×

Sale ends todayGet 30% off any course (excluding packages)

Ends in --- --- ---

# Target vs Actual AFR Ramp Up

### Tech Articles

Discuss all things tuning in this section. News, products, problems and results.

Hi all, I've got a quick question regarding AFR, specifically the time it takes for my actual AFR to ramp up and approach the target AFR.

If you look at the attached log, you’ll see my actual AFR (in pink) and the target AFR (in purple), I was wondering if that initial gap between the actual and target AFR is normal? I've always wondered if this was fairly normal or if there's room for improvement here.

For what it's worth, I'm running a ProEFI computer on a single turbo Nissan 350Z.

Thanks! :)

I'm not sure what they call it in proefi but it looks like your acceleration enrichment is needing tightened up. There was a webinar on this not to long ago, it's using a Haltech but the principles are the same

Ah, thank you! Think I've located the screens where I'll need to make adjustments...

That's the one. There is a couple accel enrichment webinars so probably worth watching them all if you've never tuned this area before

Just wanted to share what I’ve found so far, in case we have any ProEFI cars on here.

After watching the ‘Tuning Acceleration Enrichment - Haltech Platinum PRO’ webinar and digging through the ProEFI software, I wound the ProEFI equivalents for acceleration enrichment.

ProEFI’s acceleration enrichment is dependent on three fields:

1. Accel Multiplier Upper Limit: Sets the maximum multiplier to the base fueling for accel fuel. For example, a value of 3 would allow 3 times the current fuel requirements (based on the VE table?)

2. Decel Lower Limit: Sets the minimum multiplier for decal fueling. For example, a value of 0.70 would allow 70% of the current fuel requirements

3. Delta TPS Filter Constant: Sets the length of time accel fuel decays once it becomes active; the greater the value the longer effect of the accel fuel. 0.05 is considered a typical value, when the number is increased to 0.09, accel fuel decays slower and stays in effect longer. When reduced to 0.03, accel fuel stays in effect for less time and decays quicker. (I believe this field is what needs to be adjusted for my tip in lean issue)

Once the rain stops, I’ll start making more adjustments to my Accel/Decel Fueling setup, it seems like increasing the ‘Delta TPS Filter Constant’ will fix the bulk of my lean tip in issue. I just need to find the smallest value I can use as increasing it from the current value of 0.04 to 0.09 seemed to work but the accel fuel lingered on for longer than what was necessary and destabilized AFR a tad.

Rather than adjusting the delta try adjusting the accel multiplier,that way the period of time that it is adding extra fuel isn't affected but you have added a larger volume.

As Andre mentions in the webinar that I linked it should be the minimum amount of enrichment to give crisp response and is not always about chasing a consistent AFR during tip in events

Since you're dealing with a turbo car, when you go to full throttle the manifold pressure is rising to your target boost pressure too. If this area of the fuel table isn't quite right then it can result in a discrepancy between your target and actual AFR too.

So is that where a map dot accel could come in handy?

We usually reply within 12hrs (often sooner)

#### Need Help?

Need help choosing a course?

Experiencing website difficulties?