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Tunning of Multijet diesel engine

Discussion in 'Engine Compartment' started by bhai, Apr 1, 2014.

  1. asimpleson

    asimpleson Esperto

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    I was trying to comprehend what mistake I had done by mentioning Power to Weight ratio here. The whole idea of mentioning it is to make a case why performance issues are not as pronounced in Swift/Dzire or Vista/Manza as they are in Punto and Linea. You are mentioning the same point again. The definition of power to weight ratio and by logic where I have used looks pretty apt to me. I have gone through my post again couple of times and cannot see anything to be interpreted loosely. I meant what I said and stand by my views which make sense from all the real world aspects if you care to see closely. Please dont take it the wrong way, but some parts of the explaination still don't make me understand the relevance to core issues at discussion here; atleast to my point of view or the fallacy or falsity thereof if any in the first place.

    I am not willing to make generic comparison between the engines or it's built qualities with regards engine block and head etc. since it served no point given that most are manufactured at Ranjangaon, Pune. The fuel injection systems used however, the ECU that controls it, the performance mapping there is to the cars and the power to weight ratio, all are or could be tipping to make a car like Swift DDiS more zippier to perform (arguably at that again).

    Honestly, the figures about gear ratio are good for this discussion, but again you see if you read the first post you will find the discussion is about performance issues without ECU errors. Gear ratios as you mentioned will have effect in everyday drives. Agreed. But Bhai is talking of performance drop without ECU. That performance which was adequate otherwise, given the gear ratio pro and cons.

    Palio MJD, for example can beat the Swift and provides some exhilarating performance as per people I have had feedback from. Did it have similar or different gearing ratios and where it lacks against Punto is another topic which might give us better angles to look at this problem.

    Again to summarize, Bad fuel, particles in fuel supply lines, Injector clogging, bad engine oil, Clutch problem, rusted wheel bearings, Fuel pumps, EGR (an eyesore for many as will be evident from queries on EGR and aptly mentioned by Gurjinder) and gear ratios (mentioned by yourself). A few or many of the above in conjunction with each other lead to issues that cannot always be picked up by the ECU.

    - - - Merged Post - - -

    Bhai, why not see MJD vs DDiS or Quadrajet? Your friends are right I say if you compare with other manufacturers also. :D
    Your point is why Fiat cannot see the issues that effect engine performance. I agree with it. And that is why you see I support your friends' view who think you like to compare MJD with DDiS and Quadrajet. Let them think about it and you ask them what makes their cars if they own Vista or Swift DDiS perform without deterioration.

    Bhai with regards EGR I have cited somewhere from an article when EGR get clogged as per expert opinion, not mine of course. While bad quality fuel is responsible. There maybe other reasons also which you will need to rule out.

    Right now what is the status of this problem of yours. What is the opinion of FASS about the same. IIRC, you got whole lot of things changed under extended warranty recently right. What according to you was the culprit and does it perform better now. Do post your finding for us to be careful about in the future.
    Last edited: Apr 10, 2014
    1 person likes this.
  2. GP_Freak

    GP_Freak Amatore

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    ^ The Thread should be Titled as Performance issues with "MJDs in Certain Linea and Punto" or "Performance issues with my Linea/Punto"

    i would classify most of them as Quality problem or even design issue ( what we call as design issue could be the intended desing by the engineers too for another reason)" bad engine oil, Clutch problem, rusted wheel bearings, Fuel pumps"

    So now, we can talk about the specific problem what Bhai is facing in his Punto
  3. asimpleson

    asimpleson Esperto

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    Bad design can be a deep rooted problem and can plague an entire generation of engines of that class irrespective of where they are manufactured. Quality on the other hand is a product of manufacturing techniques and materials used along with skill sets to name a few issues that can affect it. In the case of the MJD it was the best engine at the time it was selected by International tests and standards. So the design of the engine could not have been so bad, on the contrary I believe it is a very good engine, albeit lesser know perhaps due to it's age.

    If engineeers intend a thing in design for one reason and if affects some thing else to compromise it, it is still a bad design as far as the end-user is concerned. A design that is based on compromises is a compromised design or simply said, passable by some measures but not good enough nonetheless.

    Bhai has implied in all his posts that Fiat should tune their engines (MJD in this case) such that they perform even with low or bad quality of fuel of India, how bad? As bad as that tolerated by DDiS and Quadrajet, right? See there, we have other MJD engines coming into picture again ! :)
  4. livelyyoungman

    livelyyoungman Regolare

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    But is it not that the DDiS is a 75HP FGT engine? That makes a world of difference.

    Have anyone tried the 90HP VGT Vista or SX4? I can say SX4 Diesel has similar lag. So I believe that is the basic difference.

    Gurus please confirm
  5. GP_Freak

    GP_Freak Amatore

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    All designs are compromised in one way or the others unless they have an unlimited budget. Even with an unlimited budget, they may need to compromise on certain factors due to laws of physics. ex: Power and Fuel economy are inversely proportional. Similarly, power and fuel quality are directly proportional. If we want to tune the engine to higher power, then we will need a better quality fuel. If its a Gasoline engine, we need to have higher Octane Rating for high power engine as it drastically affects power output., If its a diesel engine, it can be countered by increasing the compression ratio and fuel injection pressure. But, the more serious problem comes with particles in the fuel and it affects the injectors big time.

    so engine needs to be tuned down, say the nozzle orifice size and injection pressure.

    OK, to have a more fruitful discussion, we can isolate a couple of fiat vehciles facing this unique problem and analyze is in details may be., This sure looks like an intersting topic for me, but a painful one for the owner of the vehcile. We could list various factors which might affect the performance of the vehcile to start with i guess ?

    @livelyyoungman - This is not about poor pick up in General.If so the the comparison as suggested by you will the first thing to be done. Its that they are facing sudden poor performance from the normal value the fiats used to operate in a normal day. So we may not even compare it to another car, we need to compare it to a 90 BHP Fiat without problem and 90 BHP fiat with this unique problem like what Bhai is facing.
    Last edited: Apr 11, 2014
    1 person likes this.
  6. asimpleson

    asimpleson Esperto

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    @GP_Freak,

    Arguably, some of the best designs and inventions came into being with meagre resources and out of garages or even a brain wave. Ingenuity is all that counts to come up with better solutions using next generation technology or a culmination of old age and new age technology. We could well keep the real world financial aspects out of this discussion for it's benefits and efficiency could be anything based on pure speculation and will add more to the confusion on this topic.

    Both Spark and CI engines for a long time have fundamentally been operating on their respective principles with advancements moreso in the way the air and fuel delivery and control mechanisms improved in a more direct and indirect ways. What is a good design then as far as engine is concerned?
    A good design crudely put in this case is one that can provide good power-pickup-torque across the RPM range, efficient in burning, minimizes carbon emission out of the box, and with reduced heat and frictional losses and so forth.

    To the main point of discussion; An engine should not be made as per the fuel conditions (bad fuel conditions), but the fuel should be formulated as per greener emissions as per best practices internationally. Adjusting to adultrated fuel means we should rather use NA engines which could probably be more tolerant to higher sulphur-kerosene or Naphtha adulteration as in gasoline engine is a move in the negative direction.
    1 person likes this.
  7. GP_Freak

    GP_Freak Amatore

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    Comparing Hardcore auto enthusiasts team to Profit oriented organizations are different. If compared, it will add to confusion. It was my response to your comments on design. Not sure what is your line of work, but engineering thumb rule is all desings are compromised for various factors That is why we still have tolerances :). We are real world people and talking guess there is nothing wrong in using real world financial aspects because, Nothing is for free.( including my fiat )

    This is not clear. This could be interpretted or debated in thousand ways. When fiat linea came with low ground clearance, what was the reaction of the public? Were ppl asking for better roads to government or blaming fiat for not designing a vechile which doesnt scrape its underbody.( fiat had to compromise again for local needs by raising the clearance and thus affecting the CG)
    So another engineering thumb rule is, specs changes as per operating conditons. That is why we always used to get detuned engine in India.

    Remember Skoda Fabia inital lots had huge problem ? It was because of the fuel conditions in India.Simply put,the engine was not tuned for Indian fuel conditions. Now the fuel quality has improved a lot, but still not on par with other countires. That is why noways not much detuning happens for India. So dont worry about having to drive a NA DI Diesel
  8. GP_Freak

    GP_Freak Amatore

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    ^ sorry guys, didnt check the typos as didnt have much time. Now couldnt edit :(
  9. asimpleson

    asimpleson Esperto

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    GP_Freak, if you re-read my post you will understand that I have been trying to suggest that in order to draw certain technical conclusion or pin focus on pure technical aspects, sometimes financial aspects could be discussed less about. Why? Just so that our discussions dont go about round and round with too many topics intersecting each other, for the sake of clarity. For every argument there could be a counter argument, always. Clearly new points can be drawn and every word can be disected for critical anaysis by yourself. Who am I to say otherwise? All I am saying is we are deflecting from the main topic in focus here.

    It makes me sad to say but your overstating of facts which I already know about design and many other aspects, does not contribute to this thread. I am sure you might feel the same way. Lets be matured and not engage in rounds of disagreement henceforth.

    In a very early discussion in one of my posts I have said that argument for the sake of arguing will lead to chaos on the thread. And I am afraid we are already again down that path. Seriously my way of thinking is to take it or leave it. If you disagree again and again and I can cleary see you pretty much do disagree many a things I suggest, then kindly lets move on and lets not keep engaging in discussions for the sake of this Forum.

    So that means we as people are moving forward or backward? Bad roads will become worst and Adulteration will go from bad to worst, how far do you propose we change specs as per operating conditions? I am sorry I sound sarcastic to you, but these are hard questions we need to ask ourselves as citizens of this country.
    Should roads improve so that we take advantage of lower GC or should we mess up our roads so that companies can change specs and we invoke engineering thumb rules to take a step in the negative direction? You are actually proving my earlier point here by stating the GC kit point. Again just search the forum and see how many people like the old lower CG as you mentioned, but where are the roads. So for one car a different suspension for UK, another for Turkey, yet another for Brazil and another of Egypt and another for India. Don't you think Fiat would rather build just one that fits most. If we have messed up our roads, and we blame Fiat, it's not fair. I am proud of Fiat that it offered an update when people had problems on wrongly sized speed-bumps and pot holes.

    Again, Fuel quality should be improved and engine not detuned is what I am saying in the earlier post, that's precisely what I implied. Surely you will disagree again for me wanting us to go in an ideal direction. Why do we keep debating like this here? To what end.

    Yet again GP_Freak, your comments are upsetting. :( Who is worrying here about going back to NA DI Diesel? Definitely not me. Please re-read my earlier post my friend.

    I am now saying that if we are to go de-tune engines (hypothetically) then might as well we use NA Diesel tech, atleast we can stop complaining about Fuel Adulteration. A step that would be in negative direction as I suggested earlier. (that's sarcasm/criticism again to our people's wrong doings and definitely not to yourself).

    I am really not aware of Skoda Fabia's initial lots problem with fuel conditions. In good faith if that was the problem as you suggest, then it's our fault as we loose to gain performance and reliability and Fuel efficiency and best possible low emissions from a fantastic car like the Fabia. Again do I need to state the obvious. We the end users loose the most, not the car manufacturer, nor the government treasury(definitely not as much as us). The only way is to move forward with international best practices and standards.

    PS.: BTW, I also do drive an NA Diesel car pretty often and it returns a healthy mileage and power and decent driveability, but that's besides the main point here.
    Last edited: Apr 11, 2014
    1 person likes this.
  10. GP_Freak

    GP_Freak Amatore

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    ^ Brother, i am not side tracking this conversation. Please understand if you can stick to the topic, then i too can. Yes, if you are that sarcastic, then you should get all fired up when companies advertise " Designed for India", which means we are getting a car which is tuned for Indian operating conditions.

    Again, its up to you to take what you want. Engineering thumb rule applied every where and including the companies looses out if it doesnt include it. Companies dont care what this meager online polulation likes, Its the common public who make the sales and not forums. So stop refering to these online comments and group to reality. Common man wanted a car which doesnt scrape and Fiat reponded with one in LINEA. Why did FIAT choose to backward and not forward then ?

    You still debate about the requirement of good quality fuel, but what is the point if you keep wanting for it in TFI ? It will still stay in these forums archived for years. Get in touch with superbike owners or guys having imported cars, they will tell you their plight of running behind high octane fuel. Ideality is a dream, but the current situation is what you need to tackle. What is needed is realism and not idealism. If a dose of reality is needed, i would advise you to talk to Bosch technical team to understand the quality fo fuel in India.


    I have not seen much technically valuable post in this thread and guess i better drop out of this thread as i can see this not going any where.
    Last edited: Apr 15, 2014

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