaler. Cannot believe how rich this damn thing was - no wonder if felt like it was drowning and was guzzling fuel.

Darth_V8r

iTrader: (4)

I bet every time you adjust it it just feels snappier and snappier

nskyline34

iTrader: (2)

basically! I was always amazed at how gutless it felt under 2500 - always assumed it was because I have 17* overlap lol definitely getting better