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missing acceleration enrichment tuning module

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I am from Belgium Europe.

Running a vipec i88 on a skyline r32, self learning, and getting info from a top tuner with 15years experience.

But now I have something I can't adjust.

With acceleration enrichment, when I kick throttle down, only under 2500Rpm it's lean to 17afr, from2500 a 2750 Rpm it goes to AFR 12.

Like I whan't to all the way to rev limit lowering to 11,5afr.

Below I don't get it richer when accelerating, so in that area of Rpm it hesitates, lack of power and that area is also used when leaving with car in first gear. Once past 2500Rpm starts pulling with love.

Tried accel clamp increase, etc...

Can you help me out, or make a module in the g4 tutorial or a webinar of it?

Cheers from sunny belgium

The first place to start with any accel enrichment tuning is actually to make sure your main fuel table is correctly tuned, particularly in any areas you're having trouble with. If the main fuel table isn't right you can end up trying to tune around this using the accel enrichment to compensate and then everything gets messy.

If you're main fuel table is correct and the AFR is on target as you drive through each zone then you can look at the accel settings. I find that the base settings in the Link/Vipec maps are usually pretty close to the mark and if you're having a lot of trouble often something else is to blame. In general the two settings you will need to adjust are the 'Accel Sensitivity' and the 'Accel Clamp'. If you need more accel enrichment it may be that you need to increase either the sensitivity, the clamp at the specific rpm, or both.

Another tip here if you are having trouble is to log the accel enrichment parameters and see what the ECU is actually doing. This can highlight a problem very quickly. For example there have been a number of times where I've had a noisy TPS sensor, or a delay in the MAP signal that has resulted in poor accel performance.

my main fuel table is in MGP and use modelled fuel.

the turbo pressure is coming fast and hard on.

is it an option i use 4d table , axis on TP and Rpm, and use this also ?

here's a scrfeenshot, i don't get the acceleration enrichment any righer????

do i need to raise the accel sensitivity even more higher as it is now allready on 40.

already enabled 4D fuel table, but still on 0

I've had a look over your map and your data log. I've attached a screen shot of the log and there are a few points I'll bring up that may help you:

1. Looking at your log around the 0:37 mark, the throttle is relatively consistent. You're sitting at about 1950 rpm, 95-100 kPa and 22-25% tps. The lambda however is very lean - 1.18. This suggests your basic fuel tuning is not correct. Go back and tune all of the fuel cells to achieve your target lambda before addressing the accel enrichment.

2. At the cursor point you can see the lambda dips very rich to 0.83. You can see this is a direct result of the fast change in tps and the requested accel enrichment pulse. This suggests that the accel settings are a little too aggressive.

3. Is there any reason you're using the modelled dual fuel mode as opposed to just 'modelled'? Dual fuel should only be used if you are genuinely expecting to run on different fuels - Pump gas and E85 for instance.

4. Your target lambda table is requesting 1.05 lambda at 0 kPa and then 1.00 at 20 and 40 kPa of boost at low rpm. I would suggest targeting 0.95 lambda at 100 kPa and then gradually target richer in positive boost even at these low boost levels.

I think you may find that you will benefit from the information in our EFI Fundamentals course as well as perhaps our Dyno Tuning practical course if you intend to do some tuning on the dyno. This will help you get the best results possible.

Let me know if I can help further.

yes i am going to run on E85 (flex fuel)

My Lambda target table was crappy, so made a new one, as you adressed , i forgot about the target table for guidance line when setting static fuel. I go on dyno this afternoon with this Lambda target table for static fuel table tuning and ignition table. then i hope the acceleration will be better.

Acceleration agfressive, you mean the "accel sens" or the "wake up" ?

As i noticed the wake up is and makes it more agressive and lowered it already, maybe need some more.

i think this is a better Lambda target map ?

I would copy your 1000 rpm target line across to the 1500 rpm line as this is still targeting lambda 1.00 under boost.

Both the accel sensitivity and clamp table can cause the accel enrichment to be a little too much. I can't tell you from the data which is your issue.

Good luck on the dyno.

As Simon said : Tuning the accel enrichment, is VERY important to have the fuel table as it need to be.

The dyno session went very good on setting fuel table, charge temp approx and everything else .

Now making very nice curves on lambda when pulling full load on the street. maybe just here and there a little adjustment, but they are very very small now.

when i have a new log, will make a nice screenshot with the result now.

on my experience, you cannot get the acceleration good with just a street mapping. You will need to go on dyno, for certain things you can't set on the street.

I am also having a similar problem on gear changes, A small lean spike as the TPS is increased again. Is this a delayed MAP reading?! Or can this be tuned out?!


it is delayed MAP response, but yes, I had it to, and you can tune it out.

As Simon said : first fuel main table must be correct. then go to accel enrichment.

even after going on dyno for main fuel table, I still needed to make small adjustments in fuel table to add some 1% 2% more in low Rpm zone 2000rpm to 3000Rpm from 0 MGP (100MAP Kpa).

and my lean spot was gone and engine response much better when leaving with car.

as you have lean spots to, you should also see lean spot when in 1th gear and start moving the car.

Hey @Gojira, it's actually Andre... Simon is my surname :) Believe me you're far from the first to get it wrong and I'm sure you won't be the last so I won't be too offended.

@Dan, it's not uncommon to see a small delay in the lambda trace on a gearshift, particularly if the engine entered overrun fuel cut off. It looks from your log like the engine possibly would benefit from a little additional accel enrichment however I tend to tune the accel partly by feel and partly from the wideband data. What I mean by this is that if there is a small lean spike like this but the engine response is clean and crisp then I wouldn't be too worried about what the AFR is telling me.

Thanks Andre, Actually feels like the car is hesitating a little as I come back on the gass after a gear change, It could be lag, but I have a feeling its fuel! Will add a little more to the clamp table and see what happens!


like Andre says, If I only did it on Lambda, I would give to much,

I feel my engine best response when leaving from 0 in first gear, it gets a little lean, about 1.05 Lambda for a very short time,

if I give it more it will BOG, first I did the adjustment in the Accel enrichment clamp table, but then I didn't get the response,

but the enrichment came some later on when it wasn't needed. (map delay or so)

So what I did was logging it, and in logging, point in log on graph where's it's a lean spot, and adjust with 0.1 0.2 in main fuel table where the log trace points.

and see tru logging how the engine response to it, and adjust even more when needed

now I did that, car pulls like a train.

can't you post a logging file and PCL from your link ? log some while driving and pull ups, save it and post here.

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