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Old 11th May 2011, 07:12   #31
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Default Re: ECM changed, now what?

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Originally Posted by bblost View Post
Vehicles on top of a moving track. Like the exercise machines.
Now you can drive the vehicles using a machine, instead of a driver.
You mean a Dyno??


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Originally Posted by bzr77k View Post
1. As already mentioned by somebody, all mass-produced parts are subject to certain tolerances in their characteristics. If these characteristics, can be controlled by design, to not affect the performance, then there is no individual pairing required. But, if these tolerances, cannot be reduced due to cost/process/technology reasons AND if these tolerances can affect the system, then the ECUs are calibrated and the algorithms use a correction factor to account for these tolerances.
Each part (in this case, the injector for example... also some sensors) have tolerances which cannot be limited to the required amount and a correction factor needs to be introduced. This correction factor can be 'learned' into the system in two ways: i) by way of closed loop monitoring by the ECU itself (e.g. drive cycle), ii) by way of measuring the correction factor and programming it into the ECU (for e.g.: by reading the injector code)
The specific parameters that need to be compensated depends a lot on the system design and component selection (usually driven by cost/technology)
This applies to AT ECU's too. Although, i am not aware of the specific parameters that need to be learned.

2. In the Vehicle Assembly line, this correction is part of the process. The vehicles are driven on a Chassis Dyno to simulate the various load conditions. During this cycle, the closed loop parameters are programmed AND the engine/vehicle performance is monitored

- Immobilizer programming is a little different as there is a design-intent need to have unique ids. Unlike the above mentioned cases

Hence, when an ECU is reflashed, a drive-cycle with controlled loading is essential, as well as the flashing of measured parameters. These are typically possible only by specific OEM-designed tools and are not possible with the A.S.S. tools
Superb explanation sir!
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Old 11th May 2011, 08:49   #32
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Default Re: ECM changed, now what?

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Originally Posted by Jaggu View Post
Ok i think it would be dependent on the ECU being used. I came to know recently that there is a hell lot of difference between a X manufacturer and Y manufacturer ECU recently. Right from design philosophy to various parameters, how they are read and controlled.
Keeping the Petrol / Diesel ECU's aside, say for 2 Diesel engines from different manufacturers having similar Power & Emission levels, why should the design philosophy (for ECU) of X & Y manufacturers differ. I think the basic philosophy must be same, the means to achieve it may differ.

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Originally Posted by star_aqua View Post
yes, the ECU can detect it. the process is called as ZERO FUEL CALIBRATION.
Is ZFC done only for Pilot Injection? What happens in the case when an Injector starts getting old resulting in change to its response times?

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learning will not be required for those transmissions which talk to engine ECU.
Good to know. How does the ECU and the corresponding hardware change in this case? How is this achieved?

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Originally Posted by bzr77k View Post
i) by way of closed loop monitoring by the ECU itself (e.g. drive cycle),
How are the emissions taken care in such a situation or will the emission still lie within the tolerance band?

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2. In the Vehicle Assembly line, this correction is part of the process. The vehicles are driven on a Chassis Dyno to simulate the various load conditions.
Vehicles are not driven on a Chassis dyno.

Which are those vehicles using A/T's which talk to the ECU?

Spike
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Old 11th May 2011, 09:22   #33
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Default Re: ECM changed, now what?

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Originally Posted by SPIKE ARRESTOR View Post

How are the emissions taken care in such a situation or will the emission still lie within the tolerance band?
Emissions is not a concern during the drive cycle. This will typically take a few minutes only.

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Originally Posted by SPIKE ARRESTOR View Post

Vehicles are not driven on a Chassis dyno.

Which are those vehicles using A/T's which talk to the ECU?

Spike
I personally know of/ visited assembly lines where vehicles are run on a Chassis Dyno before leaving the line... Please refer to below artice in wiki which has some information on usage of Chassis Dyno for engine calibrations

Dynamometer - Wikipedia, the free encyclopedia


All OE A/Ts are designed to talk to the ECMs and the ABS (if there is an ABS in the vehicle).


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Originally Posted by vina View Post
wow man, a techy !

Another thing: tolerance is different from drift so if only tolerance were the problem then I would think a learning algorithm wouldn't be required - you calibrate once and your are good to go. For drift you'll need calibration continually. Isn't that right?
Tolerance refers to any variation from the typical/ nominal value system is designed for. This could be due to part-to-part tolerance arising out of mass manufacturing process OR temperature related tolerances OR aging (i am assuming this is what you call drift)

part-to-part tolerances can be accomodated during calibration using compensation factors
temperature related tolerances are generally not an issue as this is not very wide/ or can be compensated based on temperature sensor inputs
aging requires re-calibration or 'auto-learning' by the ECUs
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Old 11th May 2011, 09:34   #34
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Default Re: ECM changed, now what?

I am not sure I understand the whole thing, though I get the gist of it. Haven't I read somewhere that the ECU stores the data of the last six drives or so and sets the parameters for it?

@Spike
BTW how much did the replacement cost? Just curious.
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Old 11th May 2011, 10:26   #35
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Default Re: ECM changed, now what?

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Originally Posted by SPIKE ARRESTOR View Post
Keeping the Petrol / Diesel ECU's aside, say for 2 Diesel engines from different manufacturers having similar Power & Emission levels, why should the design philosophy (for ECU) of X & Y manufacturers differ. I think the basic philosophy must be same, the means to achieve it may differ.
Cost plays a major factor spikee. Complexity and functionality differ based on cost, there are many short cuts in electronics also to achieve the same results. That was my point.
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Old 11th May 2011, 11:34   #36
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Default Re: ECM changed, now what?

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Originally Posted by headers View Post
You mean a Dyno??

A very sheepish grin.

Of course that would be it. Suffering from muddled brain syndrome.
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Old 11th May 2011, 11:38   #37
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Default Re: ECM changed, now what?

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Originally Posted by bzr77k View Post

I personally know of/ visited assembly lines where vehicles are run on a Chassis Dyno before leaving the line...
That is not a chassis dyno, that is called as roller testing (purpose is different). Chassis dyno is for Emission development, DTL etc. Do you think every production vehicle undergoes emission development? No! Yes exhaust gases are analyzed for HSU in EOL testing.

Quote:
All OE A/Ts are designed to talk to the ECMs and the ABS (if there is an ABS in the vehicle).
Not sure if this is true.

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Originally Posted by Gansan View Post
@Spike
BTW how much did the replacement cost? Just curious.
Gansan, not mine. I've a RX100 only, which runs with Carburettor setup.

Quote:
Originally Posted by Jaggu View Post
Cost plays a major factor spikee. Complexity and functionality differ based on cost, there are many short cuts in electronics also to achieve the same results. That was my point.
Jaggu, tell me something which I don't know, all these are known yaar!

Spike
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Old 11th May 2011, 13:14   #38
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Default Re: ECM changed, now what?

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Originally Posted by SPIKE ARRESTOR View Post
That is not a chassis dyno, that is called as roller testing (purpose is different). Chassis dyno is for Emission development, DTL etc. Do you think every production vehicle undergoes emission development? No! Yes exhaust gases are analyzed for HSU in EOL testing.
Ah! Roller testing and Chassis Dyno are essentially the same or similar 'equipment'. The purpose, as you rightly say, is different. Roller testing is the activity performed on the equipment called Chassis Dyno. This was my understanding. The essential point here is that, there is a 'drive test' performed in the assembly line and we agree on that, so no issues
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Old 11th May 2011, 13:49   #39
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Default Re: ECM changed, now what?

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Originally Posted by star_aqua View Post
yes, the ECU can detect it. the process is called as ZERO FUEL CALIBRATION. the drift in the injectors can cause the imbalance in the power produced by individual cylinder. it is carried out during the overrun phase where the vehicle is driving the engine and no demand from the driver. a sample injections are made into each cylinder individually and the resulting change in cylinder specific speeds are compared and adjusted in order to balance the cylinders for generating equal power.
For me, this raises more questions than it answers! For another time.
If I take it that the only sensor of use for this case is the crank position sensor (no EGT sensor, EG analyser, cylinder pressure sensor/ indicator diagrams etc), how much can we glean from it for minor perturbations in input. (Am sure we can't do a major step change in the input).
Why during overrun, and not idling. (Overrun adds unknown quantity (external driving force) to the mix.)
Would love to go through the broad logic of the algorithm. And have an idea of the figures (quantitative) we are talking about.

However, this is not what I was asking Pratheesh.
What parameters are quantified in the injector code. What is their spread of values. What will be the end result (quantitatively) for this spread of values. And most importantly, why can't the exact value be detected in situ which would obviate the added step of pairing.


Quote:
regarding ATs, the calibration is required for achieving the good shift qualities which is based on the rpm and torque. the calibration is just a fine tune in case of transmission change.
for e.g if the vehicle is going down the slope, the torque is very less and shifts also should be possible at lowest possible rpm. where as when the vehicle is going up hill, the shifts should take place at higher rpms or it should not if the torque is not sufficient.
yes, learnt data can be transferred to the new transmission through tester.
learning will not be required for those transmissions which talk to engine ECU.
Once again if we are doing in car finetuning, we are expecting car to car variations. What exactly should vary? Output of the torque converter? Slippage in the brake band/ clutch packs?


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Originally Posted by vina View Post
this last bit I didn't understand at all. What do you mean by "transmissions which talk to engine ECU"
CANed.


Regards
Sutripta
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Old 11th May 2011, 15:09   #40
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Default Re: ECM changed, now what?

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Originally Posted by SPIKE ARRESTOR View Post
Jaggu, tell me something which I don't know, all these are known yaar!

Spike
Arre babaa i was sharing what i know for all You guys carry on i will watch and learn.
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Old 11th May 2011, 15:30   #41
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Default Re: ECM changed, now what?

In the Safari, whenever you change Injectors, or ECM, the service center guys need to do some "Injector Code calibration".
I don't know exactly what they do, but the task uses a laptop, and takes around 15 minutes to complete.
It has to do something with registering the electronic injector codes with the ECM.
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Old 11th May 2011, 16:29   #42
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Default Re: ECM changed, now what?

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Originally Posted by bzr77k View Post
there is a 'drive test' performed in the assembly line and we agree on that, so no issues
100 % Agreed!

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Originally Posted by Sutripta View Post
What parameters are quantified in the injector code.
Injection quantity as per manufacturing tolerance. Is the OBD level anyway involved here?

Quote:
And most importantly, why can't the exact value be detected in situ which would obviate the added step of pairing.
Question worth exploring!

Quote:
Originally Posted by tsk1979 View Post
In the Safari, whenever you change Injectors, or ECM, the service center guys need to do some "Injector Code calibration".
I don't know exactly what they do, but the task uses a laptop, and takes around 15 minutes to complete.
It has to do something with registering the electronic injector codes with the ECM.
Yes, you are right, this is called as IQA- Injector Quantity Adjustment. This means even Safari follows this method.

Spike

Last edited by SPIKE ARRESTOR : 11th May 2011 at 16:30.
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Old 11th May 2011, 18:37   #43
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Default Re: ECM changed, now what?

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Originally Posted by tsk1979 View Post
It has to do something with registering the electronic injector codes with the ECM.
It is called pairing, just like you pair your new mobile via bluetooth to your car! - the first time!

Quote:
Originally Posted by SPIKE ARRESTOR View Post

Yes, you are right, this is called as IQA- Injector Quantity Adjustment. This means even Safari follows this method.
Sir, all ECU controlled vehicles have this injector pairing - Star_Aqua: can you confirm this please.

Lets assume, this is not applicable, then how does the injector know the interval of injection? Any preset time interval from a memory location?
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Old 11th May 2011, 23:30   #44
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Default Re: ECM changed, now what?

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Originally Posted by vina View Post

For my understanding (please let me know if I misunderstood)

I'm assuming this needs to be done, because the sensors sensing the specific speeds are (relatively) slow, and unless you inject exactly one cylinder at a time, data from multiple cylinders will get averaged out defeating the whole purpose.

Only one specific cylinder will be fired per cycle(one complete firing order)

Now if that were so, then I would assume that running a cycle where such conditions (car driving the engine) are deliberately entered can help calibration - is that correct?

Yes, it helps. too long overrun will cool the cylinders and calibration will not be accurate.


also if that is the case then wouldn't the vehicle benefit the most during the run-in period? Most of the drift in many parts will happen right at that time? Kindly confirm.

yes, some conditions like idling the vehicle for some time, allowing overrun, turning key off for at least 2min without turning ON immediately, after turning ON the ignition, allowing a minute before cranking, all these will help.


Another thing: tolerance is different from drift so if only tolerance were the problem then I would think a learning algorithm wouldn't be required - you calibrate once and your are good to go. For drift you'll need calibration continually. Isn't that right?


Yes, you are right. tolerance is due to variance/deviations that caused during manufacturing and known in advance where as drift is caused due to aging.




this last bit I didn't understand at all. What do you mean by "transmissions which talk to engine ECU"
transmission do interact with the engine by sharing their status to each other via CAN. the amount of info that are shared depends on the design of gearbox and how sophisticated it should be.
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Originally Posted by SPIKE ARRESTOR View Post

Is ZFC done only for Pilot Injection? What happens in the case when an Injector starts getting old resulting in change to its response times?

ZFC is intended for NVH calibration and it is intended for determining the start of energizing for all the injections. but pilots are one which are majorly affected and main will not have much effect. for main, the balancing is affected by amount of fuel quantity.

Good to know. How does the ECU and the corresponding hardware change in this case? How is this achieved?

Spike, first lets look into how exactly the AT works. and how exactly the torque convertor works. how is the rotary pump connected and how does the turbine and impeller are matched. could you please get some info on these?


Spike
Quote:
Originally Posted by Sutripta View Post
For me, this raises more questions than it answers! For another time.
If I take it that the only sensor of use for this case is the crank position sensor (no EGT sensor, EG analyser, cylinder pressure sensor/ indicator diagrams etc), how much can we glean from it for minor perturbations in input. (Am sure we can't do a major step change in the input).

The tone wheel can be divided into segments. segment speeds can be measured very accurately by specifying start angle and stop angle.

Why during overrun, and not idling. (Overrun adds unknown quantity (external driving force) to the mix.)

Overrun is where we are sure injectors are completely shut.


What parameters are quantified in the injector code. What is their spread of values. What will be the end result (quantitatively) for this spread of values. And most importantly, why can't the exact value be detected in situ which would obviate the added step of pairing.

Code is converted into tester parameters by using a simple excel tool. i haven't checked the logic behind. lemme decode that excel sheet first.


Once again if we are doing in car finetuning, we are expecting car to car variations. What exactly should vary? Output of the torque converter? Slippage in the brake band/ clutch packs?

A new transmission on an used engine will definitely have torque mismatch which will affect the shifting quality.
Quote:
Originally Posted by headers View Post

Sir, all ECU controlled vehicles have this injector pairing - Star_Aqua: can you confirm this please.
Yes, any injector manufacturer will follow the same standards. And it is applicable for all the ECU controlled vehicles.

Last edited by star_aqua : 11th May 2011 at 23:32.
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Old 11th May 2011, 23:55   #45
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Default Re: ECM changed, now what?

I understood that the transmission and the engine communicate with each other (though I guess, when they both communicate to the ECU, since ECU is the master for both they effectively communicate to each other anyway).

What I didn't understand was what would they communicate and how does it help?

Can you throuw some light on that too?
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