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Old 14th October 2013, 22:50   #46
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Default Re: Engine Idling Problem

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Originally Posted by DerAlte View Post
The ECU is not "programmed to accept lower rpm" - it is programmed to take appropriate action at different RPM. Incase of AC coming on, it increases the injection to take care of increase in load.

Correct, but an ECU is programmed to behave like that from start, it is not 'reprogrammed'.
I accept this but I have doubts on the functioning and the wear and tear that could cause with this setting that is seen on this WagonR.

Will the load added onto the engine it must be rotating at a higher RPM to compensate for that load rather than a lower RPM causing the engine to lug! Is it OK to run the engine with such settings?

I did check in my dad's SX4. The RPM was 850 at idle and when the AC was switched on the RPM first dipped to 735 and after a second it went to 918 and was stable there on (910-930 RPM).

And is it possible for MASS to reprogramme or change the setting's of the ECU now or does this have to be done at a tuner's place?

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Sorry Guys being a newbie all my posts are posted only after being approved by a moderator and hence I cannot participate in real time.
Any update on the issue?

Anurag.

Last edited by a4anurag : 14th October 2013 at 22:51.
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Old 15th October 2013, 09:58   #47
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Default Re: Engine Idling Problem

Quote:
Originally Posted by DerAlte View Post

The ECU is not "programmed to accept lower rpm" - it is programmed to take appropriate action at different RPM. Incase of AC coming on, it increases the injection to take care of increase in load.

Correct, but an ECU is programmed to behave like that from start, it is not 'reprogrammed'.
I would beg to differ on the ECU behaviour. Afaik ECU does not have AI and can only stabilise the car based on the parameters and directions programmed in it. For example a typical wagon r has a DESIRED IDLE WITH AC ON programmed at 847 and ECU will only try to stabilise the idle rpm nearer to that irrespective of whether the engine is knocking or vibrating.

Also pls note that in wagon r cng the ECU is programmed in such a manner that it works to stabilise the idle rpm as 847 with AC ON and 878 with AC OFF resulting in shuddering of engine.


And as for the reprogramming new tolerance limits can be set in the ECU which will accept higher rpm is the case of AC LOAD SWITCHED ON.
@ Anuraag

No reply as such from Maruti and I hope you got the mail which I forwarded to you, what's ur opinion.

Again trying to attach screenshot of the obd reading which will be self explanatory as to what anomaly I am trying to point out.
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Old 15th October 2013, 10:55   #48
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Originally Posted by a4anurag View Post
... I have doubts on the functioning and the wear and tear that could cause with this setting that is seen on this WagonR. Will the load added onto the engine it must be rotating at a higher RPM to compensate for that load rather than a lower RPM causing the engine to lug! Is it OK to run the engine with such settings? ...
DNU what 'wear and tear' you are referring to! Lugging? No, not at all. The dip lasts for less than a second before increasing to the higher value. It is just about as long as it takes for the ECU to sense the dip by sensing crankshaft deceleration. Not long enough to be associated with 'lugging'.
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Originally Posted by a4anurag View Post
... I did check in my dad's SX4. The RPM was 850 at idle and when the AC was switched on the RPM first dipped to 735 and after a second it went to 918 and was stable there on (910-930 RPM). And is it possible for MASS to reprogramme or change the setting's of the ECU now or does this have to be done at a tuner's place? ...
Why does it have to 'reprogrammed'? Not required at all. Please don't think empirically for these issues - the designers have done a very decent job originally. You and I are not required to do auxiliary thinking and influence.
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I would beg to differ on the ECU behaviour. Afaik ECU does not have AI and can only stabilise the car based on the parameters and directions programmed in it. ...
Sir, I think it will do your understanding a world of good if you read up on implementing algorithmic control systems programming in embedded systems. What you think is AI is actually fairly straightforward control systems implementation in software. About 30 years old at that - won't need any changes in the foreseeable future. The subject itself is more than 100 years old!!! Post-facto observation of data coming from instrumentation is an incorrect method to infer anything about programmed behaviour. The idle RPM is a notional value (not set as an absolute RPM figure to be achieved under any circumstances). Based on inputs such as air pressure, various temperatures etc. the idling fuel injection control loop adjusts the fuel injection where the engine is neither accelerating nor decelerating with no load, i.e. it is in a stable operational state. You are seeing it as a number and speculating on the programmed behaviour. It doesn't occur to you that the same engine would settle to a different idle RPM value at sea level, respectively in Ladakh - never requiring any reprogramming by MUL.

Last edited by DerAlte : 15th October 2013 at 10:56.
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Old 15th October 2013, 20:11   #49
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ISir, I think it will do your understanding a world of good if you read up on implementing algorithmic control systems programming in embedded systems. What you think is AI is actually fairly straightforward control systems implementation in software. About 30 years old at that - won't need any changes in the foreseeable future. The subject itself is more than 100 years old!!! Post-facto observation of data coming from instrumentation is an incorrect method to infer anything about programmed behaviour. The idle RPM is a notional value (not set as an absolute RPM figure to be achieved under any circumstances). Based on inputs such as air pressure, various temperatures etc. the idling fuel injection control loop adjusts the fuel injection where the engine is neither accelerating nor decelerating with no load, i.e. it is in a stable operational state. You are seeing it as a number and speculating on the programmed behaviour. It doesn't occur to you that the same engine would settle to a different idle RPM value at sea level, respectively in Ladakh - never requiring any reprogramming by MUL.
Wow wish I had joined this forum earlier, so much to learn. And my sincerest apologies if I offended you in any way. Please note all my below beliefs have a preassumption that the engine is fine tuned and all the mechanical/electrical /electronics parts and sensors are working perfect and the below scenario discussed applies specifically to idling. I was looking at it in a more basic manner and will postulate my logical reasoning and would really appreciate your comments and advice if they are technically wrong as in the end I understand we both are working to try and solve the same problem which is why my wagon r cng shudders at idling with ac on and it is more pronounced when using petrol as a fuel. 1. Lower the rpm, lower the engine capacity to take on loads. 2. Engine will shudder and/or vibrate when the load taking capacity of the engine at that moment is lower than the load. 3. Increasing rpm will increase the capacity the engine to take on extra and thus eliminate the vibration and/or shudders. 4. ECU does not have load sensors and cannot determine how much load is connected. 5. When ac compressor switches on it increases the load on the engine. 6. ECU will try to stabilise the idling rpm based on the preprogrammed setting of desired idle value naturally taking in other parameters one of which is altitude and the lack of oxygen in the air. So now my simple query is why is the ECU programmed to try and stabilise the idling rpm AT A LOWER RPM with an AC compressor load connected?

Last edited by DerAlte : 16th October 2013 at 14:09.
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Old 16th October 2013, 17:15   #50
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... Please note all my below beliefs have a preassumption that the engine is fine tuned and all the mechanical/electrical /electronics parts and sensors are working perfect ...
If the engine is exhibiting unusual behaviour, the above would be an incorrect assumption, right? Something or the other must be out of kilter, absolutely or relatively?

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... and the below scenario discussed applies specifically to idling. ... why my wagon r cng shudders at idling with ac on and it is more pronounced when using petrol as a fuel. ...
The shuddering when idling has a different origin

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Originally Posted by Ageing Stud View Post
... 1. Lower the rpm, lower the engine capacity to take on loads. ...
One should refer to Torque-Speed curve
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Originally Posted by Ageing Stud View Post
... 2. Engine will shudder and/or vibrate when the load taking capacity of the engine at that moment is lower than the load.
Not necessary. At idling the loads are very small. 'Shuddering' is different from 'lugging'
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Originally Posted by Ageing Stud View Post
... 3. Increasing rpm will increase the capacity the engine to take on extra and thus eliminate the vibration and/or shudders. ...
Yes, but ...
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Originally Posted by Ageing Stud View Post
... 4. ECU does not have load sensors and cannot determine how much load is connected.
ECU cannot *measure absolute load*, but it definitely *sense* load coming on or going off. No magic here, just some plain old physics & maths
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Originally Posted by Ageing Stud View Post
... 5. When ac compressor switches on it increases the load on the engine.
Correct
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Originally Posted by Ageing Stud View Post
... 6. ECU will try to stabilise the idling rpm based on the preprogrammed setting of desired idle value naturally taking in other parameters one of which is altitude and the lack of oxygen in the air. ...
"Stabilises idling". Not the same as "stabilize idling rpm"
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Originally Posted by Ageing Stud View Post
... So now my simple query is why is the ECU programmed to try and stabilise the idling rpm AT A LOWER RPM with an AC compressor load connected?
:O You must have missed something somewhere - when did anyone say that? I thought everyone said:
* AC comes on and loads the engine
* Additional load reduces RPM
* ECU increases injection and air to increase RPM
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Old 16th October 2013, 19:21   #51
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Default Re: Engine Idling Problem

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Originally Posted by DerAlte View Post
If the engine is exhibiting unusual behaviour, the above would be an incorrect assumption, right? Something or the other must be out of kilter, absolutely or relatively?

"Stabilises idling". Not the same as "stabilize idling rpm"
:O You must have missed something somewhere - when did anyone say that? I thought everyone said:
* AC comes on and loads the engine
* Additional load reduces RPM
* ECU increases injection and air to increase RPM
Sir, what now I want to understand is what is the function of the parameter' Desired Idle ' programmed in the ECM and please note that I am talking about idling rpm in 2 basic scenarios one with the ac load connected and the other without the ac load.
Correct me if I am wrong, isn't it the rpm value which the ECM should try to maintain?
My only thought is that when everybody including yourself are saying ECM SHOULD INCREASE RPM WHEN IT SENSES AC LOAD, then why is Maruti programming wagon r ECM in such a way that it is designed to reduce rpm when it senses ac load.

CHECK OUT SCREENSHOTS ATTACHED BY ME A FEW POSTS BACK.

Also when I asked Maruti technician to increase the desired idle value from 847 to 900 with the ac switched on, the ECM increased the rpm immediately and the engine became smooth. Problem is mass technician cannot reprogram the ECM and whatever they do with their diagnostic tool is temporarily implemented till the time the tool is connected to the car so that's why I am after MUL to reprogram my ECM and they are giving me bs.

I am sure there will be other wagon r 2013 model owners here on the forum, can somebody go to the mass and ask them to use their scanners which they call tech tool to read desired idle values with and without AC.
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Old 16th October 2013, 19:36   #52
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Default Re: Engine Idling Problem

Quote:
Originally Posted by DerAlte View Post
One should refer to Torque-Speed curve
Quote:
Originally Posted by Ageing Stud View Post
1. Lower the rpm, lower the engine capacity to take on loads.

2. Engine will shudder and/or vibrate when the load taking capacity of the engine at that moment is lower than the load.
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Just did a google search for the following figures. It is evident that the Torque during idle RPM is decently high enough for the engine not to lug.

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Originally Posted by Ageing Stud View Post
Sir, what now I want to understand is what is the function of the parameter' Desired Idle ' programmed in the ECM
Quote:
Desired Idle RPM-Drive (or target idle)
The Rpm that the ECU is trying to reach but has to modify things like the ISCV and fueling to reach until the car has reached operating temp. At this point the Car Will idle (stock cammed anyway) at the desired rpm target fairly easily.
Source: http://evoecu.logic.net/wiki/ECUFlash_Specific_Glossary

Anurag.

Last edited by a4anurag : 16th October 2013 at 19:44.
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Old 16th October 2013, 20:39   #53
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Originally Posted by Ageing Stud View Post
... isn't it the rpm value which the ECM should try to maintain? ...
More or less, yes. That is the target idle RPM - a notional value. Depending on load and other conditions, the actual idle RPM (stable idle) would be +/- 50RPM or so.

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Originally Posted by Ageing Stud View Post
... My only thought is that when everybody including yourself are saying ECM SHOULD INCREASE RPM WHEN IT SENSES AC LOAD, then why is Maruti programming wagon r ECM in such a way that it is designed to reduce rpm when it senses ac load. CHECK OUT SCREENSHOTS ATTACHED BY ME A FEW POSTS BACK. ...
Your screenshots are fine, your inference is wrong. Even Wagon R increases RPM. Where you are making a mistake is in observing cause and effect. You have to relate it to the short and long term fuel trim at the bottom of the screen. What you are failing to notice is that the Target Idle RPM is a dynamically computed number, not a static number entered by a person. Approaching from a higher RPM the idle rpm target is gradually brought down (see Pic 1). If this is not done, the engine will undershoot and quite likely stall.

Quote:
Originally Posted by Ageing Stud View Post
... Also when I asked Maruti technician to increase the desired idle value from 847 to 900 with the ac switched on, the ECM increased the rpm immediately and the engine became smooth. Problem is mass technician cannot reprogram the ECM and whatever they do with their diagnostic tool is temporarily implemented till the time the tool is connected to the car so that's why I am after MUL to reprogram my ECM and they are giving me bs. ...
Sorry to say but ... I think you should let them be. They know what they are doing - which under the circumstances is very appropriately 'NOTHING'. The same can't be said for you, since you are using empirical logic without basis or understanding.
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Old 29th May 2016, 00:46   #54
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Default Re: Engine Idling Problem

Grand i10 Petrol Automatic (4 speed torque converter), 9,000 KM run, 1 year, running on synth oil post first service.


I have been facing an engine idling problem past ten days. Using the AC on idle engine speed makes the engine speed (and RPM) fluctuate.

The sound outside the cabin due to this problem is also very noticeable.

Here is the video of the RPM needle: See post 00:07 in the video:

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