Hello everyone!

After digging out the forum as a non-member I couldn't really find the exact same issue I'm encountering with my Fiat Stilo 1.6, therefore I thought it was time to ask for help.
Here it goes..

A week or two ago I went out with my car and a friend to pick something up. As he went away I waited in the car while I let it run idle. After a minute or so I heard the famous beeps, followed by the ABS, loose connection and what not. Since it was the first time I've experienced this, I turned off the ignition and tried to start again. Which wasn't a problem. Didn't have any faults or what so ever.

A week later I was driving to work when "high coolant temperature" showed up, car held in on throttle, so I was forced to stop from going about 80 km/ph. After turning the ignition everything was alright.
On my way home I got the same fault, again the car did a hick-up, but I could still drive my way home.

1. Immediately went to a friend of my dad, who owns a one-man-garage where he is almost retiring from. Connected the OBD which didn't really gave an error except for a U1601 mobility-something. It did tell me there were faults in the temperature gage, but I thought that was just because it's reading went out.
We tested the car battery, which matched the values of the highest battery available, I believe it was 14,4 idle with 490Amps starting power.

2. Since then I've checked the groundings, disconnected every piece of electronics I've built in (amp, camera, lcd-monitor). I also changed out the LED's I'd placed in the headlights, as I thought they might've messed with the CAN-bus. I've checked the ECU in the engine compartment cause of the possible overheating problems, and replaced it with a bracket next to the car battery. Nothing seemed off.

3. The day after I was driving to work when something different happened. The speedometer dropped to zero, engine light on, car loses throttle, and all in a second. After that second it seems nothing has happened, no faults on display, nothing. I decided to take another car to work, as I really can't be stalled in the middle of the road, as my journey to work contains a few tunnels.

4. Today I decided to check some other connectors, especially the D4. Again nothing seemed off. I went for a drive, after about 10 minutes the speedometer dropped to zero, same thing as before (3). Which happened twice during that 25 minute test-run. Back home I've let the car run stationary, nothing happned. As soon as I opened the door the engine stalled, don't know if it were a coincidence.
Checked the wiring loom that goes to the drivers-door, nothing seemed wrong.

5. This evening I decided to go on another test-drive. Again after a few miles speedo dropped and throttle 'dipped' for a second (3 and 4).
A few miles further I got the 'high coolant temperature' fault, 'stop engine'.

The reason I started a thread was the fact nobody seems to have the exact same problem, where the speedometer drops for a second, along side with throttle 'hick-up'. I was wondering if there's a hero out there who can give me a few tips, along side with a bucket of hope.

Thanks in advance.
~A desperate Fiat Stilo lover.

hello and welcome!


well, I cant help too much but I will start the ball rolling. Despite checking the D4, check it again, maybe even replace. what is the state of your battery? Does the ECU look ok, maybe you are developing an ECU fault..

Thanks for replying.

As I mentioned the battery appears to be in good shape, 14,4 volts stationary with about 450 Amps starting current.

The ECU looks fine, I've checked all the pins too see if some of them had fallen down into the ECU-casing. Which wasn't the case. There's nothing wrong with it's grounding either.

There didn't seem to be anything wrong with the D4 connector, I've checked the loom, the male pins and the female sockets on the connector. They were all in good shape, appart from a little dirt on the loom it looked brand new.

To make this problem even worse, I went to work this morning without any fault or other symptom.. It's a 40km drive, so I'll see if I can make it back home.

Back home.
The problem seems to be reduced to the "high coolant temperature, stop engine" fault.


Had two of them on my way home, the gauge spikes to max, warnings pop up, engine withdraws, and after a second or two the gage returns to the middle, as if nothing happened. The warnings stay a bit longer but goes away after about 10 seconds.

Now I know the sensor takes care of the coolant temperature is just a bi-metal thermostat that creates a resistance based on the temperature of the bi-metals. Cooler results in a high voltage, too hot results in a low voltage. So for some reason the voltage on that sensor drops, but only for a brief moment.

BUT, if it's really the sensor, could it cause the other problems mentioned, like ABS fault, ASR fault etc?

Does anyone know where I can find this coolant temperature sensor?

in my experience with the 1.6, multiple faults like this almost always point to D4 or ECU fault...

If it's an ECU-fault, then why am I only having trouble when I drive back in the afternoon?

Again this morning off to work, no troubles whatsoever.

The journey back gave me an dead engine, while being in the process of entering a roundabout. The dash showed a battery-light, and the oil-light. Don't think they have anything to do with a problem, as I believe those are also shown when you stall your car by letting the clutch come up to fast.

A few miles further the same issue, car stalled while I was slowing down for a traffic light. When I flipped the ignition I got the 'ASR-failure', and the car wouldn't start. Immediately flipped the ignition again, this time the car started without any problems.

I could continue the rest of the journey, when I was about halfway, without a single problem (45 km drive).

One this I did notice is that when I'm braking I can hear something click in the fusebox, probably a relay. This does not happen when I push the brake-pedal while standing still. I have never noticed this before, so is this normal? A pump that's getting switched?

I would say heat, simple. The ecu is bang next to the engine, if the solder is loose, then the heat will make that worse, whereas a cold engine/ecu/solder may contract enough to make a contact. that's why you get a seemingly random fault


I'm not saying it is, it just sounds like it.


Have you got ECUtalk and appropriate leads? I would hook a laptop up to it asap.


as for the brake light/relay, could be onto something there, so I would check the brake switch on the pedal, and the relays for the rear lights...

Thanks for the fast reply.

Well yeah I could be a factor, that's why I've replaced the ECU next to my battery. I think it's almost impossible for it too get hot enough now, in a way that it would (partially) melt a solder.
I've only hooked up OBD to check the error codes, I haven't monitored any live data if that's what you mean.

The switch could cause the problem, but if that's the case I would have to hear the clicking when I press the pedal, even when standing still, which isn't the case.


I've ordered the heaviest battery that fits my Stilo, it's a 58 amps cold start battery. Along side I have ordered the brake-switch, just to be sure. I will replace both of the tomorrow or saturday, where I will also clean up every connection on and around the battery, like the fuse-plate.



I will update as soon as they're placed and tested, in the meanwhile I'm all ears to suggestions.

good luck, its an intriguing issue you have, I'm very hopeful you can find the solution.

Update

Just finished a 30 minute drive in 32C heat(!), damn it's hot outside.

Before I started the test drive I'd replaced the battery. Took the old one out, cleaned every contact I could find. Inspected the fuse-box next to the battery, cleaned it as well. What I noticed was a very small strip of metal between fuse F16 and the gray housing, it was 'dangling' right between the two contacts. Not sure whether it could cause a short as the piece of metal was quite short.

On top of cleaning all the connections I also decided to bring an extra lead from C15 to the (-) of the battery.

I did not swap the brake-light-switch yet, as I want to know what caused this problem so it might help others in the future.

GUESS WHAT, HAVEN'T HAD A SINGLE FAULT DURING THE TESTDRIVE!
However I am not too cheerful yet, as it happened 1 out of 2 drives. At least I can rule out any fault caused by the outside temperature.
I will take her for a spin again later today, I'll post the outcome.

Update


No problems today whatsoever, only thing that happened was a stall right after starting the engine, but that has to do with cleaning the air inlet valve.

To sum things up, hoping it might help another, the things I've done to solve this problem:
- Changed the battery, not a higher capacity one.
- Cleaned up all terminals connected to the battery.
- Cleaned the fuse-box on the right-top side of the battery.
- Added an additional ground directly from the battery to 'earth-point' C15.
- Re-newed the Brake Light Switch.

Since it's only been a few days I'm not 100% sure my problem is solved, but it seems to be so. If anything comes up I'll update this post, if not, you can count it solved.

Hello members,
I got a problem with my Fiat Stilo 1,4( 2006)
It started by show( check the engine) on the computer and it started loosing power.
The mechanique put new spark plugs(4), it didn’t work
An other mechanic suggested that the chamber no 3 does not produce enough power!
What would you advise me to do?

Fidele said:

Hello members,
I got a problem with my Fiat Stilo 1,4( 2006)
It started by show( check the engine) on the computer and it started loosing power.
The mechanique put new spark plugs(4), it didn’t work
An other mechanic suggested that the chamber no 3 does not produce enough power!
What would you advise me to do?

Click to expand...

Is the compression on no.3 cylinder down? Do you have the cylinder pressure figures from all the cylinders (it's interesting to see what the difference between them is)?

Otherwise is the car smoking more than normal?

Is it overheating? Does the heater blow hot and is the radiator hot all the way to the top, when the car is completely warmed up (but don't put your fingers inside the fan casing to test it.. )


Ralf S.