Throttle response with fuel injection

[kircher]

Hi all.

For a while now I've been wondering about throttle response with fuel injection. In my experience cars/bikes with well tuned carburettors have had throttle response that absolutely shat on the fuel injected cars I have driven. Am I just driving the wrong fuel injected cars? Some of the fuel injected cars I've driven also had electric throttles which made it even worse. The fuel injected cars I've driven are as follows, from best to worst:

V6 Magna
1996 Subaru Liberty (daily driver)
2007 - 2008 Toyota Corolla (electric throttle)
2008 Toyota Yaris (electric throttle)
2005 Peugeot 307 (electric throttle)

And the carburetted vehicles (in no particular order):

4.9 XC fairmont (my Ford)
Datsun 180B
202 Kingswoods
1998 Harley Davidson

Now as I understand it when you put your foot down in a carbed vehicle, the accel pump squirts fuel into the airstream as the throttle plates move, providing response only limited by the distance of the carb to the intake valve and the speed of sound (the pressure wave as the throttle position changes), with other variables such as the cam also playing a role here. With a fuel injected engine, when the throttle position is changed, the computer has to respond and adjust the fuel squirt accordingly, thus creating a delay.

Of the vehicles I've driven/ridden, the Harley was by far the most responsive (it has a CV carb), and the other cars had basically equally good throttle response. Of the fuel injected cars I've driven, only the Magna has response that was close to the carbed ones, then followed by the Liberty. The worst was definitely the Peugeot. It was so bad that I stalled it on take off a lot because the throttle simply didn't respond quick enough to me pulling the clutch out. When making a high RPM gear shift, it would continue to rev even after I had taken my foot off the accelerator and put my foot on the clutch. The Yaris was the same, although not as sloppy on take off. The Corolla was an auto, but was still not responsive.

Now I can understand a Mercedes Benz with a 380kw 630Nm V8 having an electric throttle to make take-offs and accelerator adjustments smooth and not jerky to suit the personality of a high powered luxury car and it's need to waft along and not behave like a 1960s big block Muscle Car. Why should a gutless Yaris or 2 litre Peugeot be made even worse with a throttle with a half second delay to any change in position?

Now my main question is; can fuel injected vehicles be made to have excellent almost instantaneous throttle response? If so, I guess I've been driving bad fuel injected cars. Still, I don't see why anyone would want their car to do anything other than what their hand and feet dictate. Any other inputs to this topic are greatly appreciated. I want to know as much about this subject as possible

Sorry about the long post

Kircher

[phillyc]

Originally Posted by kircher

Now my main question is; can fuel injected vehicles be made to have excellent almost instantaneous throttle response? If so, I guess I've been driving bad fuel injected cars. Still, I don't see why anyone would want their car to do anything other than what their hand and feet dictate. Any other inputs to this topic are greatly appreciated. I want to know as much about this subject as possible.

Kircher

Much of what you have mentioned with trailing throttle response (tendency to keep revving or engine revs dropping slowly) is emissions related.

Having a quickly shut throttle would probably increase NOx emissions. Hence the electronically controlled throttle.

Electronic throttles also allow for better traction control.

PS Yes the Magna has one of the more responsive engines of cars i've driven too.

[XR Martin]

You havnt exactly driven a great selection of modern cars.

[kircher]

Originally Posted by XR6 Martin

You havnt exactly driven a great selection of modern cars.

Which is why I asked the question "am I driving the wrong cars?"
The two Toyotas and Peugeot are what I would call modern, and are small capacity so could benefit from better throttle response. So you are saying it is possible to have excellent throttle response with fuel injection? If so, then great. I still can't see how it is physically possible for an electric throttle to respond as quickly as one that is opened at the instant your foot moves. Enlighten me.

[XR Martin]

The time it takes for the fuel to leave the carb jet is probably longer than it takes a computer to tell the injector to fire. Electrons move pretty quick....Quicker than a vacuum.

VN Commodore is one fuel injected car that I can think of from the factory which had a stupid amount of throttle response.

Its more got to due with how its programmed to operate, rather than the design. Carbs on the other hand doesnt have that flexibility.
I imagine something like a F430 would have pretty instantaneous throttle response.

[kircher]

Originally Posted by XR6 Martin

The time it takes for the fuel to leave the carb jet is probably longer than it takes a computer to tell the injector to fire. Electrons move pretty quick....Quicker than a vacuum.

VN Commodore is one fuel injected car that I can think of from the factory which had a stupid amount of throttle response.

Its more got to due with how its programmed to operate, rather than the design. Carbs on the other hand doesnt have that flexibility.
I imagine something like a F430 would have pretty instantaneous throttle response.

When the throttle is opened in a carb, the tendency is for it to have a lean moment, due to the delay in the jets response, but you have an accelerator pump directly linked to the throttle to compensate for that. Also, those electrons have to respond to the throttle as well though. Usually a change in vacuum as well isn't it?

But this is good information. I would love to drive a 430 scuderia, but I can't afford one... yet.

[greenfoam]

I think you are driving the wrong cars man All my injected cars have been much more responsive than carby and yes you can easily give injected cars a big pump shot of juice if that's how you like it. These days they tend to tame them down a bit so you don't have too much grunt (Holden have been worried about this ever since the great plauge of looped around granny driven VN's in 1988 :p). My mum actually test drove a 1988 VN when I was a kid just when they were first released, she refused to buy it because it was "scary" compared to her VH she was ready to buy too, but nope, couldn't handle it

[kircher]

at risk of offending people on this forum, maybe I should get a VN...

[FPV+fteT3]

I have 3 cars at the moment all efi and the most expensive has the slowest throttle response it is the only one that has electronic throttle control, both the cable operated efi units respond quicker on both acceleration and deceleration. The FPV and the TE50 have both been tuned and use flash tuners and the tune used makes no difference to the throttle response time.
I think the electronic throttle and TPS set up could be improved.

The Subaru system is pretty quick response as does the TE possibly due to a cable actually opening the butterfly in the throttle body and not using several electronic sensors the ecu and electric motor to do what is a basic job that is open a butterfly.

You notice it less if you drive the one car but when you jump from one to another you have to change your driving style or timing to keep it smooth.
Just my opinion but I have to agree with the OP stab the loud pedal in my old XAGT and it barked straight away good old Holley all the new stuff is on delay.
damn young uns dont want to work......LOL.

[DougM]

I think what it comes down to is the throttle body and the fact that most efi cars have 1 throttle body with probably 500-600mm of pipework to it. When you hit the go pedal, it takes some time for the air to reach it and then pass through the TB. Look at BMW's for example and I know the older M3 sixes and the current V8 have individual TB's for each cylinder.......

When I was modifying my escort I had the option of the newer Sierra efi or go for webers. I went with the mechanic's advice and fitted twin 45mm webers. It is the most entertaining car to drive I have ever owned.......The throttle response was virtually instant......I loved it...........I've had an XR6T and now an XR8 which are way faster than the Escy but I just loved drining that car fast......

[kircher]

Originally Posted by DougM

I think what it comes down to is the throttle body and the fact that most efi cars have 1 throttle body with probably 500-600mm of pipework to it. When you hit the go pedal, it takes some time for the air to reach it and then pass through the TB. Look at BMW's for example and I know the older M3 sixes and the current V8 have individual TB's for each cylinder.......

When I was modifying my escort I had the option of the newer Sierra efi or go for webers. I went with the mechanic's advice and fitted twin 45mm webers. It is the most entertaining car to drive I have ever owned.......The throttle response was virtually instant......I loved it...........I've had an XR6T and now an XR8 which are way faster than the Escy but I just loved drining that car fast......

I've heard great things about DCOE webers on 4s and straight 6s. Triple webers on a 265 hemi would have to be an unreal experience. The sound would be awesome.

[jonk]

The VN throttle response was fly wheel related. I use to sell the VN brand new. Case of first ever mating of a front wheel driven engine design that drove rear wheels. Hoon laws back then would have got a lot of people in trouble.

[kircher]

Originally Posted by jonk

The VN throttle response was fly wheel related. I use to sell the VN brand new. Case of first ever mating of a front wheel driven engine design that drove rear wheels. Hoon laws back then would have got a lot of people in trouble.

Ok, so that's not really a case of throttle response from a better fuel injection set-up at all then.

I'm surprised there aren't more responses to this thread. I would especially like to hear from people who drive high performance fuel injected cars, since I've only driven gutless 4s, with really bad response. My old datto that I learned to drive in, although still a gutless 4 was a much more lively thing to drive than anything new I've driven. What are cars that are supposed to be lively like? eg Fiestas and the fuel injected windsors and the 5.4 Modulars that people drive?

[Kenaz]

Originally Posted by kircher

What are cars that are supposed to be lively like? eg Fiestas and the fuel injected windsors and the 5.4 Modulars that people drive?

Fuel injected Windsors are a nice motor, even the lowly 165 kW E series ones are quite responsive.

The 5.4s have pretty good response too.

[Bossxr8]

Electronic throttles always seem to react slow, they are most likely set that way from factory for reduced emmisions. Give me a cable anyday. I hate the lack of feel in the pedal of any post BA Falcon. You just don't have much of a clue as to how much throttle you've given it. With a cable throttle its a lot easier to feel how much throttle you have.

Flash tuners can speed up the electronic throttles I think.

[kircher]

After googling for a little while I discovered my experience is not unique. Other people on BMW, Mazda, Ford, Mercedes Benz and Dodge forums all have complaints with their drive-by-wire systems. Unfortunately the manufacturers have found a new way to further isolate drivers from the road. Drive by wire is here to stay. Maybe I'm part of a dying breed of people who value "feel" in a car. I always thought of throttle response as a good thing to have.

[XR6Runner]

Originally Posted by kircher

After googling for a little while I discovered my experience is not unique. Other people on BMW, Mazda, Ford, Mercedes Benz and Dodge forums all have complaints with their drive-by-wire systems. Unfortunately the manufacturers have found a new way to further isolate drivers from the road. Drive by wire is here to stay. Maybe I'm part of a dying breed of people who value "feel" in a car. I always thought of throttle response as a good thing to have.

Too true! I thought I was the only one that thought the new ETC was crap. I get absolutely no throttle response with the electronics taking place. The good old cable was the best. I'm now glad to know there are others who feel the same. I can compare it to driving a car in a video game. You press the accelerator, but feel nothing.

I have been tempted to modify my car to remove the ETC and replace it with a cable system. I just miss the feel of the throttle.

[XR Martin]

Flywheels in Autos dont really do much, so its not the reason for the VN's throttle response.

VN's response came down to the low first gear, low weight, its torque curve and its tune.

I know with AUs apparently they got Jackie Stewart to work on the drivability and he dictated that you should be able to have a coffee in your lap and be able to accelerate smoothly from a set of lights without spilling it. Could be BS but I did hear it at the Ford proving ground a few years ago.
You certainly couldnt do that with a VN. 99% of the population dont want neck snapping response off the line, not only dont the buyers want it, neither do the engineers as it puts more stress on driveline components.


Aurions are fairly responsive, probably the most of any vehicle with electronic throttle that ive driven.

[GS608]

Originally Posted by XR6 Martin

Flywheels in Autos dont really do much, so its not the reason for the VN's throttle response.

VN's response came down to the low first gear, low weight, its torque curve and its tune.

I know with AUs apparently they got Jackie Stewart to work on the drivability and he dictated that you should be able to have a coffee in your lap and be able to accelerate smoothly from a set of lights without spilling it. Could be BS but I did hear it at the Ford proving ground a few years ago.
You certainly couldnt do that with a VN. 99% of the population dont want neck snapping response off the line, not only dont the buyers want it, neither do the engineers as it puts more stress on driveline components.


Aurions are fairly responsive, probably the most of any vehicle with electronic throttle that ive driven.

Have to agree there, we had an Aurion AT-X as a renter. This thing flew!! hate to say it but it sounded pretty damn good at WOT as well. Compared to our FG XR6 it felt just as quick.

[Rev28K]

Originally Posted by XR6 Martin

99% of the population dont want neck snapping response off the line, not only dont the buyers want it, neither do the engineers as it puts more stress on driveline components.

I’d say that the reverse is true.

I’ve talked with an ex-production engineer from Ford. He said that Ford (and Holden and Mitsubishi) all strived to give the impression of a lot of torque at low accelerator openings through various means even if it means less response at higher accelerator openings. The idea is that the buyer thinks “gee this things got some stick what a grunty engine”.

My daily driver Honda develops max torque at 5500rpm, revs to 8800rpm and has a mechanical throttle. I can always work out what and when it is going to do even when VTEC kicks in around 5-6000rpm. When I jumped in to an FG XR6T the response to the accelerator travel seemed very disproportionate. It was a case of “wow that’s more torque than I really wanted” at low openings and “hey where did all of the shove go” at higher openings.

While I realise that a taxi motor with a turbo is never going to feel the same as my engine at high revs I really found the response of the Ford engine weird. Nismo have found the same thing and when they reflash their custom tunes they tune the cars for a more even & gradual response that directly corresponds with what the accelerator’s position.

[futura97]

take an ea - au for a drive. They have pretty good throttle response compared to other cars I've driven.

[atec77]

Originally Posted by kircher

Hi all.

For a while now I've been wondering about throttle response with fuel injection. In my experience cars/bikes with well tuned carburettors have had throttle response that absolutely shat on the fuel injected cars I have driven. Am I just driving the wrong fuel injected cars? Some of the fuel injected cars I've driven also had electric throttles which made it even worse. The fuel injected cars I've driven are as follows, from best to worst:

V6 Magna
1996 Subaru Liberty (daily driver)
2007 - 2008 Toyota Corolla (electric throttle)
2008 Toyota Yaris (electric throttle)
2005 Peugeot 307 (electric throttle)

And the carburetted vehicles (in no particular order):

4.9 XC fairmont (my Ford)
Datsun 180B
202 Kingswoods
1998 Harley Davidson

Now as I understand it when you put your foot down in a carbed vehicle, the accel pump squirts fuel into the airstream as the throttle plates move, providing response only limited by the distance of the carb to the intake valve and the speed of sound (the pressure wave as the throttle position changes), with other variables such as the cam also playing a role here. With a fuel injected engine, when the throttle position is changed, the computer has to respond and adjust the fuel squirt accordingly, thus creating a delay.

Of the vehicles I've driven/ridden, the Harley was by far the most responsive (it has a CV carb), and the other cars had basically equally good throttle response. Of the fuel injected cars I've driven, only the Magna has response that was close to the carbed ones, then followed by the Liberty. The worst was definitely the Peugeot. It was so bad that I stalled it on take off a lot because the throttle simply didn't respond quick enough to me pulling the clutch out. When making a high RPM gear shift, it would continue to rev even after I had taken my foot off the accelerator and put my foot on the clutch. The Yaris was the same, although not as sloppy on take off. The Corolla was an auto, but was still not responsive.

Now I can understand a Mercedes Benz with a 380kw 630Nm V8 having an electric throttle to make take-offs and accelerator adjustments smooth and not jerky to suit the personality of a high powered luxury car and it's need to waft along and not behave like a 1960s big block Muscle Car. Why should a gutless Yaris or 2 litre Peugeot be made even worse with a throttle with a half second delay to any change in position?

Now my main question is; can fuel injected vehicles be made to have excellent almost instantaneous throttle response? If so, I guess I've been driving bad fuel injected cars. Still, I don't see why anyone would want their car to do anything other than what their hand and feet dictate. Any other inputs to this topic are greatly appreciated. I want to know as much about this subject as possible

Sorry about the long post

Kircher

It's not the injection but the control , I have a chev powered Jag here injected and it's much more responsive now than when running the 750dp but it's hard wired from the peddle

[Mr Hardware]

I've never found Fuel Injection to be the blame for poor throttle response, but i've often found electronic throttle to be a huge problem and i hate it so much.

[castellan]

Well what i have found with EFI it is also the plumbing of the air entering the motor from the inlet to the air filter then to the throttle body. a snorkel directly in front of the throttle body with no restriction helps a lot. but that said a double pumper carby is the way to go for response. and DCOE webers don't respond like a double pumper.

[ea90gl]

This is also why I'd take a manual box over auto anytime of the day, response is heightened majorly. Whenever I drive an auto through the city where there is planty of variation of throttle the motor feels almost "disconnected" from your foot. If you sit in top gear at 60km/h with any manual, even though the car is completely out of it's prime, you will feel response instantly with any form of throttle application. However at the same time, Im sure most cars are different and the more power the car has the more responsive it will feel.

[Glow_Mouse]

well i dunno about you guys, but my Festiva's Response is straight to the point. Currently running a B5 16v Fi. Simple cable operated throttle body. The only real difference is the amount of Fuel/Air ratio that differs for the power.

Just my 2 cents. I've never had any problems with my car in the ways of response. It's a manual, takes off like a rocket. No turbo needed....yet.

[FalconXV]

You know I'd have to agree with you Glow Mouse, my mothers WF(?) Festiva has excellent throttle response, and seems alot perkier than a 1.5 oughta ( except now it sounds like a tappety trundle wheel on it's death bed), I hate to say it but awful steering and body aside, I genuinely enjoy driving it.

[Glow_Mouse]

Festiva's Cable throttle body is an exact of a honda civic 3dr hatch's. They have no dependent cpu, although there is still one in there somewhere. Gotta love the old tech.

Well most Festiva's have a smaller turning radius, hence no power steering, BUT having said that most of them are equipped with the PS drive pulley, just no belt. Many people look down on Festiva's as shoppin carts or go-carts. Well....yea, but if given a little love and some well thought out strategy, they can hoon like hell. I've had my festy for about 5yrs, replaced the gearbox and drivetrain, upgraded the intake, exhaust system, ignition system.

Runs like a bat out of hell. Even given the skylines somethin to chase.

[FalconXV]

Would you consider replacing it with a B20T or some kind of half cut? or would that take away the Throttle response?

[Mr Hardware]

wow glow mouse, sounds great, it's just a pity that any old cabbie would hose you in the traffic light grand prix