Technical Stilo 1.6 ECU Mystery..

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Technical Stilo 1.6 ECU Mystery..

SypheRrr

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Jan 13, 2012
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Hi,

I have cutting out issue on 1.6 2002 3d Stilo. It happens during idle and on the move even when it is on gear. It cuts out during driving, no response for 2 seconds from the car and then starts working without me restarting with the key. Sometimes it needs restarting with the key.

It does the issue:
- On petrol and on LPG
- Cold and Warm engine
- Raining and sunny weather
There is no pattern in my opinion.

Errors on the dashboard:
- Combination of: ASR Failure, Alternator Failure, Loose Connection
or
- combination of: Engine Failure, Loose connection
- once it was Security failure
in general random errors.

I started with all the topics with loose connection in the forum i could find as well as guides:
-Cleaned the D4 connector
-Changed the crankshaft sensor
-Changed the coils
-Measured the accumulator - 12.6V with car not running; 14.4V with running engine
-started to go through the earth points- the only one left is the engine one i couldn't reach today because the point below caught my attention:

The ECU connectors the "A connector" referring to the guide: https://www.fiatforum.com/stilo-guides/338370-1-6-ecu-pinouts.html#content_start
the insulation seemed a bit worn out.
So i started checking the loom and dissembling the connector when I saw that there is something strange ( check the first attachment). In my opinion the previous owner has done some modifications in the connectors.

1) Blue wire connects to Blue with black i guess there is a resistance in the black joint and then goes in pin 13 of the A connector.

2) White wire connects to Black with yellowish wire again i guess through resistance and goes in pin 7 of the A connector.

Is there something like this in someone else's 1.6 Stilo?
How come something could be connected to pin 13, where the guide says it is not connected to anything :confused:
I counted twice the positioning of the pins from both directions so i am almost sure it is the correct pin number.
Could this be the reason for cutting out after i have driven the car for 2 years now ?
Initially it had troubles starting but they disappeared by themselves and it was OK for 2 years.

I am totally confused how to proceed.:bang:
 

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Sounds like it's the ECU itself. They get hot and over the years the pins move in the soldered joints.
Here's mine when I took mine to pieces.


 
Thanks for the post! :)
Did you have an issue and if yes, this solved it ?
It seems like it is hard to notice that looking on the top of the connector, right ?
Is this enough to cause bad connection ?

Also when dissembling, did you notice if you have such connections as the ones on the pictures ?

I will definitely check the ECU. Thanks!
 
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SGThirkell,
You are my hero!
Check out my pins... i bet this is the issue. I will fix it an come back with a post.
 

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Thanks for the post! :)
Did you have an issue and if yes, this solved it ?
It seems like it is hard to notice that looking on the top of the connector, right ?
Is this enough to cause bad connection ?

Also when dissembling, did you notice if you have such connections as the ones on the pictures ?

I will definitely check the ECU. Thanks!

Loads of errors and cutting out were my issues too, yes. I couldn't even tell the pins had moved from the outside till I took it to pieces and looked from the inside.
Your pics look like it's been really hot, worse than mine :(
I soldered mine but it still wasn't quite right and got random errors although very rarely after that to be fair. I came to the conclusion that the heat had done more damage than just the soldered joints and decided to buy a new unit for peace of mind. Not cheap but now never ever gives any errors and runs like a dream :)
 
Well I have fixed it. I will see how it behaves and If it is Ok I will leave it like this.
Thanks for the help!
I will post feedback in case someone else has this issue.
 
The pins affected were:

B-connector (referring to the guide):
54 Not connected
55 Not connected
56 Not connected
57 DBW motor positive (motorized throttle)

Further thinking if pin 57 is loosing connection for a moment it is normal the car to cut out as it can not control the motorized throttle --> no air.:)

P.S I don't know how i didn't notice it as it is obvious from this pic.
 

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So... Two days since the fix and not a single cut out :) You can't imagine the grin on my face :-D
Thanks for the help!
 
So... Two days since the fix and not a single cut out :) You can't imagine the grin on my face :-D
Thanks for the help!


When you put the cover back on is it not worth putting a strip of rubber on the inside to prevent the pins moving? OK not much can be done about the heat but if sitting in place the solder may still be making contact if pins are not moving about with the car vibrations.


Another thought. How about strapping one of those double fans you get for computer hard disks to it? They are also 12v and may keep it cooler.
 
Well I soldered them good enough. I suppose that if they didn't fall for 13 years they will hold for another 4-5 years.
Also yes, it is hot on the engine but in my opinion it is not hot enough to unsolder the pins in normal working conditions. ( if i remember well the soldering temperature is around 300-350 o C and I think the engine on top cant be that hot.Correct me if wrong. )
I suppose this is a result of engine overheating or something like this.

Thanks for the suggestion though, if something occurs again i will think of a solution maybe to move the computer body as well.
 
So,
1 week passed by and not a single error or cut out.
I consider my car as definitely fixed.

Thanks everyone for the help:)
 
Hi,
I want to share some update on the topic with the ECU and the pins in case someone else encounters similar problem.
I drove the car till beginning of October when unfortunately i broke my leg. The car was not driven until 17th ot November when i tried but the battery was dead. A friend of mine helped giving some power from his car and the car started. Unfortunately after I drove a couple of kilometers the car started again to cut off and display the errors on the dash.

Initially i thought the battery was the issue. Logically, before the broken leg it was OK, then the battery died and now there is an issue. So i got my battery checked if it is healthy in a local service and they said that it only needed recharging. So it was recharged but the problem was not solved.

The next thing I thought - OK I will check the ECU. It was interesting that when i opened there were several new pins slightly popped. The only from the 3, only 1 was connected following the ECU diagram in the guide. Furious on myself that i didn't change the ECU location, I thought it was a good idea to check and resolder all the pins. I went in a local PC service where they have all kind of equipment for such tasks and they resoldered all pins. They also saw on the electronic microscope that there were several other not that good pins which couldn't be seen with eye only.

Now after the resoldering all pins on the 2 connectors I changed the ECU location and now for today I drove 15km and not a single cut off.
I will check what will happen next several days and update the post in order to be helpful for other people.
 
i am currently having probems occasionally while driving around 3-4000 rpm and pressing lighlty on the gass and the engine jolts like its being cut off for a split second giving gas then again chocking for a split second. Then sometimes on idle the revs go up and down very slightly every couple seconds. Did you have something similar to this? i hope its not the ecu i changed it with a new one 2 years ago.
 
i am currently having probems occasionally while driving around 3-4000 rpm and pressing lighlty on the gass and the engine jolts like its being cut off for a split second giving gas then again chocking for a split second. Then sometimes on idle the revs go up and down very slightly every couple seconds. Did you have something similar to this? i hope its not the ecu i changed it with a new one 2 years ago.

No, there were no such symptoms in my car. It runs and idles perfectly just occasionally cuts off.
 
Well... after the resoldering i drove 150km without an issue when suddenly the car stalled again. It happened 3 times during idle.
To be honest I think that the problem is occurring much rarely than before, but it is still there.
I found a guy here who is fixing ECUs and he will fix mine as well. He said that most of the cases on these 1.6 Stilos there are some bad solders but in 8 out of 10 cases there is one chip which is overheating and is being damaged as well. When this happens random errors and strange behavior appears as in my case. Here in BG this will cost me 150 euros and the guy gives 6 months warranty.
I will come with some feedback after the fix how the things are going.
Fingers crossed.
 
OK so the guy gave me the ECU back on 1st December and till now not a single cut off for around 300km. Seems like it is fixed. I hope it stays this way as i said that it is fixed already 4-5 times in this thread. :D
 
Hello!

Been reading a couple of posts here regarding the ecu problems on the stilo.

in my case ive got a 2003 fiat stilo 1.8 16v my issue with it is that the electronic power steering is not engaging.

the PES motor was checked and rebuilt.

but once its connected to the ecu in the car is not recognized. i did erase the codes on the hitachi ecu thru MES and Vag Com 409.1 cable.

but when i try to access PES module thru MES says no response from ECU do want to clarify that the VAG COM cable was modded and i do have PIN 9 conected to the K line pin

im able to connect to the Airbag Module i did erase codes present there.

so currently no codes on ecu but no PES working.


after reading problems related to cracked solders i did attempt to open the ECU but seems this one is Disposable?

completely Sealed unit?

any suggestions?
 
Hi,
SypheRrr

Im new to the fiat forum just joined up and seeing if I can be of use to anyone.
I had a problem with my ECU overheating a few months ago. Random error messages were occuring particulary when the engine had been on for a while.
Were the ECU is factory mounted is a stupid place, right next to the heat of the engine and Iv heard of the heat actually melting the solder causing the problems.I remounted my ECU next to the battery tray with some small bolts drilled into the side of it and a metal tray to support the ECU. I have never had any problems again since and It defiantly sorted the issue. Might be worth a shot to see if it helps any!
 
Hi all I have a problem I think its my ECU but not shore.

I tested my Heat sensor with a wire stupid i know but didn't have a tester and now the car doesn't want to rev and it gives me temperature sensor error the whole time. can it be the ECU? it starts and everything else works
 
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