Please, help me save a stilo!

[Francesco6n]

Hi to all, im a new member (sorry for my bad english).

I have a fiat stilo 2003 1.6 16v with 173k km and i love it so much! But... i think she's dying.

Last week i was turning around with my car and, after a looong burnout is 1st gear, i hit the brake, put the 2nd gear in and then the car stalled.

I have started the engine again and everything was ok. After a few km the car started to misfire, the gas pedal was almost dead and the car stalled every 10seconds. I dont know how i did it but i came home at 20km/h and 2/3 cylinder misfiring.
The strange thing ? No errors in the ecu.

I've try to fix the problem but no luck, here the list of job done:

Throttle body clean + potentiomenter clean.
Ecu resolder (i have found the pin 56 desoldered, i dont remember if "a" or "b") and relocation.
New earth wires from negative to throttle body, ecu, engine and chassis.
Earth soldered together because the "earth box" (the one situated next to the battery) was broken.
New spark plugs (this is not the problem anyway)
Cleaned map sensor

After these jobs the car now starts BUT the idle is not good.
After 5 minutes it starts to oscillate from 1500rpm to 400rpm an then the engine stalls.
So, if i drive it, every traffig lights or every stops the engine stalls.
When i have no stops (like in the motorway) i have several misfiring and the car have no power, i can only drive it in city.
Fuel consuption is crazy, it smells unburned fuel, and.... NO ERRORS IN THE ECU!

Please, help me, i cant imagine that i must change my beautiful car after a burnout.

Thanks

 

[Abarth L]

Hi

ECU soldering, ouch hope you grounded everything and followed anti static procedure, maybe it is now broken that is why you don't receive as any ecu alarms, hopefully not.
My thinking is that your timing might have moved, timing belt slipped?
Although this should gave a few ecu warnings.
But worth a try to check the timing.
You can also try to check for a compression test on all 4 cylinders.

 

[Francesco6n]

Hi Abarth L, thanks for the reply

This week i'm gonna check the timing belt, the compression and the fuel pressure.
But i think is an electrical issue because sometimes, only 2 hours a week, i can drive normally, no misfire, no stalls and perfect idle.
I'm gonna also change the rpm sensor.

 

[varesecrazy]

Burnouts.. : vibration

When it runs well.. is it hot or cold?

The crank position sensor maybe.. they NEVER leave a code

 

[Francesco6n]

Hi varesecrazy, the issue is more visible when the car is warm, with the engine cold i can drive normally but it misfire.
With engine warm i have misfire and the engine stalls at every stop,
It is not always the same!
Sometimes i have the stalls even at cold engine, sometimes no misfires and sometimes i cant even drive the car because the engine stalls every 10 seconds.
I think my ecu work because if i disconnect the lambda sensor, the engine light come out!

I will try to change it

 

[cris1117]

crank sensor, easy job little cost.

 

[Francesco6n]

Hi cris1117,
You mean the one on the bottom pulley right ?
Because i think that my car have another sensor on the camshaft pulley.

 

[Schumi2001]

Burnouts.. : vibration

When it runs well.. is it hot or cold?

The crank position sensor maybe.. they NEVER leave a code

I beg to differ.

When it went on my Sei, I got the crank position sensor fail code from my OBDII reader.

 

[varesecrazy]

I beg to differ.

When it went on my Sei, I got the crank position sensor fail code from my OBDII reader.

I've never experienced it..

But with the old JTDs is was a relatively common issue.

Without its input.. there was nothing to tell the ECU it was rotating.

No rotation : no injection - ignition

I never owned a stilo.. they were not sold in my region

Sensor is cheap and easy to change .. worth a try.

 

[varesecrazy]

If it has a camshaft sensor too..

Then yes eithing giving bad signals should produce an MIL.

Might be worth unplugging. And cleaning connectors.. checking wiring.

See if it run ok with it disconnected
( 1 sensor at a time)

 

[Francesco6n]

I will try and then, i will do a diagnosis to know if the error is shown or not

 

[cris1117]

From memory (which isn't great these days) its just below the starter motor so you need the car on ramps or stands.

Looking from the top left side of engine you will see a single wire that runs down the back of engine follow that it will lead to the crank sensor.

I sold my Stilo a few years back with 300,000 miles on the clock and still going strong a very solid car.

 

[Francesco6n]

Hi cris1117 i'll try on monday evening!
For now i'm just thinking: if the crank sensor is gone, i must have an error in the ecu, like an incoherence of the data of the crank and the cam sensor!
The strange of my engine is that the car, very occasionally, runs very smooth, no problem at all for just 5km or so, and then starts to stall and misfiring.
Maybe i need to resolder the WHOLE ecu and not only the 128 pins.
Is possible that during the burnout with engine heat and vibration, the ecu was damaged somewhere ?
The ecu is strange because i can connect with the diagnosis like 1 time in about 30 minutes of trying, autocom continue to say "unable to connect" and then, sometimes it work!
I dont want to change my beautiful car.

 

[cris1117]

The crank sensor is a very common fault with the Stilo, I cant remember if it showed a fault code in the ecu or not.
I seem to remember the message “loose connection” being displayed on the dash but only once, I latter discovered this was a bad translation from Italian to English and should have read lost connection, I assume to the crank sensor.

The problems it caused where as follows.
Car sometimes drove fine and always ticked over and revved fine when not under load.

Sometimes when hot it would not start straight away and might have to be left to cool before driving.
When the problem did occur it would be almost undrivable kangaroo and cut out as soon as you stopped it would normally restart but not always, leave to cool down and would drive fine for a time then it would all repeat itself.

Eventually it cut out and would not restart, I fitted a new crank sensor in about 15 minutes it cost I think about £20 and all was fine afterwards.

 

[Ralf S.]

I'd go with the crank sensor before the ECU.

If it was the ECU then it would be much more likely to cause the same symptoms all the time. This problem sounds intermittent, which means it's more likely to be a failing crank sensor.

In any case, changing the sensor isn't a huge job compared to dismantling the ECU, so it's worth a try.

You won't always get an error from a crank sensor. If it can communicate with the ECU then the ECU thinks it's okay... but the sensor itself might not be detecting the position of TDC when the pulley (crank or camshaft - I don't know the 1.6) goes by, or it may detect the signal but is not always able to transmit it.


Ralf S.

 

[Francesco6n]

Hi Ralf S. I've ordered the crankshaft sensor and it's coming.

According to my schematics, the camshaft sensor has 3 wires: +12v, 0v and the signal.
So, i think that if the ecu see the signal from the crankshaft and not see the signal from the camshaft, its like that the timing belt is not mounted, so there should be an error.

The crankshaft sensor has 2 wires, the +12v and the feedback.
So if this sensor doesnt work but the ecu still reading a value from the camshaft sensor, it should give me an error.
I have read that if the crankshaft sensor is removed or broken, the car should pop out the "lost connection" error.
This evening i will try everything, from the timig belt to the disconnection of one of these sensor.

I will make you know.

 

[Francesco6n]

Ok, i've done few checks.

Fuel pressure is ok
Timing is ok
Cleaned connector d4
Found lambda 1 wires without insulant, fixed.

Disconnected camshaft sensor: the engine starts misfiring, irregular ilding and then it limps. Error p0340 stored.

Disconnected crankshaft sensor: the engine immediatly stops, lost connection warning on instrument panel. Error p0335 stored.

Disconnected map sensor: the engine starts to shake and, when i press the gas pedal, it stalls. Errors p0110 and p0105 stored.

Reconnect everything: the engine starts normal and runs normal. After 1 minute it starts shaking and then stalls: no errors stored.

Im starting to loose hopes.

 

[Ralf S.]

Fit the new crankshaft sensor and see what happens.

You might also need to replace the camshaft sensor, since the two of them work together and each one on its own can cause the same symptoms. I'd be fairly confident that it's one or the other.

Don't get hung up on fault codes. If there's a failing component, something is not working how the manufacturer designed it, so you might not get a nice "tidy" failure.

If new sensors don't solve the problem then it may be time to have another look at the ECU. Your issues only seem to happen when the engine has been running a bit.. so there's a good chance that it's caused by heat. Is the ECU on top of the engine still, or did you move it next to the battery?

If you took the ECU apart and re-assembled it before, and it still works then have another look at it... but because something only goes wrong when the engine has had some heat soak, I think it's more likely something "solid state" breaking down.

If the ECU is out of the way and being fed by cool air, then also take a look at the coils. I think the 1.6 has coils on top of the plugs (?) If so, take them out and examine them for any arcing (like a pencil line) or physical damage/melting around the spark plug connectors. If you have a spare good coil, it's not a tricky job to replace one coil at a time when the problem starts and see whether it makes any difference.

Usually an arcing coil gives an error code, since it's doing something unusual.. so I'm not convinced too much that you'll see anything on the outside... but if the coil is degraded internally it would still fail when hot and then maybe not give an error (so the ECU thinks everything is okay, so there's no code). It's maybe an idea to check next, if the new cam/crank sensors don't do it.


Ralf S.

 

[Francesco6n]

Hi Ralf S.

I have moved away the ecu from the top of the engine, now is located near the battery, far away from the heat.

I will change the crankshaft sensor and then, if i dont solve, i will change also the camshaft one.

I have tested the coils and i've found no problem, my doubt is, why my car started have problems after one burnout ? Is strange!

 

[Ralf S.]

I don't think it was the burnout itself that caused the problem but if the engine was hot and you were hooning about, putting a lot more electrical heat through whichever component is now failing, then that might have been the last bit of extra load or strain that broke it.

It's definitely unusual though... as if the car is having its revenge.


Ralf S.