Recommended starting VE for bolt ons?

[TypeIsCheap]

The SD tuning guide mentions multiplying the stock VE table by 1.15 before starting to tune the VE tables (to protect against a too lean condition). I assume this is so you can tune from the rich to lean direction instead of vice versa.

Forum wisdom indicates that the VE tables need only minor tweaking for bolt ons (intake, headers, exhaust in this case) if at all and several of the "headers only" tunes I've reviewed from the repo confirm this.

I'll be tuning with a wideband and applying the AFR Error % to the VE table, does it make sense to start with a more reasonable VE bump, 5%-10% instead of 15%? Or log with the stock table first?

I'm only a "book learned" tuner at this point, looking for some real world experience here. Thanks!

[mowton]

Start with the stock VE (GM knew what they were doing...) and multiply by 10%. Then do a quick log across each of the MAP axis rows at any rpm axis point. Understanding that the delta error is about the same across a specific MAP regardless of rpm, all rpm values in that map row can be adjusted with the same percentage delta that you logged. That should get you very close. You will be running the VE only up to 4000 rpm, so you want it pretty good up to that rpm and only for transient states or MAF Sensor failure mode. MAF is the key for a stock bolt on.....

Ed M

[MikeOD]

Just keep your eye on the wideband when you do put the throttle down...if it goes lean...lift, add to the VE table and try again. If you go lean for a brief moment on a stock engine with headers, you're not going to hurt anything...if you hold it lean for a while, you will hurt it.

[TypeIsCheap]

Thanks for the feedback! Planning on using steady state to tune the VE up to 4000rpm and then tune the MAF for WOT. I'm going to take the WOT tuning easy and work my way up the rev band keeping an eye on the wideband display.

PE will remain enabled and I'll filter out any unplanned excursions into PE while in SD mode if needed.

[mowton]

PE will remain enabled and I'll filter out any unplanned excursions into PE while in SD mode if needed.

I see this a lot in threads where tuners want to filter out the data they get when in PE. The results of logging with or without PE are derived from the same place.....the difference between your commanded Lambda (AFR) and actual Lambda (AFR) so whether you are commanding 1.0 (14.2) or .87 (12.5) your fueling error % is the same and you can use it to update the MAF/VE at that particular spot. The key continues to be steady state data so as you enter and progress through PE, try and keep from experiencing throttle transient...similar to non-PE tuning. Don't waste good data :-)

PS -- I am strictly a Lambda tuner so that is why I lead with my Lambda ...........

Happy tuning

Ed M

[TypeIsCheap]

Yeah I read a few threads about this concept (AFR error is valid PE or not) and it makes total sense.

[mowton]

Yeah I read a few threads about this concept (AFR error is valid PE or not) and it makes total sense.

Transients are the unwanted scenarios which will make your data inaccurate...that is what you want to prevent against erroneous data 1) no hurky jerky motions on the pedal and use "visual" filtering of data to interpolate through transient frames.

Ed M

[RonSSnova]

I like that. Visual filtering!
Perfect!

Ron

[mowton]

I like that. Visual filtering!
Perfect!

Ron

Yeah, I don't know how else to explain it :-)

Ed M