Team-BHP - Strange Behavior of my ALTO, Expert's Advice needed

hello guys,
after reading my post you will find it a bit strange, but so do i !!

i observe that my alto behaves a bit strangely on the engine rev upfront.
on some fine day it moves pretty fast, accelerates very quickly with good torque in the 3rd gear and the engine is pretty rev friendly.

but again on the next day the engine becomes sluggish on the 3rd gear and takes some delay to accelerate. the engine doesnt rev quickly. it revs gradually.

the fuel in the tank is same, the tyre pressure same and the roads also the same. there is a replacement K&N airfilter fitted on my alto.

i dont understand what exactly changes that changes the behavior of my car. i believe the intake air temp changes daily but it shouldnt cause such an drastic difference?

Please can anyone throw a light on this? please:

Quote:

Originally Posted by theMAG (Post 1011198)

Clean the filter, intake manifold and replace spark plugs. I'm assuming your car goes through regular service intervals for other factors to be taken care of.

my car is very well maintained. filter is clean everything is ok. i have also put petronas fully synthetic syntium 3000 engine oil.

the problem is suppose i am driving today and the car is running damn fast with quick throttle response today, tomm it doesnt. it suddenly becomes sluggish.

again may be the 3rd or fourth day it may again zoom fast. i dont understand exactly what parameters change which causes this abrupt phenomenon.

it has nothing to do with the servicing of the car

Hi amit,

no machine performs the same way during all the time. Thats why F1 driver (basically any race drive) say, the car/bike was very good today blah! blah! blah! somtimes it works fine during qualifying but under performs during the race.

As as per what you said, i agree! the difference should not be this big and is usually negligent. But defenitely noticeable. As you said, there is cleary an underperformance factor here. Check this way....

test your vehicle in a/c off, same flat-straight road, same tyre pressure, same carrying load, same fuel, same time of day, because time will affect the outside temperature and so towards the engine performance. I suggest you test against evening-night times. If you still see the difference time to time... then there could be 2 problems:

1. inconsistency in the Air fuel mixture or combustion

check the carb; clean air-filter blocks, replace spark plugs and if problem still exists, i suggest you to replace the K&N to the factory fitted air filter and notice the inconsistency issues.

2. performance loss in the engine

sometimes when the engine-oil becomes heated up, it becomes thinner. when it becomes too thin, it normally stops doing its job of lubrication and there is some friction generated in the engine which will make your car underperform. This you will notice mostly during long drives only.

Also Amit, performance filters do help in getting more air into the combustion chamber (cylinder), but if your fuel flow is lean, then you have a lean mixture (more of air and less fuel) which will still underperform. But i understand that is not the problem here.

guys thanks a lot for helping me,

but again i am saying there is impact of...its not that i am driving with ac and then switch off..i know that surge due to ac.

also there is no problem with the injectors or cleaning or anything

if that was so how can the car running okay in the morning run slow in the eve and again run fast on the next day :Frustrati

Quote:

Originally Posted by gemithomas (Post 1011268)

Is it that it runs good in the mornings and becomes sluggish when heat increases.

it was just and example of the morning and eve i gave. u can also put it as today on 11th oct it is running pretty fast but on 12th oct it will run slow and again on 13th oct it will run fast.

this is just and example..but this pattern keeps on changing. its bugging me big time.

can someone give pointers on how to check what parameters are exactly changing? is it related to ECU ?:deadhorse

Quote:

Originally Posted by abhibh (Post 1011281)

Are you pulling it with AC on in both the cases ?

no the AC is off.

Quote:

Originally Posted by BaCkSeAtDrIVeR (Post 1011290)

Fuel quality? Do have a long, hard look at your fuel sation.

And are you sure that the fuel filters are replaced during service? (unscruplous service station?)

And have you tried something on the days when it is sluggish?

i need to check the fuel filter. i observe this with same fuel in my tank. even if i dont refill. that means suppose i fill 10 litres then with the same consumption of the 10 litres i find this problem .

do u mean to say that some clogged particles in the fuel filter cause this and then keep on moving so that sometimes i get good power and sometimes when they clog the holes i face the problem.

Quote:

do u mean to say that some clogged particles in the fuel filter cause this and then keep on moving so that sometimes i get good power and sometimes when they clog the holes i face the problem.

I am hinting in that direction.

Am not familiar with modern MPFI petrols - or petrols of any kind.

But old diesel heavy vehicles I know used to have this problem with bad fuel filters - particulary, the old gen diesls have a micro fuel filter mounted on the fuel pump. (of course, will vary with model and make.)

I think its perfectly normal,Amount of oxygen content in the enviornment,Outside temperature affect the overall functioning of the engine.
I feel the same in my zen too and used to feel it in my 800 too.It was never the same always.The throttle response the acceleration varied from one time to another.
For example the zen somtimes pulls effortlessly in 4rd gear from 40 with enough acceleration to please me and sometimes i have to downshift to 3rd.
Some people observe this minute acceleration difference and some people dont.
If there a pressure difference of 1 or 2 psi in any of my tyres i know for sure that air needs to be checked,The vehicles handles a tad different and thats super keen observation,so i guess thats the same with you.