Part throttle faster than full throttle

[Calum]

I'm gonna take a stab at the cause.

While you're at part throttle the ECU is running in closed loop mode, meaning that the sensors that provide feedback to the ECU so it can adjust trims such as air fuel ratio, cam phasing and ignition timing, are active and the ECU is using them to adjust those trims.

When you go to full throttle the ECU goes to open loop mode, no longer accepting those sensor readings, and using factory tuned maps to determine the engine parameters.

Clearly your ECU has found that's it's safe to run more aggressive trims then the factory WOT maps.

If I were you, I'd thanks the gas gods for having decent fuel, and contact a tuner.

[mad_sb]

Originally Posted by Calum

I'm gonna take a stab at the cause.

While you're at part throttle the ECU is running in closed loop mode, meaning that the sensors that provide feedback to the ECU so it can adjust trims such as air fuel ratio, cam phasing and ignition timing, are active and the ECU is using them to adjust those trims.

When you go to full throttle the ECU goes to open loop mode, no longer accepting those sensor readings, and using factory tuned maps to determine the engine parameters.

Clearly your ECU has found that's it's safe to run more aggressive trims then the factory WOT maps.

If I were you, I'd thanks the gas gods for having decent fuel, and contact a tuner.

The only feedback during closed loop is for AFR target, which is 14.7ish for closed loop mode. all the other maps, ignition, cams phasing etc act the same regardless.

[Calum]

Originally Posted by mad_sb

The only feedback during closed loop is for AFR target, which is 14.7ish for closed loop mode. all the other maps, ignition, cams phasing etc act the same regardless.

So, does that mean my explanation and thus understanding of this is plausible? Other then the AFR?

[ft_sjo]

It's to do with gas velocity.

[zooki]

Originally Posted by 350matt

In theory you may get a gain lower in the rev range with a slightly closed throttle as this keeps the gas speed up but as you approach higher rpm the throttle will then need opening up

is this the case?

I would think that with a partially closed throttle body the MAF would see less air flow and adjust the fuel accordingly. Less air, less fuel, less power.

[Anthony]

Lots of good theories so far. I have nothing to add, but I do hope this is the case:

Originally Posted by mid_life_crisis

Exactly. You only notice it when you stomp on the gas and expect to go somewhere.
This is definitely a driver's car. That doesn't just mean it's fun for a good driver. It also means you have to drive it well to get anything out of it, but it will reward you if you do. When you find yourself in a situation where you anticipate a likely need for sudden acceleration, downshift so you are above the torque dip and ready to go. When you stand on it, the car will take off nicely. Takes a little getting used to cruising along at 50 or 60 with the engine buzzing at 5,000 rpm but it works and it isn't usually for very long.

[wholeeoh]

i noticed the same thing lmfao thought i was the only one.

[Anthony]

@wholeeoh, your username instantly reminded me of Ling and Ling's Father from Kung Pow.

[atledreier]

Definetly noticed it too. I'm subscribing to the open/closed loop theory. Notice it both stock and tuned (N/A)

[Anaxilus]

Originally Posted by Grip Ronin

thats most small engines.. goin full throttle at a low rpm is jus flooding the engine with air that it cant use yet, which is also compensated with more fuel

Not really IME. It's more a phenomenon of more modern/economical engines seems to me. I've often thought it was part of an EPA and CAFE conspiracy for some automakers to keep their numbers up. I've driven plenty of older small displacement engines that respond at will during WOT. Depends on the design and tune of the engine I'd say. I don't see why bigger engines w/ more mass and frictional losses wouldn't be worse by that logic.

And yes, I noticed the part throttle effect during the gentle part of my break-in cycle. Was wondering if it was only in my head, guess not.

[ft_sjo]

Originally Posted by atledreier

Definetly noticed it too. I'm subscribing to the open/closed loop theory. Notice it both stock and tuned (N/A)

Because engines are happier running at stoich than richer mixtures, right?!

[Wise]

Stupid question.

But what is 'bogging'?

[mid_life_crisis]

Not sure the origin but I always interpreted it as meaning you expect to take off in a sprint but move like you are running in a bog.

[Hanni_0176]

Originally Posted by Wise

Stupid question.

But what is 'bogging'?

It's essentially lag, or a delay.

When you push your foot all the way down on the throttle, you expect an instant response from the engine to go faster. This is usually coined as throttle response.

Bogging is when you don't get instant response from the engine. There is a delay of time before the car starts to accelerate fast. Bogging can be as quick as a split second, or as long as several seconds or more.