Technical Stilo 1.4 engine problem!

[chuffyshunter]

Hi.

I have a 55 plate Stilo 1.4 with a problemo. I drove it around 90 miles today, got home, took the battery off the Stilo (not the first time) to move one of my other cars. Left a code saver on the car to stop spiking the ECU’s on re connection.

Went to start the car. Cranked and cranked. Eventually it started. No engine management light but the engine was running like a turd. And the throttle pedal isn’t doing anything.

There’s a video below of the car running. I’m not touching the throttle in the video. The revs jump up and down all over the place and it dies. I have tried 4 different methods I’ve found for throttle relearn. None of them have made a difference.

On my diagnostics (Delphi kit) the pedal is showing a percentage when pressed and there are no horrible spikes or unusual anomolies. And no fault codes

Any help is hugely appreciated! It’s my daily driver so I don’t have to use the Turbo cinq and the Discovery for driving around pointlessly!

Here’s the link for the video of it running.... youtu.be/AN-19IImap8

The video appears to have no sound but the Rev counter shows you the problem!!

Thanks in advance
Jack

 

[Ralf S.]

That looks like the throttle position sensor.

They tend to get bunged up with soot and carbon so the ECU gets confused about what's happening.

The sending unit has a half-moon rotary valve in it that rotates according to the inlet manifold pressure. It should move freely... but if/when it gets carbon build up on it, it can't rotate.

Take the valve off and give it a blast of contact cleaner and/or kerosene based solvent. Depending on the design you may be able to free up the valve with a small screwdriver.. but be careful, since it's easy to damage it.


Ralf S.

 

[chuffyshunter]

When you say the sending unit do you mean the throttle body itself?

Thanks
Jack

 

[Ralf S.]

No.. (although I don't know the 1.4 ... so maybe yes).

The sending unit will be a small black plastic assembly, usually attached to the top or the side of the throttle body, most often on the inlet manifold side of the TB.

It looks like it's number 7 in the attached image.

If you find yours, remove it and have a look inside it, you might see something that looks like a flap or rotary valve. Just clean anything that looks like it should move, so that it moves freely.

A new valve is £55-60 so be sure it's the valve before you buy a new one..

If you can get hold of a second-hand one, then a straight swap should either solve the problem or improve things enough so that you know that the valve is causing some (if not all) of the problem.


Ralf S.

 

[chuffyshunter]

Just had a look for the sensor. Nothing found, I think it’s inside the throttle body itself.

However, I disconnected the throttle body, started it up, it fired up. Ran perfectly. No fluctuating idle or missing. Still wouldn’t rev (obviously).and it was only idling at 750rpm

Would suggest to me it needs the throttle body relearn however no methods I’ve found have actually worked. Are there any Diagnostic kits that will program the TB electronically? What are they.

I’ve also compared the two potentiometer readings in my diagnostics and they’re slightly different with the pedal fully depressed, track one shows 4.37V and track two shows 2.19v.

 

[bertiebumblebee]

I think I would take a trip down the breakers and then you have one to compare and also a spare if you manage to fix the existing one. My local breakers has 3 Stilo's in. I seem to be the only person raving through them --- far too regularly.

 

[Ralf S.]

Looking at the diagram, the sensor (number 7) looks like it bolts to the throttle body (number 3).. the diagrams aren't always 100% accurate but in this case, the TB seems to have holes in that would line up with the sensor.

You must have found it if you "disconnected" the TB...? In the old days a TB was just a butterfly valve with the accelerator cable attached to it.... so anything electronic on it is likely to be the sensor. Go onto eBay and search for "Fiat Stilo 1.4 throttle position sensor" and most of the results will be of the correct part, so you can see what it looks like.

I don't necessarily agree that the sensor must be okay and just needs to be re-learnt. Disconnecting it means the ECU has no signal from it, so it will switch to a default map. When you connect the sensor, the ECU will receive probably wierd information... it could be it needs re-learning or it could be the valve is sticking/dirty as I described above... but in any case, disconnecting it proves the problem is the TB, whatever the cause.

When I had a dicky TPS I bought a cheapo Chinese one off eBay and fitted it. It didn't actually solve the problem which made me scratch my head a bit... but it did change how the engine idled and, since it was clean, I could see what was inside it and compared it with mine, which seemed to be full of oily carbon.

Once I cleaned my old (Bosch) one, I refitted it and it was perfect. The cheapo one did the job since it helped me fix the proble but was obviously not accirate enough so I put it in my spare parts box.

If you can track down a second-hand one and swap it with yours to see what it does, that might be the easiest way forward. You could end up with a brilliant working sensor... or, if it doesn't make any difference at least you'll know that re-learning might be the way to go. I don't know the TPS re-learn procedure for the 1.4 I'm afraid...



Ralf S.

 

[chuffyshunter]

Thanks for your reply

I'll have another look for the TPS sensor tonight. Last night I decided I'd try pulling the wiring off sensors to see which would affect the running. Much the same as I do at work with MAF sensor faults!

When I pulled the plug off the TB it idled at 750rpm as i said.

Now I think about it, my TPS could well be the proble. It just seems odd that disconnecting the battery and reconnecting it has made it go from a perfectly good car to a car that won't run or rev up.

Anyway! I'll check the TPS sensor this evening and let you know my findings. There's nothing worse than a thread that never gets fixed!

 

[chuffyshunter]

Right. I’ve checked everywhere for a TPS in the engine bay and there isn’t one external to the TB.

Had the car running for about 3/4s of an hour to see if it was trying to learn and would sort itself out but it’s made no difference. However I have got a better video of the problem(i hope).

[ame]https://youtu.be/-7oFyA4380k[/ame]

Jack

 

[Ralf S.]

It still looks like the TPS.

I've found some photos of a 1.4 TB on the internet but none of the photos show where the TPS goes, so you might be right that the TPS is not attached to the TB itself.

But it has to be in there somewhere, so you'll need to find it. If there is any electrical wiring leading to the TB or the inlet piping any side of it, with a rounded-rectangular plug on the end that will probably be it.

>>> Have you had a look on eBay for a Fiat Stilo 1.4 Throttle Position Sensor? You'll see photos of what the TPS looks like, to help you find it. It's about the size/shape shown in the ePER image (number 7) above.

The TB photos I have show a large plastic cover clipped onto one side of the TB (I'd guess it would be fitted facing the bulkhead). Is the TPS under that?



Ralf S.

 

[chuffyshunter]

Anyone who ever experiences the same problem the fix is simple.

Fuse labelled as Engine coolant blower motor and nothing else in every bit of literature about the car. Apart from Multi ecu diagnostic software! Which states “engine coolant blower motor (1.8/2.4/JTD), engine management (1.2/1.4/1.6).”

I tested all the fuses in the engine bay box with a multimeter when the problem first occurred.. The Multi ecu software was stating the throttle learn was complete already and was still throwing the Main Relay fault. So I double checked the fuses this evening. Got to the fuse stated above (I’ll post which fuse it is as you look at the box tomorrow) and it tested out fine 0.0 ohms. Gave it all a good wiggle and tested the line it was in again, open circuit. Wiggles it again, 0.0 ohms. Pulled the fuse out, it all looked fine, however after checking the resistance across it 10 times, 3 of the 10 times it showed open circuit. First time I checked the fuses must have been one of the times it showed no resistance!! Anyway swapped that 10amp for one from the high beam circuits. Fired it up. Straight to normal idle, revved up no problem. Cleared the main relay fault and it hasn’t returned!

So! The problem was a fuse that had a hair line crack somewhere in it. Like I say I’ll post which fuse it actually is when it’s not dark and raining. Not the first time I’ve had this problem! Had the same issue at work on an Insignia throwing an ABS light.

Thanks for everyone’s suggestions and Ralf S for your input.! Like I said before, hate seeing unfinished threads everywhere.

Cheers
Jack

 

[Ralf S.]

At least it explains why the problem only started after you changed the battery. That was at the back of my mind but I didn't know there's a fuse for the "engine management"..


Ralf S.