When I tune a car that bucks...

[02Z0h6]

Hi Chad,

I would try to enriching the zone where the problem exist to the ~13.4/13.7 AFR value...

Try it when you have a chance and report back.

Christian

I'll give it shot Christian. How do I keep it from pulling fuel to maintain stoich?

[miami993c297]

I'll give it shot Christian. How do I keep it from pulling fuel to maintain stoich?

Running OLSD seems to be the best shortcut...

The easiest way would be starting to use the VCM Controls (I like play with it) and modify your AFR Control value under Fuel & Spark, pretty easy and straightforward...

I use it as an experiment tool that can be change in a second not stopping driving to understand and learn what the engine is comfortable with.

Regarding my conclusions I know if AFR is acting on my problem (low load bucking) and the engine reacting to fuel addition or fuel substraction in this zone in going from reach to lean...

That way of working was already described by Russ earlier...and if you cannot find a way to have your engine not having a nice combustion adjusting timing vs. fuel it is time to consider the Ignition System by itself or the Intake Peripheral System, I don't see the point of huge overlap with your camshaft design.

Waiting for your results
Christian

[02Z0h6]

Running OLSD seems to be the best shortcut...

The easiest way would be starting to use the VCM Controls (I like play with it) and modify your AFR Control value under Fuel & Spark, pretty easy and straightforward...

I use it as an experiment tool that can be change in a second not stopping driving to understand and learn what the engine is comfortable with.

Regarding my conclusions I know if AFR is acting on my problem (low load bucking) and the engine reacting to fuel addition or fuel substraction in this zone in going from reach to lean...

That way of working was already described by Russ earlier...and if you cannot find a way to have your engine not having a nice combustion adjusting timing vs. fuel it is time to consider the Ignition System by itself or the Intake Peripheral System, I don't see the point of huge overlap with your camshaft design.

Waiting for your results
Christian

Thanks Christian. I'll try and play with it and see what happens. As you pointed out, my cam doesn't have much overlap (1*) and that's why I feel driveability can be better. If I had a 24X/24X on a 110 then maybe I could live with it. By today's standards my cam isn't very big.

[mathef]

The low rpm boundary has to be ~100 rpm higher than your idle speed, then raise the high rpm to 2400, then have the mid rpm half way between. The low map boundary should be ~5 kpa higher than your idle map (in gear for an A4), then the high map should be 80-85 kpa, and the mid map half way between. These settings will enable all the fuel trim cells. This is because your idle rpm & map is higher than stock, so the low rpm & map fuel trim cells will be out of bounds and not used.

Yeah, the new cam, ported LPE heads, speed pro pistons & file fit rings really woke the car up!

Russ Kemp

Russ,

Above where you talk aboutThe low map boundary should be ~5 kpa higher than your idle map (in gear for an A4), then the high map should be 80-85 kpa, and the mid map half way between.Where is the idle map that you are talking about? I am having a similar issue and wanna give your method a shot.

thanks
frank

[Russ K]

These are the settings for my car.

Russ Kemp

[vandenberg33]

The solution for me was dialing in the fuel. Use vcm controls to turn spark idle off. I have ltft off as well since I have a large cam with 283 duration and 624 lift with lobe separation of 112. Log data after the car is warm. Fuel trims reset and fuel trim learn off. Log stft. Run the rpms through all the load cells while at idle that are affected by surge and make sure to maintain each load for enough time that the stft log stabilizes. After logging take the stft table and multiply by percent in the VE table. Soon your stft will be smoothed and you can fine tune while driving.