Go Back   Team-BHP > Under the Hood > Technical Stuff


Reply
 
Thread Tools Search this Thread
Old 4th September 2010, 10:14   #16
BHPian
 
Join Date: Feb 2009
Location: Chennai
Posts: 633
Thanked: 624 Times
Default

Even my Punto exhibits a different character daily. Sometimes it is butter smooth when the weather is cold and as the engine heats up it becomes a bit raucos(not of the extreme kind), sometimes the second gear gives a lot of range and sometimes it becomes very short, sometimes the turbo lag gets more pronounced and sometimes it becomes almost non-existant.

I think Multijets' behavior is a lot influenced by the external temperature.
Experts must be able to tell why it is so.
CliffHanger is offline   Reply With Quote
Old 4th September 2010, 11:49   #17
Newbie
 
Join Date: Aug 2010
Location: Delhi
Posts: 22
Thanked: Once
Default

Yes cliffhanger, thats exactly how my car behaves!
fink_ployd is offline   Reply With Quote
Old 4th September 2010, 12:33   #18
BHPian
 
ragzv's Avatar
 
Join Date: Oct 2007
Location: Kolkata
Posts: 107
Thanked: 8 Times
Default

During cold starts the ECU feeds a much richer air-fuel mixture to the engine till the time its reaches its optimum temperature.

This though marginal, may give a feeling of better power during warm-up
ragzv is offline   Reply With Quote
Old 4th September 2010, 12:53   #19
BHPian
 
lambdaplus's Avatar
 
Join Date: Aug 2010
Location: Bangalore
Posts: 38
Thanked: 38 Times
Default

Quote:
Originally Posted by fink_ployd View Post
Yes, im guessing the same thing as i have noticed it mostly in the mornings.
Uh, isn't it somewhat how a cold air intake works?
Similar, yes! But not entirely!
Early mornings means the entire air everywhere is cold. Hence better "air-charge". However, cold air intake lets in relatively cooler air. Generally the stock air intake is placed near the vicinity of the radiator, or sometimes even behind it! This means, the air coming in is heated by the radiator. Now, if we have a mechanism to take air before the radiator or anyother heat source, we get relatively cooler air. Hence the name cold air intake. Early morning is best cold air intake possible

Quote:
Originally Posted by CliffHanger View Post
Even my Punto exhibits a different character daily. Sometimes it is butter smooth when the weather is cold and as the engine heats up it becomes a bit raucos(not of the extreme kind), sometimes the second gear gives a lot of range and sometimes it becomes very short, sometimes the turbo lag gets more pronounced and sometimes it becomes almost non-existant.

I think Multijets' behavior is a lot influenced by the external temperature.
Experts must be able to tell why it is so.
Yes, in terms of diesel cars, there are lots of components like Turbo, intercooler, radiator. All these perform very well when ambient temperature is low. Hence an increase in air charge, hence better feel.

Quote:
Originally Posted by ragzv View Post
During cold starts the ECU feeds a much richer air-fuel mixture to the engine till the time its reaches its optimum temperature.

This though marginal, may give a feeling of better power during warm-up
True Ragzv. However this is the case for Petrols only.
Diesels never run rich! They are always on the lean side. The richest they can get is still on the lean side - say a lambda value of > 1.5 (1 being optimal, < 1 being rich).
lambdaplus is offline   Reply With Quote
Old 4th September 2010, 13:19   #20
Senior - BHPian
 
Shan2nu's Avatar
 
Join Date: Feb 2004
Location: Hubli - Karnata
Posts: 5,525
Thanked: 87 Times
Default

The feeling of better response when cold is only upto a certain rpm range. If you were to race a cold engine against a warmed up engine, the latter would be more responsive everytime.

Anyone felt the diff in the response after a track session? The engine just goes crazy.

Shan2nu
Shan2nu is offline   Reply With Quote
Old 5th September 2010, 23:18   #21
BHPian
 
Join Date: Oct 2007
Location: hyderabad
Posts: 229
Thanked: 41 Times
Default

Hi fink_ployd,

Even my 2 year old Indica V2 (DLS) behaves the same way. The engine makes less noise and sounds very smooth, accelerates fast in early mornings and nights (when the temp needle does not reach till middle). I did not bother about this issue as there seems to be no problems till now with this behavior :-)

Thanks,
Srinivas.R
sriswe is offline   Reply With Quote
Old 13th September 2010, 18:40   #22
BHPian
 
Jomz's Avatar
 
Join Date: Sep 2006
Location: Detroit, MI,USA
Posts: 810
Thanked: 289 Times
Default

Quote:
Originally Posted by lambdaplus View Post

@Jomz, EGR doesn't improve engine performance from the torque and power perspective, especially in Diesel! Also, EGR comes into picture at higher temperatures for reducing NOx emissions in Diesels.

I believe the EGR is turned off while engine is cold and just starting - EGR is turned on when the engine is warmed up. If the EGR valve gives more EGR than required - you engine might feel sluggish,

Just an opinion- I might be wrong.
Jomz is offline   Reply With Quote
Old 14th September 2010, 10:59   #23
BHPian
 
teknophobia's Avatar
 
Join Date: Mar 2008
Location: Ahmedabad
Posts: 319
Thanked: 22 Times
Default

I believe we had discussed this in another thread, but once again, everyone I know with a turbodiesel agrees that it feels a lot better when the outside temp is cooler.
Example, when I was in Mumbai I used to drive about 100 kms everyday from Navi mumbai to nariman point. I could notice a substantial change in the car's response/engine note once I crossed into mumbai/vice versa.
teknophobia is offline   Reply With Quote
Old 14th September 2010, 13:34   #24
Newbie
 
Join Date: Aug 2010
Location: Delhi
Posts: 22
Thanked: Once
Default

Any way to have the same performance when the engine turns warm/hot??
fink_ployd is offline   Reply With Quote
Old 14th September 2010, 14:07   #25
Distinguished - BHPian
 
sgiitk's Avatar
 
Join Date: Dec 2007
Location: Kanpur
Posts: 7,162
Thanked: 3,757 Times
Default

I am wondering whether the engine needs a thorough decoke!
sgiitk is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Common Rail : Why is cold start tougher at higher altitudes tsk1979 Technical Stuff 144 9th August 2014 15:46
How many KMs after cold start the car will feel better sreenivass Technical Stuff 30 13th November 2009 12:14
is k&n replacement better or a cold intake better? redsfx Modifications & Accessories 1 31st May 2007 16:58
WHEN and WHY does one feel the need for more power ?? mclaren1885 Technical Stuff 38 7th August 2006 08:21


All times are GMT +5.5. The time now is 22:32.

Copyright 2000 - 2017, Team-BHP.com
Proudly powered by E2E Networks