Technical question about temperature...

[johntra]

i have brava 1.6 16v and for last year i have problem with mine car that is hesitating when its cold, and when its hot i can feel it is bit slugish...i have some threads of mine problem and some people knows mine problem, like Jug...
To cut the chase i changed and cleaned everything on mine car, like new fuel filter, put on the new NGK spark plugs,new air filter,new coil pack i cleaned the Idle valve, i cleaned the lamda probe, i even bought the used fuel pump...i also checked the ressistance of injectors and everthing is fine, i had blown head gasket but i sorted that out...but mine problem still remains..when the car is cold i feel the hesitation and it is slowly accelerating, when the car is hot it is bit slugish..when i am in third or fourth speed and i press the gas pedal to the floor nothing happens...the car is slowly accelerating..like something is choking her...i think that somethong is wrong with air and fuel mixture...so i am thniking to clean the trottle body...is that hard job to do...so i am hoping that could be it..one more important question that i never mentioned here is that i think mine temp sensor is wrong...lets presume that on temp gauge on dashboard half is 90 celsius,which is logical because it is like that on other cars,mine fan cuts in on the other half of the meter, so i presume that is some 110 celsius...could this be mine problem of hesitation because the temp sensor is going wild, or somthing else...thanks

 

[jug]

dont bother cleaning your throttle body, that wont be the problem. a faulty temp sensor could be an issue. what rpm does the car idle at when cold and when hot? at what point on your temp gauge does the rpm drop to hot idle? (how many lines from the botton of gauge?) have you had a diagnostics check done?

 

[johntra]

when it is cold it idles on about 1100-1200 rpm,when its hot it idles normally on 850 rpm...i never watched when it drop on hot idle,but i think it is normal,,maybe one line or two,sometimes there is flat line..but i never watch that so i cant tell you with security..as i said earlier mine fan cuts in normally and i never had any issues with overheating...maybe it is faulty water pump, i never changed it when i bought the car, i am planing to change that with tensioners on spring...i really think that temp sensor is ok,how do you think that temp sensor can be an issue...and i went on diagnostics check when i bought it almost two years ago...i am thinking to go again..is it safe to go to some mechanics that have software for testing or i have to go to fiat garage on fiat/lancia tester...
i would like to give a go and clean the throttle body, is it hard or complicated to do it?i am really out of options...

 

[jug]

water pump cant be the problem, it cant cause hesitation, it ony pumps coolant. if there was a problem with it you'd notice overheating. people get paranoid about changing them but in practice they usually last as long as the car.

a fiat examiner machine is the best for a diagnostics check because it can access every module and get the most detailed error codes.

however using aftermarket diagnostic equipment is often very useful provided the correct software is used. if it is much cheaper i would try this option before going to fiat. however from experience there are many faults that dont get found using aftermarket equipment.

if you really want to try cleaning the throttle body just take the air intake pipe off the right hand side of it, then reomve it from the inlet manifold. you can clean it using petrol. i really doubt it will make any difference though.

 

[johntra]

i am telling you that because mine friend went to that shop with his golf MK4, and it found some things on it but with car is everything ok..that is not so serious but without that test he would never found out that..and certainly not to mention the money factor..it is so much cheaper...
when cleaning the throttle body what to clean?air intake pipe and the inlet manifold with the butterfly...is this the right term?
so we ruled out the temp sensor..i really dont think that could be the problem...it is acting normally...
as i told you before,i dont know do you remember,when i start the car and it works on idle a little,when i press the pedal and rev it on about 2000 rpm, the idle is starting to goes up and down..it falls down about 1800, than again to 2000..and all this is happening when mine foot is on pedal..sometimes when i press it lightly nothing happens,and it should goes up about 100 rpm at least...so that is mine problem,and all this is happenin when i am driving..but when its hot it is normal,but i can feel that car is sluggish...

 

[TheCROW]

Have you changed the lambda sensor? After that it's better to do a ECU reset also.
Just a thought

 

[jug]

there's nothing much to clean on the throttle body, you can wash the inside and clean the butterfly valve (as you sometimes have to if its not closing correctly causing idle problems) you could also try lubricating the butterfly valve with wd40 to make sure its moving smoothly, but generally its very rarely needed. the idle speed control valve is on the throttle body, but that only effects the idle, and your engine idles fine so its not that.

to be honest i'd have to see the car myself to get an idea, its hard to imagine what is happening.

a diagnostics check would be good to rule out any sensor issues

 

[johntra]

ive already cleaned the idle valve and i started the car without it, so i now know that is working...as i said i ruled out everything that is obvious on this engine..so i am thinking that the diagnostic check is what is only left...but i will clean the throttle body just to be sure,and to clean i it because i like to work around cars,especially around this one..one more question,could i start the car without inlet manifold when i clean the throttle body,just to see the difference?...anyway thanks guys!

 

[jug]

do not start the car without the TB or inlet manifold connected (why would you remove the manifold anyway?)

you can easily suck crap into the engine, although i doubt it would start as there will be nothing to control the air supply. if it did start with no TB or intake manifold it will rev as high as possible.

 

[johntra]

sorry wrong choice of words...what i meant is air intake pipe,not inlet manifold...i was watching today the throttle body..i am thinking or i am wrong that is hard job to do..i am scared to mess something, is there some sensor on it...i have fear of sensors..and what about the throttle cable,is it hard to remove it?
once i started the car and left it to idle fo 4 or 5 minutes because i didnt start it for 5 days,i noticed that car is running better untill it returned on normal idle of 850...that was happening around 1000 rpm,could i adjust the throttle cable to have some higher revs,maybe around 1000,or that is wrong?

 

[bridges]

Ok, first off I am not an expert on Fiats so I hope Jug or someone will correct any errors I make.

Why oh why are you not checking the CTS (Coolant temperature sensor) I think Jug mentioned this.

It tells the ECU what the temperature is and resets fuelling accordingly.
As put above i'm new to Fiats but on the older Renaults this sensor was the cause of your described symptoms.

Also have you checked the thermostat ? How long does the car take to warm up on a cold day?

Sensors do not always work or not work, they can still be working within operating margins but hence not work correctly. This is why a Fiat diagnostic would be needed as it should be more precise.

Also for good measure throw in some injector/fuel line cleaner into your fuel tank. Just because the injectors are pulsing does not mean they are not a little blocked.

 

[jug]

cleaning the TB is an easy job, but there's no point. trust me on this, it wont help.

you cant adjust the idle rpm using the accelerator cable unless you tighten it so much that the car is actually on part throttle and will never really idle, and that is not a good way to set up the TB at all. do not do it. if you tighten the cable that much you may snap it if you stamp on the accelerator pedal, and its not good preventing the car from idling, you'll waste fuel and cause it to get very hot in slow traffic, possibly causing it to overheat.

as said already, problems like this are almost always a sensor issue. i would get a diagnostic check done before trying anything else. if you really dont want to do that, then try changing the temp sensor as thats the most likely culprit.