TheMagikMan

I don't have a wideband at the moment and lack the income while on the job hunt after college to get one, so I'm looking for examples of the fuel tables for people's PE modes as well as the corresponding AFRs that you get with those tables to see if I'm trending way rich (which I can smell that I am). I just want to make sure that I don't lean it out too far in the pursuit of a placebo "I can FEEL extra power!" that isn't there.

I did at one point develop a mathematical formula to take load values from a WOT datalog to generate a rough torque curve and then map my enrichment against the curve, adding fuel around the torque peak and then pulling it as it lost torque, but then I realized that might be useless because you want more torque up top, not just make the same curve taller.

dabomb6608

iTrader: (3)

Get a wideband. No two builds are the same especially when factoring weather conditions and the effects they can have on AFR.

How can you effectively smell your exhaust while moving and in PE? Exhaust plumbed into the cabin?

Orr89RocZ

iTrader: (20)

I guess it depends on the setup and how quickly the maf maxes out.

I admit i never got into the math behind the code in how it calculates air fuel from all the parameters that influence it. And depending on which base bin you use, it seems to vary anyway.

id have to open up a couple tunes but i know my 383 hsr that dyno’d around 400 whp had PE enrichment vs rpm as high as 70-80% and it followed the torque curve of the engine almost exactly. PE % Tapering off after peak torque then slightly rising again as it approached peak hp. Which was 6250-6400. Maf was maxed out at like 3800-4000 ish rpm i think.

tuning open loop with wideband and using the pe enrichment vs rpm was my fav way to do wot tuning. I tried not to adjust maf if i could avoid it. Part throttle and idle i did play with maf tables.

???

iTrader: (5)

how far from stock setup are you?

seems like forever ago before wideband were a thing everyone could buy. if the engine was pretty stock, you could pull some timing, disable pe mode and tune the ve table at 14.7 with the narrow bands. and then again as long as your engine was say just bolt ons you could turn pe mode back on and it would be pretty close.

you could try something like that. Just watch knock.


funny thing I had a old 91 rodoe with the Isuzu 4cyl before they put gm motors in them. I happened to have a old lm1 wide band and hooked it up out of curiosity and that thing had no pe mode. it always ran 14.5 ish no matter at idle, decel or wot. I guess when you make maybe 75hp who cares haha.

TheMagikMan

I understand that but I also can't afford the $200 that I would need to drop given the total lack of income. I have a bad clamp precat on the y pipe that I've been meaning to fix

TheMagikMan

Pretty damn far. It's a swapped motor. Stock was a 305. This one is a 355 with heads off a 69 Z28, edelbrock base and SLP runners. Intake, runners, and plenum are port matched and mildly siamesed at the top with a Comp Cams XR269HR grind Xtreme Energy roller cam at 10:1 compression. All fueled by a wet of Accel 30lb injectors.

TheMagikMan

That sounds just like the way I would like to do it but unfortunately the lack of a wideband kills WOT tuning. I have for the most part left alone the VE tables up top, relying on the PE values. I would love to take a look at those bins. Do you leave your temperature based enrichment at zero and tune only with the RPM table? I don't know how they stack so I'm not sure what my total enrichment is. My MAF doesn't seem like it does quite max out anywhere though. Not sure I'm running that much power!

Orr89RocZ

iTrader: (20)

I have left the temp corrections mostly stock i think. Id have to look. You can use them to help offset the cold start/running til it heats up. Typically need the extra fuel.

you can use narrow band at wot, try getting it close to 880-900 mv. Usually ballpark wot afr until you get a wideband. But if you have any exhaust leaks or what not it may skew readings. Might not tho

dabomb6608

iTrader: (3)

I can tell you from running my setup with no cat that a 14.7 afr will still smell rich.

Jobs are a penny a dozen these days. You will be time and money ahead fixing that exhaust leak and getting a wideband. Sure a good tuner can probably get it close without one, but to jump into the tuning world without one is just asking to chase your tail for months. Wasting gallons of fuel ($$$) for testing along the way.

RBob

iTrader: (1)

How did we ever tune before inexpensive WBs were ever available??? Something about looking/reading spark plugs? Sound of the engine?

And yes, you are welcome for inexpensive WB setups, but it is nothing more then another tool in the box.

RBob.

dabomb6608

iTrader: (3)

This is true. It is possible. But for a beginner at tuning that tool is invaluable.

Don't take what I said as me saying it isn't possible. All I am trying to say is a majority of the time the labor and money spent trying to do it without one could easily be offset with just purchasing the tool from the beginning, especially when adding the experience of the tuner into the equation. Time is money and fuel is also money (considerably more money than it was before inexpensive WBs).

TheMagikMan

Well I daily drive the car and I like to have some fun so I'll be wasting gallons of fuel anyway so I'll keep trying new tunes.

TheMagikMan

I'll give that a try! Thank you

ULTM8Z

There's a huge convenience aspect to it as well, especially with an Ostrich or EBL... do a hard pull, note the AFR, pull over and make a change to the tune, upload and then make another pull. Doesnt get any easier than that.

SbFormula

Some people datalog WOT and look at O2 voltage. Here's a gross approximation:

830 mv = 13.0:1
880 mv = 12.5:1
930 mv = 12.0:1

That could help you to get in the ball park. You may want to keep it between 12.0-12.5 until you get to a chassis dyno

This is not exact and absolutely not a recommendation. I use WB with chassis dyno.