Mega confused

[keeley75]

Dear All, can anyone shed some light on my VE table..

3.9 V8 on Autobox

H180 cam. Everything else standard  except skimmed heads.

Standard 3.9 injectors

Tunerstudio

 Innovate LC2 wideband. This is the table after using the auto tune facility.

The vehicle starts, idles and drives very well. 

 

As you can see the values appear odd. I would expect there to be a gradual rise. What I get at 1200rpm is a fluctuation from 82 to 168. Is this normal.

Also can you confirm the values are just numbers and do not relate to the percentage of ‘fuel load’.

I have scoured the forums and most appear to use megatune where it uses volumetric efficiency Kpa vs rpm.

I apologise if I’m being a right numpty here. I’ve read so much my head hurts. Hoping for some guidance.

 

 

[FridgeFreezer]

Doesn't look right to me - I'd question if the sensor reading is actually correct and true - a small exhaust leak can throw it off easily.

Also if your accel enrichment is too rich it can throw a bucket of unburnt fuel down the pipe which smothers the sensor and reads lean, same with a misfire, burning oil or leaking coolant etc.

Does the rest of the table stay "right" when you use auto-tune? What does your target AFR table look like?

[Bowie69]

I had this, think I put it down to some of the above, acceleration enrichment, exhaust leak.

 

[keeley75]

Wow thanks for the quick reply.

Acceleration enrichment. At the moment I’ve not done much with it. It hesitates ever so slighty and picks up. It’s on the todo list.

AFR is here, It’s from this forum. My previous AFR was 14.7 everywhere.

 

just to cover Your  experience and knowledge.

It doesn't burn oil, it’s no losing water internally. No misfire.

the rest of the table tunes fine with the odd change here and there.

In the interim should I manually correct some of the cells. Play with the AE and then have another go.?

Oh and should the values go- above 100.

Again thanks for your time.

 

[keeley75]

25 minutes ago, Bowie69 said:

I had this, think I put it down to some of the above, acceleration enrichment, exhaust leak.

 

No exhaust leaks.

I was under the impression not to tinker with `AE until the map was done. 

[Bowie69]

The stumble you have, caused by AE being wrong, is quite likely a misfire.

[keeley75]

Guys thanks for the reply.

can I confirm then.

1. AE is incorrect and it’s causing a misfire.

2. The cells shouldn’t go above 100

3. Set AE so it doesn’t activate and retune these cells so the VE table is correct before applying AE

4. Should I manually adjust the spikes in the table first ?

Thanks in advance 

Edited April 21, 2020 by keeley75

[Bowie69]

1) think so

2) yes, assuming your required fuel setting is correct for injectors . VE is volumetric efficiency, without forced induction it is impossible to get above 100%.

3) no, you need to tweak AE so it fixes the stumble now, so you can tune the cells without a glut of either fuel or oxygen going down the pipes. Once tweaked, then try tuning again.

4) yes, for sure. To be honest there is nothing wrong with manually adjusting a fuel table at all, especially at this point, because the engine spends only a fraction of a second in those cells.

[FridgeFreezer]

In TunerStudio you can select those cells and (I think) right-click and lock them from being auto-tuned... but  if you have this stumble/misfire you're potentially not getting the true picture elsewhere on the map either.

You can twiddle with AE any time you like although it's easier to get the map dialled in somewhat before moving on to the AE and other stuff as everything affects everything else - if your map is very rich you need less AE because one is added to the other. It's a rule of thumb that helps newcomers avoid chasing their tails round in a circle. Once you're down to only making small tweaks it matters less and you can fine tune things as much as you like.

The part of the map you're looking at, as Bowie says, is only ever active briefly when you put your foot down hence why it's ended up richened up to compensate for AE. If the rest of the map is pretty close you can tweak it in by eye - or indeed, TS can do it for you;

If you select the column of cells in the 600rpm end from 100 to 70 kPa, across to the 2300rpm column, the button with the three lines (≡) just under your mouse pointer in the 1st pic will smooth those cells left-to-right between the two sets of values. I use that a lot when I get these sorts of quirks of auto-tune.

[keeley75]

Gentlemen.

You have got me in the right direction and found the issue.

AE was the culprit. TunerStudio had AE TPS set to 100%. With No reference to VE. Think thats the way to explain it. I changed the ratio to 50:50 and it allowed subtle but noticeable changes to the off idle stumble. Flattening out the TPS graph has fixed the hole when you tread lightly on the pedal.

With this change it's also no longer dumping loads of fuel in these cells causing this erratic table.

The off idle drive is stronger and smoother

I owe you both a Pint.

 

Edited April 21, 2020 by keeley75

[FridgeFreezer]

Excellent, glad you got it sorted!

AE is tricky to get bang-on, and the TPS/MAP/VE balance can help in a bouncy old Land Rover, I only discovered a problem with mine originally because I was driving at night at noticed every bump in the road lit up the accel LED on the front of the ECU as my foot bounced on the pedal

[Bowie69]

Very pleased

You now have a four legged stool, careful how much you cut off each leg or it will rock