[113943]

I am trying to understand how my Pro Ceed uses no fuel on rundown as described recently on the forum. I searched the internet looking for modern cars idling designs. I found information explaining that four different methods are commonly used. The one that caught my attention was the one using a Pintle valve. It described it as a variable valve coupled with a piece of electronics that reads a list of “If’s” and opens the valve to different setting accordingly. This”IF” list sounds fascinating and wondered if a member could go through it for me please? I can see the possible start up instructions as been something like “ On cold start up open valve to setting four and reduce to setting one when engine temperature is at XXX”. Or, If heating fan is switched on increase idling speed to setting two.
I am particularly interested in the “shut valve” instruction to save fuel during rundown, in gear, and with throttle closed?
If My Kia does not use the pintle type idling control would any expert bear with me and still explain this system please.

 

[skidlid]

Here is a link to a site.

Overrun Fuel Cut — Link Engine Management Systems - plug-in & wire-in aftermarket ECU's

Why 2 identical posts, is that necessary?

 

[Ace Demon]

I am still trying to understand how my Pro Ceed can be using no fuel at all on rundown

You're overcomplicating things but you need to start with a distinction between idling and overrun.

Overrun is simple for either petrol or diesel, where all that has to happen is that no fuel is injected.

The ECU knows what speed the engine is doing by interpreting the timing between pulses from the crank sensor. Too fast, less fuel, too slow more fuel.
Modern fuel injectors offer such fine control that no extra gubbins is needed other than that for a petrol engine there is an air bypass round the throttle that the ECU also needs to tweak.

The injectors are indeed quite remarkable things. If my maths is working, at idle they are delivering something like 60 microlitres during each firing stroke (0.3 gallons per hour). On a 150bhp engine running flat out (say, 5.8 gallons per hour) it rises to about 220 microlitres per stroke. A diesel injector has to be able to deliver this in probably less than half a millisecond. The actual amount delivered will be proportional to the length of electrical pulse issued by the ECU.

That's just a mechanical problem. Creating the electrical pulse for the injector with a resolution of a fractions of a millionth of second is very easy. For instance, for you to be able to read text on your computer monitor, it has to be able to complete the process of going from white-black-white in 12 billionths of a second.

 

[113943]

Here is a link to a site.

Overrun Fuel Cut — Link Engine Management Systems - plug-in & wire-in aftermarket ECU's

Why 2 identical posts, is that necessary?

Why two posts, I entered my posting then went on to read the forum. Noted my posting had not been entered and assumed I had made a cock of posting it. :-ie Posting was a little slow to enter today. Can't think of any way to make this clearer to understand. Sorry.
Have used computers long before Windows was devloped and still making mistakes. Sad is'nt it? Just wait until you you hit eighty one!

 

[113943]

You're overcomplicating things but you need to start with a distinction between idling and overrun.

Overrun is simple for either petrol or diesel, where all that has to happen is that no fuel is injected.

The ECU knows what speed the engine is doing by interpreting the timing between pulses from the crank sensor. Too fast, less fuel, too slow more fuel.
Modern fuel injectors offer such fine control that no extra gubbins is needed other than that for a petrol engine there is an air bypass round the throttle that the ECU also needs to tweak.

The injectors are indeed quite remarkable things. If my maths is working, at idle they are delivering something like 60 microlitres during each firing stroke (0.3 gallons per hour). On a 150bhp engine running flat out (say, 5.8 gallons per hour) it rises to about 220 microlitres per stroke. A diesel injector has to be able to deliver this in probably less than half a millisecond. The actual amount delivered will be proportional to the length of electrical pulse issued by the ECU.

That's just a mechanical problem. Creating the electrical pulse for the injector with a resolution of a fractions of a millionth of second is very easy. For instance, for you to be able to read text on your computer monitor, it has to be able to complete the process of going from white-black-white in 12 billionths of a second.

Hello ace demon.
I had a small bet on with myself you would be the one to clear my query up for me. I always hate having to go on the net when something gets me thinking and I am getting nowhere. It seems the net has led me up a gum tree once again. Reading about the four commonly used idling idling sensors was so convincing and,when I got to the bit about the pintle valve, it seemed so clear. Thanks AD.
Johnfranklyn.

 

[113943]

Hello ace demon.
I had a small bet on with myself you would be the one to clear my query up for me. I always hate having to go on the net when something gets me thinking and I am getting nowhere. It seems the net has led me up a gum tree once again. Reading about the four commonly used idling idling sensors was so convincing and,when I got to the bit about the pintle valve, it seemed so clear. Thanks AD.
Johnfranklyn.

Hello ace demon. If you could have a look at www.autoshop101.com/h26,pdf I think you will see where I was led astray in my thinking. I failed to see it was a Toyota system and finding the pintle valve illustration seemed to answer my basic Production Engineers background experience. I should have taken more notice
johnfranklyn

 

[kiaceed]

Its really very simple. With a closed throttle and engine revs above the figure set by the manufacturer (normally about 1000-1200rpm) no fuel is injected. It is all controlled by numbers on a 3D map in the ECU. This condition is met constantly while driving eg lifting off when approaching a junction and although its not a major fuel saving at £1.40 a litre every little helps.

You do not notice it working on todays electronically managed cars but back in the early 80's I had a petrol car fitted with mechanical fuel injection that had possibly one of the earliest incarnations of a system like this. It was horrendous, the lifting off on an icy road was simply dangerous and when the fuel flow started again it was not smooth transition.

 

[113943]

Its really very simple. With a closed throttle and engine revs above the figure set by the manufacturer (normally about 1000-1200rpm) no fuel is injected. It is all controlled by numbers on a 3D map in the ECU. This condition is met constantly while driving eg lifting off when approaching a junction and although its not a major fuel saving at £1.40 a litre every little helps.

You do not notice it working on todays electronically managed cars but back in the early 80's I had a petrol car fitted with mechanical fuel injection that had possibly one of the earliest incarnations of a system like this. It was horrendous, the lifting off on an icy road was simply dangerous and when the fuel flow started again it was not smooth transition.

Thanks for the rundown kiaceed I have a good idea how it all works now. You get petrol at £1.40, you are a lucky man, its ten pence more up here in the Highlands

 

[kiaceed]

You get petrol at £1.40, you are a lucky man, its ten pence more up here in the Highlands

We get diesel at £1.40, £1.397 actually, petrol is £1.357.

 

[113943]

I am not green with envy. Much!