2 bar os

[LS ROB]

As some of you know, I've been working on VVE for a long time and keep getting those little jerks/lean spikes while cruising. I have seen where applying the 2 bar os seems to help with fixing that. What does the 2 bar upgrade actually do? Do you think this is more of a "needs more tuning" issue or possibly need the 2 bar upgrade? The VVE still needs work I'm sure but I feel like no matter how smooth the table is, the car is still going to stumble. The car is starting to feel pretty good, pulls hard, getting roughly 18.9 mpg, and cruises ok besides the stumble. Anyone have suggestions? tsr.hpldaily tune vve.hpt

Thanks

[mememe123]

What ECM ?
And also, something that was helpful to me in street tuning... Do like 20-30 min logs in 3rd or 4th gear only, "past idle to WOT", and do idle separate.

[LS ROB]

What ECM ?
And also, something that was helpful to me in street tuning... Do like 20-30 min logs in 3rd or 4th gear only, "past idle to WOT", and do idle separate.

ECM is an e38.

[mememe123]

Have you done smoothing by hand or the whole table after applying corrections ?I had "jerk/stumble" at 62mph
And smoothing+re-logging fixed that issue.
If you look at VVE graph in 3d, essentially, all the sharp edges are what's causing that (going rich to lean suddenly).
I'm not a professional tuner by any means, just shearing my 2c, and maybe this bump will bring in more knowledgeable people.

[LS ROB]

I've tried hand smoothing, smoothing large sections, small sections, the whole table. I've also tried hand selecting only the lean areas and adding fuel and smoothing. The best I have gotten it was with a 45 minute drive. I've also tried one tune per day, so that I know that rich after flash wasn't an issue. I have a suspicion that my wideband may be reading slightly off (.03ish) Not sure how to fix that as it is the AEM 03-0334 obd serial port type. Like I said, the car pulls like a freight train; but at cruise, it's like it has a case of the hiccups. I have minimized this from my previous tunes but still feeling that small little hiccup that needs to disappear.

[07GTS]

best thing about the 2 bar is its a proper VE table so no calculations just cell by cell adjustment, also u can adjust fueling per boost not just PE

[Alvin]

Aren't you working on a MAF/VVE tune.. If your MAF is enabled and running you will not experience the VVE bug that SOME not ALL speed density Gen 4 cars have.

[LS ROB]

Aren't you working on a MAF/VVE tune.. If your MAF is enabled and running you will not experience the VVE bug that SOME not ALL speed density Gen 4 cars have.

Alvin, you are correct. It is a blended tune. I have the MAF set to take over at 2800rpm so the VVE table is primarily referenced up to that point. Are you thinking this is a case of the VVE needing more tuning?

Thanks!

[LS ROB]

nd.hpldaily tune vve.hpt attached are the current tune and most recent log to show the issue. I'm thinking that there may be a discrepancy with my wideband or my o2 sensors. I'd love to be able to paste percent half but that throws my calcs off. As of now, im comparing my VVE table against my WB cell by cell so if the WB shows lean AND the cell shows lean, ill add fuel. It's a real pain but im not sure what is going on. If you look at the WB error, it shows a lean correction within 1 mostly, but if you look at the fuel trims, they're all over the place. Anyone have any input or suggestions?

[JasonHSV]

In your current tune you have the narrowbands in control of the fuel adjustment and your wideband is reading the results of that adjustment, so the data is as you would expect.

Everyone has their own thoughts on this, but I always use the factory narrow band sensors for closed loop fuel adjustments and save the wideband for WOT tuning. When you're finished tuning and go back to closed loop, the narrow band will take control anyway and they are extremely accurate at lambda 1.

[LS ROB]

In your current tune you have the narrowbands in control of the fuel adjustment and your wideband is reading the results of that adjustment, so the data is as you would expect.

Everyone has their own thoughts on this, but I always use the factory narrow band sensors for closed loop fuel adjustments and save the wideband for WOT tuning. When you're finished tuning and go back to closed loop, the narrow band will take control anyway and they are extremely accurate at lambda 1.

Jason, why do the Fuel trims read so much different than the WB error? Should the fuel trims be grouped tighter than they are if the WB error is within 1% lean? I mean, they range from -5.9 to 5. of course, not including the decel areas that see greater lean percentages. Maybe I need to use the STFT vs o2's method? I'm just shocked that the WB error can be so close but the trims are way off..

[JasonHSV]

Think of it this way, the WB is within 1% because the NB's are doing their job.

[LS ROB]

I'll start tuning with the NB's and see how that plays out. Thanks for your input, Sir!

[JasonHSV]

No problem. Use the STFT + LTFT math and remember to reset LTFT in the scanner after making changes.

[LS ROB]

will do.

[blindsquirrel]

Are you doing any filtering by Fuel Trim Cell?

[LS ROB]

Are you doing any filtering by Fuel Trim Cell?

No Sir. I don't understand how to build filters just yet. Honestly, i've gotten caught up in the tuning process and haven't spent much time on filtering. The only filtering I do is 25 hits per cell.

[blindsquirrel]

If you're not filtering out stuff that adds garbage to your data you're going to go around in circles. Putting it off isn't saving you any time, just the opposite.

[Alvin]

In your current tune you have the narrowbands in control of the fuel adjustment and your wideband is reading the results of that adjustment, so the data is as you would expect.

Everyone has their own thoughts on this, but I always use the factory narrow band sensors for closed loop fuel adjustments and save the wideband for WOT tuning. When you're finished tuning and go back to closed loop, the narrow band will take control anyway and they are extremely accurate at lambda 1.

I agree 100% only caveat is some larger cams.. The narrow bands simply won't get along with them. Usually in the 230 degree + on intake side you start running into this.

[Alvin]

Jason, why do the Fuel trims read so much different than the WB error? Should the fuel trims be grouped tighter than they are if the WB error is within 1% lean? I mean, they range from -5.9 to 5. of course, not including the decel areas that see greater lean percentages. Maybe I need to use the STFT vs o2's method? I'm just shocked that the WB error can be so close but the trims are way off..

A lot of people don't understand that there are purposefully switching lean to send oxygen in the cats. If the mix is stoich than the CAT will not be able to "burn" off any left over. So if you average out what a wideband reads over a well trimmed closed loop car the average will be slightly lean and this is correct.