I've been working on getting my data logging for my LTFT and STFT but as I've been looking at my old tune, I've come to discover some oddities about it that concern me.

On examination of my Primary VE and my dyno sheets, there is a correlation between a dip in the VE setting and a dip in my dyno. I've compared it to a similarly modded 2000 camaro with idential cam, intake, exhaust save for his y-pipe and my true dual setup.

I have cats on the car and the AFR was taken at the tailpipe so I'm pretty sure I can lean it out a bit. Getting on it at WOT on the highway will let out a bit of smoke that's not oil. The soot build up on my tail pipes are a testament to that.

Here's the dyno pic about 3 months ago. Tune was done last year and yielded a dead similar hp/torque curve, just higher.


Here's a 2nd dyno pic on another dyno. No AFR.


Here's the comparison between my VE table and the similar modded car's VE table.


Here's my analysis. The low setting of the VE table at 3200 at WOT is what causes the dip at 3500.

Things I would like to do.

1) I fix the odd setting to a similar VE number like the 2k Camaro.

2) I can run the 2k camaro's Primary VE table safely and log LTFT and STFT to see if it's on or needs more tweaking over time.

3) I just run LTFT and STFT logging and come up with my own LTFT.

4) Since I'm getting 12.7 AFR after the cats and the 2k camaro gets away with 1.250 enrichment across the board, I can back off from my 1.300 enrichment and still be below 13. Wideband is coming but in the meantime, I'd like to not have to clean carbon off the tailpipe every WOT run. I'm thinking 1.28 or even 1.27 would be safe for Power enrichment. When I dyno tuned this the first time, we started at 1.26 and gained only 6hp over stock 1.25 and moving it up to 1.3 did nada for the AFR from the tailpipe. Cats have been known to lean up as much as a point for AFR.

5) Get it on the dyno use the tail AFR and lean it up that way. Aim for a 13.5 instead of a 12.7?

 

I have never seen a VE table that looks like that. All of mine
and all I've seen, are 2-digit numbers on a percent scale.
I wouldn't expect the car to even run with that table unless
something else is whacked to compensate, or the display is
somehow off-normal-basis.

You want something lower than 13:1 at WOT for motor safety
and you'd like to arrive at it by performance based data
logging as well as having a wideband monitoring the real
vs the commanded fueling.

Don't fixate on the carbon, it's not telling you anything. It
shows up regardless of state-of-tune, it's the only output
of the motor that has no way to evaporate so it builds up
over time.

 

That VE table is set up to compare 2 different VE tables, so yeah all of mine are 2 digits like this



I was doing the LTFT logging, I disconnected the MAF, copied high to low, used those values for my VE Table, reset the LTFT via resetting the PCM BAT and IGN fuses and drove around. What I got surprised me, only in the low rpm, low throttle 1200-1800 range did I see double digit LTFT, like -11 at most. Everything else was between -5 and 5. I'm following the guide but I'm wondering if I should only change the ones in the double digits and pretty much accept the rest of the histogram as ideal -5 to +5 as what the doc says to go for.

 

Having fun Slade.

Reset trims from the scanner much easier. I'll see you tomorrow and we can do that.

Did you disable the LTFT's for VE tuning yet?

 

It's pretty tedious stuff, but I think I'm starting to get the hang of it.

First time I did LTFT logging I thought I saved the data only to try to open it and find squat! what a waste of an hour of driving. Oh well, I'm surprised how bang on the VE was, but some ares still need some work but I think I'll have it for the most part by tomorrow. I'm going to see if I can book some dyno time with Cdn Perf to mess with the WOT tuning and to see if I managed to pick up any HP with the clean up of the VE.

 

You need to add the LTFT to the STFT to get what the corection is. Some times that will make it Big.

 

I've been adding STFT and LTFT, I will teach the car over the next few days with some driving then do a log to see where I stand.

 

you are making these changes in the secondary VE table with the MAF being failed out, right?

 

MAF is unplugged, though I forgot to disable DFCO and PE so I reset the VE back to previous and am starting again. Also detected a bit of knock in the upper rpm while running, glad I'm not doing any WOT bursts. The good news is that even with this kind of spirited driving, I'm getting better mileage thanks to the small fuel economy tips I got off the HP tuners site, though I won't know the full extent of benefit until I get these VE tables dialed in right over the week or so.

 

you're on track. I tuned mine with the same method and it worked very well. I had to touch up my MAF curve after I reconnected everything and got out of SD mode though.

 

I'm hoping to get more driving in but I kind of want it to coincide with having to go someplace. Also weather is **** from time to time... ok it's sucked lately more rain than sun. I think it's good to get some readings in rain too as that will help create a more balanced VE table that isn't biased towards hot florida style weather. Also I think keeping the MAF in the long run keeps that safe too as opposed to always running with a single tune when the climate here swings wild.

 

Looks like your on the right track slade. When I was trying to get my LTFT's and STFT's right they were WAY out of whack at first. Ive got mine all 0 to +3 or -3 depending on the day which I am sure when it gets cold outside im going to have to re tune. My fuel economy cruising around and on the highway is A LOT better now