Technical Fiat stilo 1.4 95hp engine weird sound

[pantelismk]

Hi everyone... my fiat stilo is doing an weird noise when i aply throttle at around 1.5 - 2.8 rpms .... at any speed and gear.... the thing is that when the car is cold id doesnt sound at alla its like every other car... when the engine comes at its normal cruising temps its starts an weird knocking or maybe tractor-ish sound .... id doesnt do that while idle or while i have my foot off the throttle... its ony doing that when i aply little throttle..... at the beginning its was not noticeable but now it is and it doesnt sound good to me..... it isnt the pushrod(dont know if i spelled it correctly) problem as had it checked from underneath the car in carter....if anyone can help me with this .... i can contact with you provide some videos and sounds of the car if you think you can help..... thank you for your time

 

[Ralf S.]

Can you reproduce the noise when the car is stationary, or only when it's moving?

If it happens all the time, even when the car is standing still;

Have a look under the cam-belt cover and make sure that your cam-belt tensioner is still holding the belt tight and that the belt is central on the pulleys (not running off the pulleys). Grab hold of the water pump pulley and give it a good pull up and down to see if there is any play in the pump bearings.

While you're there, have a look at the flywheel pulley to see what condition the rubber insert is in. The pulley has a rubber ring bonding the pulley part to the central/crankshaft part (like a sandwich) and the rubber can deteriorate.

Check the exhaust heat shield to make sure it's not that, banging on something.

If the knocking isn't a metal-to-metal knocking... just more like a fast tapping sound, then check your spark-plugs are not loose and that the coils are in good condition. These would cause a misfire or hesitation and you don't mention that symptom.. but it's worth mentioning.

Do you have any octane booster? It could be your petrol is just rubbish/full of water and so the car is pre-detonating. Get some more octane in the tank... fill the tank with some new petrol from a different garage or stick a whole bottle of octane booster in there. Your garage might have sold you parafin or something.

If it only happens when the car is moving:

Does the knocking sound like something going round and round (knocking gets faster when the car is travelling more quickly) or does it knock at the same frequency?

Check the condition of the driveshafts. Jack the whole front end up (put each side on stands) and pull the driveshafts in and out of the cups. If there is more than a few millimeters of movement, then it may be wear in the inner CVs. Does the car "rumble" when you go up hills or when the road dips (so the suspension is compressed)?

It could also be the clutch. How many miles has the clutch done? Does the clutch judder or can you feel the knocking as a vibration under the clutch pedal, or is it just a noise?


Ralf S.

 

[pantelismk]

Ralf thanks for your reply ... the sound is faster when i put my foot in throttle as i travel if i go down a hill with gear on and the car accelerate it doesnt do it..... i checked the belt it doesnt do it i havent checked the water pump or the exhaust but im pretty sure something on the engine does it... i run lpg too didnt mention it before..... i might have something loose caz i can hear something like plastic treable after a little bit ill try look at other stuff and reply but can i send you somehow a video of the car when i throttle??? Plus how cat it be something loose and the car doesnt do any noice when its cold started???

 

[pantelismk]

Can you reproduce the noise when the car is stationary, or only when it's moving?

If it happens all the time, even when the car is standing still;

Have a look under the cam-belt cover and make sure that your cam-belt tensioner is still holding the belt tight and that the belt is central on the pulleys (not running off the pulleys). Grab hold of the water pump pulley and give it a good pull up and down to see if there is any play in the pump bearings.

While you're there, have a look at the flywheel pulley to see what condition the rubber insert is in. The pulley has a rubber ring bonding the pulley part to the central/crankshaft part (like a sandwich) and the rubber can deteriorate.

Check the exhaust heat shield to make sure it's not that, banging on something.

If the knocking isn't a metal-to-metal knocking... just more like a fast tapping sound, then check your spark-plugs are not loose and that the coils are in good condition. These would cause a misfire or hesitation and you don't mention that symptom.. but it's worth mentioning.

Do you have any octane booster? It could be your petrol is just rubbish/full of water and so the car is pre-detonating. Get some more octane in the tank... fill the tank with some new petrol from a different garage or stick a whole bottle of octane booster in there. Your garage might have sold you parafin or something.

If it only happens when the car is moving:

Does the knocking sound like something going round and round (knocking gets faster when the car is travelling more quickly) or does it knock at the same frequency?

Check the condition of the driveshafts. Jack the whole front end up (put each side on stands) and pull the driveshafts in and out of the cups. If there is more than a few millimeters of movement, then it may be wear in the inner CVs. Does the car "rumble" when you go up hills or when the road dips (so the suspension is compressed)?

It could also be the clutch. How many miles has the clutch done? Does the clutch judder or can you feel the knocking as a vibration under the clutch pedal, or is it just a noise?


Ralf S.

Ralf didnt check anything yet but can you read the prev one??

 

[Ralf S.]

If the noise increases with the engine speed, rather than the road speed then it's not related to the wheels, suspension, driveshafts or transmission.

It could be engine (ignition) or ancillary related.. (water pump, alternator, air-con pump etc.)

You can test the alternator or air-con pump by removing the auxillary belt. The alternator light will come on and your battery will go flat, so don't go too far but try driving with the belt disconnected to see whether the noise disappears. If it does then the alternator or a/c pump bearings or clutches are making the noise.

Water pump you can only investigate fully by taking the cam-belt cover off and feeling the pump for play. You can also start the engine and see whether the water pump stays "straight" or seems to wobble about. If the cam-belt is "straight" on the pulleys and the water pump pulley isn't wobbling, then it's 80-90% okay.

That would only leave something in the ignition. You might have a lazy injector, or a coil or a spark plug might be breaking down and causing a misfire.

But you didn't write "misfire" anywhere... so my thought is that the sound is pinking / pre-detonation. Have a look at the plugs to see if they're white or look like they've been too hot (melted).

Does the sound happen on petrol or gas, or both? If it's just on gas.. then the fault must be in the LPG system (injector or LPG-ECU unit if it has one). If it's on both LPG and petrol, then the problem will be the coils/plugs or ECU.

It's worth making sure any plastics and shields are tight.. when the car accelerates, the frequency of the engine makes the parts vibrate. Exhaust or catalyser heat shields can become loose (the mounting breaks so it's held on at just one end) and then it can vibrate against the exhaust when the engine frequency changes.

Ralf S.

 

[sasacalko]

I apologize for the poor English.
I have exactly the same problem with the fiat 500l 1.4 95hp, 2013.
how did you solve your problem?
thank you very much in advance

ps. the engine was taken out and opened, they could not find the fault

 

[sasacalko]

this is how my car sounds