what the hell, it's not even a "pedal", its a potentiometer with a lever ****. put the pot to the metal, baby.

 

macncheese,

Again, correct

In trying to simplify an answer for understanding purposes, you sometimes lose the detail.

The throttle body opens and closes based on the ECU telling it that the "gas" pedal has been pressed. On the MINI, we have an "E-gas" or drive-by-wire, which means that the computer actually tells the throttle body when to open and close, not the pedal (which is conventional - usually through a cable or rod), activated through a DC motor with gearbox. When the driver presses the accelerator, the action is transmitted to the Engine Management System (a Siemens EMS 2000), which then determines the ideal amount of fuel to supply to the engine. With more powerful acceleration, the system can determine the best fuel feed for maximum performance and minimum emissions. The most important task for the EMS is: monitoring the engine torque, optimizing torque values and guaranteeing an even fuel take-up. If the required torque is below the maximum value available, it is possible for the EMS to retard the ignition timing and create a torque reserve.

When the throttle body opens, it is allowing the air into the circuit. The fuel is also regulated through the ECU, and enters at the fuel rail through the fuel regulator. The regulator maintains 3 bar of pressure. At the fuel injector, there is a fuel solenoid.

The electric fuel injection solenoid precisely meters the amount of fuel entering the combustion chamber. This is achieved via fluid flow calculations and precise timing.
For example, if you were to measure the amount of fluid g, in cubic centimetres (cc) that passes through the injector solenoid over a span of one minute, while the inlet fluid pressure into the solenoid was regulated at constant pressure d, then the flow rate of the injector solenoid, at fixed inlet pressure d, is known. The flow rate would then be the quantity of fluid g divided by the time the solenoid was open, one minute, thus FLrate = g in cc per minute.

The injector solenoid consists of a valve body and the needle valve with fitted solenoid armature. The valve body contains the solenoid winding and the guide for the needle valve. When there is no current flowing in the solenoid winding, the valve needle is pressed against its seat on the valve outlet by a helical spring. When current is passed through the solenoid winding, the needle valve is lifted from its seat and the fuel can stream through the annular orifice. The rise time of the injector valve is important when calculating the amount of fuel to be injected into the chamber. This is what is determined by the ECU.

So how is it all tied together - the air and fuel delivery, the spark, etc. We've mentioned the ECU (or EMS - the ECU on the MINI is the Siemens EMS 2000). This system controls fuel injection, ignition timing, closed loop fueling, an electric throttle body, knock sensing, engine cooling fans, and high-speed real-time serial communications using "computer area network" (CAN) protocol to manage traction control and CVT systems.

The closed loop EMS calculates variables detected via the various input sensors on the engine and then sets the completely separate timer module that runs the engine. Every new scan cycle of the program, new variables are calculated. If change has occurred from the previous cycle, the timer module will be updated. A sophisticated on board diagnostics (OBDII) system monitors the engine sensors and actuators to determine a fault, if one were to occur.

So why does the MINI (and most other new cars out there) utilize such a complicated system? With such a system, the injectors can be positioned to channel their spray directly into the intake valve, thus reducing the possibility of fuel touching the chamber walls. The major issues for using multi-point fuel injection over carburetors or throttle body port injection are lower exhaust emissions, better fuel efficiency, increased performance and individual fuel control into each cylinder (thus decreasing the effects of knocking).

I know it sounds complicated, but what it adds up to is a system that monitors itself, controls the variables through several sensors, and delivers fuel, air and spark based on the best available curves.


Hope that helps

Randy
randy@mini-motorsport.com

 

For example, if you were to measure the amount of fluid g, in cubic centimetres (cc) that passes through the injector solenoid over a span of one minute, while the inlet fluid pressure into the solenoid was regulated at constant pressure d, then the flow rate of the injector solenoid, at fixed inlet pressure d, is known. The flow rate would then be the quantity of fluid g divided by the time the solenoid was open, one minute, thus FLrate = g in cc per minute.

Good god.... My head hurts..

_________________
(03 MCS DS/DS) anthracite dash with panther black leather -- cold weather package -- sport package -- trip computer -- HK Stereo

 

What a great description. Were I anywhere near you, Randy, I would definately have you service (and tune) my Mini... many kudos for a great disertation (so I screwed up that spelling!).

 

One more thing, an earlier post asked if pulling the throttle body and enlarging it's opening and fitting a new butterfly valve wouldn't accomplish the same thing for less money? Are there electronic differences?

 

>>So why does the MINI (and most other new cars out there) utilize such a complicated system? With such a system, the injectors can be positioned to channel their spray directly into the intake valve, thus reducing the possibility of fuel touching the chamber walls.


Randy,
I think we're generally on the same page about things but you've lost me here. I think you mean there is less chance of the fuel sticking to the plenum/manifold walls, not the chamber walls but Im not sure? Since you seem to be digging a lot deeper into this engine that I am, whats the flowrate on these injectors? Thanks.

--
Cheese

 

Did I read correct?

Step nine tells you to reconnect the fuel line? Is there fuel running through the throtle body? If so why?

 

Fuel vent line.

 

Hey Randy!
Thanks for the info! Would this help with the pick-up or would a lighter flywheel be a better option if rev pick-up is your goal.

 

The flywheel would definitely help there, but the labor is extreme! The motor and gearbox, as well as the front suspension on the driver side, just about have to come off the car.

macncheese,

The pressure regulator provides a constant pressure of 3 bar to the injectors.

As far as the combustion chamber issue - if the mixture can be directed into the chamber without touching the chamber walls, a more complete combustion can be had without any "hot spots" along the cylinder.

Hope that helps!

Randy

 

>>The flywheel would definitely help there, but the labor is extreme! The motor and gearbox, as well as the front suspension on the driver side, just about have to come off the car.
>>
>>macncheese,
>>
>>The pressure regulator provides a constant pressure of 3 bar to the injectors.
>>

Is that 3 bar of absolute pressure upstream of the injectors, or 3 bar across the injectors, like the systems with vacuum-referenced FPR's?

>>As far as the combustion chamber issue - if the mixture can be directed into the chamber without touching the chamber walls, a more complete combustion can be had without any "hot spots" along the cylinder.
>>
>>Hope that helps!
>>
>>Randy

As far as fuel on the walls of the COMBUSTION chamber (that is what you mean, right?) why would it matter if the fuel is injected immediately before the intake valve or quite a bit upstream? As macncheese stated, multi-port injection reduces the fuel condensation in the intake manifold runners, not in the combustion chamber. Any "hot spots" inside the cylinder have to do with airflow patterns and combustion chamber design.

 

how much in-town driveability is lost with this tb? my car (zx3 focus) came stock with a 52mm tb and i switched over to a 65mm unit, obviously the difference was a bit extreme. took about a week to really master the thing, but it was well worth it.

is the stock standard cooper tb the same size as the stock s tb?

are the aftermarket units the same size?

Nate

 

>>The flywheel would definitely help there, but the labor is extreme! The motor and gearbox, as well as the front suspension on the driver side, just about have to come off the car.
>>
>>macncheese,
>>
>>The pressure regulator provides a constant pressure of 3 bar to the injectors.
>>
>>As far as the combustion chamber issue - if the mixture can be directed into the chamber without touching the chamber walls, a more complete combustion can be had without any "hot spots" along the cylinder.
>>
>>Hope that helps!
>>
>>Randy

Randy,
No fuel injector location short of direct injection is going to steer away fuel from clinging to you cylinder walls.

--
Cheese

 

>>my car (zx3 focus) came stock with a 52mm tb and i switched over to a 65mm unit, obviously the difference was a bit extreme. took about a week to really master the thing, but it was well worth it.

Can you describe the difference in you ZX3?

 

>>>>my car (zx3 focus) came stock with a 52mm tb and i switched over to a 65mm unit, obviously the difference was a bit extreme. took about a week to really master the thing, but it was well worth it.
>>
>>Can you describe the difference in you ZX3?

well, to put it simply i fried a bit of the clutch the first time i tried backing up after putting it on. the combination of increased airflow + lighter throttle spring (i don't have a fancy electronic throttle like you guys) made the car very touchy. i got used to it, but the car whistles loudly at partial throttle thanks to the large volume of high velocity air whizzing past at half open butterfly.

stock tb:

Focus Central 65mm throttle body:

as you can see it's quite a bit of difference in size. hence the big difference in response/airflow. i'd love to see what kind of difference a larger unit makes on your cars.

Nate

 

Another great article and pics.

One question. There have been postings here and elsewhere that the OEM throttlebody does not open 100%
Does this new TB correct that issue? At WOT I'd like to have a 100% open butterfly. If it still only does the reported 85% of the OEM TB I'd be disappointed. Unless there is some reason that makes it unecessary to open all the way.

Thanks

 

Awesome write up Randy, but this whole things kinda peeves me. I just had my list made-up and my budget worked out for the mods to the new MINI and you had to throw this into the mix -

For the money and for the first set of engine mods would you suggest the Madness-Intake and Nology Wires or the Madness Intake and the Throttle Body?

I just need more $$$$

 

I think the reports of the throttle not opening fully has to do with the resolution of the sensor measuring throttle position. It gets kinda wacky as you approach the limits of the sensor, sort of like wideband versus narrowband O2 readings. My highest reading is 92%. I'll log it and post a graph later if anyone is interested but I'm sure Andy @ Rosstech has one handy :smile:


--
Cheese

 

I take it that means this new TB comes without it's own TPS? Bummer.
The again 92% is better than I remembered. No surprise there.

 

The throttle body uses a pair of potentiometers to measure the angle of the throttle plate. The potentiometers are oriented opposite one another, so as the reading from one goes up, the other goes down. This is a redundancy feature in case one potentiometer fails. There is a similar pair of pots in the accelerator pedal. Anyhoo, the deal with potentiometers is you shouldn't use the very lowest or highest areas of their range. Potentiometers become inaccurate at their extrema. So, the range from closed throttle to WOT may go from 12% to 88% or something like that. I would never expect to see 0% or 100%.

 

Excellent explanation Andy.

 

Great write up. So any comments to post on the end performance gains of this modification?

Thanks,
Jim

 

check out this throtle body combo, (go to the end of the article and hit the bodymotion link; its linked again in the middle of the page
http://www.nuzzomotorsports.com/

 

Yeah, that is the Bosch unit they are using in conjunction with the Motec. It is slightly smaller (1mm) than the stock unit, and requires a throttle cable and stand alone engine management. Very trick looking though!

Randy

 

Has the throttle body interest taken a back seat to the pulley install.They seem close in price after labor costs.However I feel more comfortable with the do it yourself throttle body.Is there any dyno proof of the throttle body hp gains.