Discussion in 'Technical' started by adigabnp, May 28, 2012.
with the AC off I find no difference driving linea in summer or winter
Agree to all of the theoretical explanations that you have given.As you have mentioned, it is indeed true that contrary to what should happen theoretically, in reality something different happens.
Let me give you an example, When we use forged pistons in an engine, the piston to wall clearance is deliberately kept on the higher side because forged pistons tend to expand differently compared to cast pistons. You can say that they expand a bit more. Therefore, during a cold start, in certain engines (Read: ones with forged pistons) you can hear a little bit of piston slapping. The reason for this is pretty obvious. During a cold start, the clearance is more but once both the block and piston start expanding, the clearance reduces and stop the slapping. Therefore, once the operating temperature is reached, the piston slapping stops and you do not hear the noise anymore.
If what you said would be truly happening, then all engines irrespective of petrol or diesel, NA or Turbo would be burning oil like crazy. Does that happen ? I am sure you will agree that this doesn't happen. Why ?
My point is, whatever points you have put forward are completely true and I don't differ on that but the fact is the same logic or theory cannot be applied everywhere even if we are talking about the same phenomenon.
After so many decades and spending god knows how much money till date, auto companies along with component makers must have studied all these phenomenon and although they cannot change the characteristics, they can definitely find a way to make sure these characteristics do not hamper the normal functioning or more specifically affect performance.
Atmospheric changes are I guess even more difficult to guess and this makes tuning an engine becomes even more difficult. Therefore the ECU mapping is done keeping in mind most probable conditions and keeping a good safety margin for corrections depending on the variations.
I know what a MAF sensor does.
You have yourself clarified what I have been trying to say. Depending on the variations in the air inflow characteristics, the ECU adjusts the fuel inflow to maintain the AFR. So it is but obvious that in some cases, the ECU might reduce the fueling, right ? Therefore in a nutshell, less fuel and air going in = drop in performance ?
An engine is nothing but an extremely complex and sophisticated air pump. Everything revolves around how you manage to get the air in and out. The more you can manage to get in in a given period of time and manage to take it out equally quick, you make good power. One of the key elements in any ECU map is something called volumetric efficiency. I guess whatever I said above should pretty much explain what VE refers to. Every tuner has a basic goal of attaining maximum VE which translates into power.
I guess that explains that performance variation does not revolve only around metal and alloys, their characteristics, their variation in characteristics with respect to temperature and so on.
I mean no disrespect to you Sir but from the statements that you have made, you seem to think that ECU is just like any other component in the car, is it ? If yes then I am sorry but you are sadly mistaken. Whatever performance you see in modern engines, most of the credit goes to ECU because over the period of time, the basic functioning of an internal combustion engine hasn't changed drastically, has it ?
In the non ECU era, did you have such efficient engines ? No. Turbocharging changed the game, improved efficiency drastically. What was it that adjusted the fueling with so much air being dumped in? it was the ECU.
ECU is not the only component that makes modern engines so powerful and efficient BUT it definitely is the most critical component,without which the engine wouldn't work at all.
Also ECU tuning is no joke.With so many sensors providing so much data and mind you, almost all the values are variables. With so many variables, the permutation combinations become mind numbing. Attaining a perfect balance of power, efficiency is a much more painstaking task than you think.
Why do you think serious tuners in Europe or US charge a bomb for tuning ? Think about it.
Exact same rules of physics and same mathematics are working in this situation you explained. In the case you explained engine block has lower coefficient of expansion and the piston has higher coefficient of expansion. Naturally piston expands more and the clearances come down. If it is so easy to fix the problem engine manufacturer would have fixed it. Unfortunately it is not so easy to work against rules of physics and material properties. Either the manufacturer was unable to avoid piston slapping or has decided it is not worth investing time and money on fixing an issue which lasts only for few seconds of starting the engine. Who knows - tt may even be deliberately designed that way to avoid piston getting stuck in the engine cylinder because it expands more than the engine block when heated up.
I am not at all saying ECU programming or tuning is a joke. I know little bit about the complexity of ECU because I know a friend working on engine control program for a well known ECU manufacturer in Europe. Apart from friend he was a colleague too. Therefore have seen him sitting with a complex unit having so many sensors and wires hooked up all over the place. As much as I have heard from him no doubt it is a complex system. But being a programmer for last 15 years I can tell for sure programming is a much easier task than fighting against physics and material properties. When I am working on a program I can see the effects of the changes I make within seconds or worst case few minutes. If I suspect something is not working as I expect I can just fire up the debugger and stop the execution to see exactly what is going on. When I am in debugger I can on the fly change the values and influence the program behavior to see what happens. None of these exist when a mechanical engineer is working with physical components. He has to design, machine it and then put it in an engine to see what happens. It takes days/weeks/months to do one trial run. Several things don't go as expected. Then follows lot of guess work and experiments to understand what may be happening and how to fix the problem. One can imagine which one is more complex and expensive (money and time) to work with - ECU or mechanical components.
Please don't measure real value of something by the cost. Cost is driven by perceived value, demand supply gap, glorification etc. Consumers are willing to pay any price when they are made to believe it is rare, not because it is really rare. Best example is aluminium - it was the most expensive metal in 18th century. It is one of the cheapest today. Days of ECU tuner's supremacy will be gone soon after auto manufacturers come together to announce universal and public standard for engine and ECU interaction (it is not a quesetion of if it will happen, it is only a question of when it will happen). When that happens to ECU we will see a ECU revolution. We will have several ECUs, ECU control programs to choose from, load it into ECU and even tweak it ourselves Just like a computer mouse, mouse driver and computer interaction we see today. You may feel I am day dreaming, I don't mind. Dreams are necessary to have hope in life. I hope ECU revolution will happen in my life time when I am young enough to try it on my car!
I will rest my case here!
Start out with smaller things to check out.
0. If your car is giving required milage theres nothing much to be alarmed about
1. Wheels might be in need of Allignment / Balancing. A tough demanding trip to a hill station or even plains can take a toll on the Wheel allignment.
2. Check out if the power steering needs some attention. That could make u feel heavy too.
3. Tyre pressure might be low or uneven .
4. Other technical issues are anyway mentioned in this thread by other TFI members....take asecond opinion from a gud mechanic in ur city.
Thanks for all your feedback and suggestions.
I had been out of the country for a month and did not drive my Punti for this duration.
My Punti was drove by a friend of mine, occassionally.
After a month, when I drove her, I am surprised that there are no "heavyness" issues!!!
I am not sure which of the following factors "really" influenced this change.
1. The refuelling has happened in reliable fuel stations in the last month.
Is it the fuel? I am not sure.
2. In the past month, the weather changed from "hot" summer to "cool" monsoon.
3. My friend shifts gears at very high RPMs, always above 2000RPM.
I am not sure if it does make any difference et all!!
4. Last, my perception might have changed since I didn't drive Punti for the past month.
Anyways, thanks for all your inputs.
Need to have an "eagle" eye to identify further which of these is the real reason!!!
Good to know that..Correction..it's Punto and not Punti..
Arnav, I call my dear one as "Punti"...
i too feel the heaviness after second service.. before giving my car to service station it has good pick up and highway mileage of 21 but after service i got bad pickup and mileage of 26.6 on highway.. do i need to check with the software or any tuning is required ???
I was feeling erratic heaviness in my Linea MJD and more after AC being switched on.Its completely gone after TURBO was replaced although i also got the timing chain replaced and got EGR cleant.Erratic power issues may be related to Turbo issues but its too early for you for EGR cleaning/Timing chain.I got the TURBO replaced at 63500 Kms.
Bad pickup & high milege of 26.6 means car is running on lean mixture due to turbo related problem. Many time MAP sensor doesn't get proper boost so ECU injects less fuel,car runs on lean air/fuel mixture. So we get abnormal high milege but poor pickup.
Signals of sensors are at borderline of emergency. So we don't get any ecu error. At this time we can't prove problem of poor performance but no ecu error. That,s why Tata ASS certify car is fine & they get success to avoid expensive warrantee claim.
As engine has computerised control engine management system,we can,t tune it like old generation carburetted engines.
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