Technical Fiat stilo 1.2 unresponsive throttle

[stilo97]

Hello guys I need your opinion. I have a Fiat Stilo 1.2 ‘03 5 door we bought it new back then. It is a family car very well maintained with no problems until last wear. Out of nowhere the throttle stopped responding and the car stalled. The mechanic said it was giving fault codes from the throttle body so I change it with a used one. For 5 months it was perfectly fine. Then it started having irregular idle I once again went to the shop they took my battery off for some time reconnected it and it was good again. Some months later I was washing the car I took off to return home and the car went in safe mode rpm stack to 900-1000 and no throttle response again. I went to another mechanic he also removed the battery for a while cleaned a ground point inside the engine bay and the car was fine again. Fast forward 9 months from this it stalled again out of nowhere because of unresponsive throttle and the solution was again to disconnect the battery for a while. I have spoken with some shops that specialise in Ecu’s and they told me that it is a known issue for the 1.6’s ecu but not for the 1.2’s ecu. I will have the wiring checked and I hope to find something. Any suggestions about what may be the cause? Or anyone with the same issue ?
Thanks in advance and sorry for the long text.

 

[stilo97]

I tested all the lines for continuity and they seem fine with average 0.03

 

[stilo97]

Can I inspect the ecu itself ? Is it difficult to tear it apart?

 

[koalar]

Can I inspect the ecu itself ? Is it difficult to tear it apart?

I don't know, let me see if can find out

I been and repaired a ECU on a mercedes, but have never been inside this one

The normal 1.4 ECU could be a DIY repair as long as you have the correct tools and skill level. as no parts are required

Some more info here

Bosch ME7.4.4 Repair - ECUs - ACTRONICS LTD

Bosch ME7.4.4 ECUs repair wanted? ACTRONICS remanufactures and repairs electronic car components.

www.actronics.co.uk

Be better to confirm before diving in, I take no joy with alfaodb

If you have a laptop with windows and Bluetooth you could try multiECUscan free demo and your elm327

 

[Zardo]

oh it's a stilo again

ECU repair

 

[stilo97]

oh it's a stilo again

ECU repair

I ve seen the video but sadly it’s not the same ecu

 

[Zardo]

There are videos for Bosch ECUs, too.



You could also just try and buy the same used ECU if you don't have a heat gun or if you've got poor soldering skills.

 

[koalar]

I have the reading from the 5v at positive I get 0.03 and ground 0.08. I tired to check with the obd scanner, I even got the pro version of the app I may have faulty scanner I will test with another one obd2

Mised this post

Are we saying there no 5v reference voltage on pin 3

Is that back probed with the connector still plugged in or on the pin itself with the connector off

 

[koalar]

Can I inspect the ecu itself ? Is it difficult to tear it apart?

Look like it's flooded with resin so not easy to do anything useful

 

[stilo97]

Mised this post

Are we saying there no 5v reference voltage on pin 3

Is that back probed with the connector still plugged in or on the pin itself with the connector off

i tested the wirring for continuity they all came back with avarege 0.03. Disconnected from the thottle and the ECU

 

[stilo97]

View attachment 479679

Look like it's flooded with resin so not easy to do anything useful

Wow why would anyone do that?

 

[koalar]

With ignition on do you have the 5v reference on pin three

Wow why would anyone do that?

I can't really see from the photo but guess there's some laser-trimmed resistors these need sealing from moisture

 

[stilo97]

With ignition on do you have the 5v reference on pin three


I can't really see from the photo but guess there's some laser-trimmed resistors these need sealing from moisture

i didnt try with ignition on i disconnected the battey. Is it safe to check with the battery on?

 

[koalar]

i didnt try with ignition on i disconnected the battey. Is it safe to check with the battery on?

I'd read the signal directly with a scanner

But if you can't get it to work you can measure directly

You have to be very careful not to short two pins together

But ithis is what I would do if I had to

 

[Mike1alike]

Is it safe to check with the battery on?

It's not safe, but... it is what it is!
Doing it carefully can make it safe.

 

[Zardo]

You'd need needle-type electric test probes

something like that

 

[stilo97]

How can i do it? disconnect the throttle body plug and probe 5V with ground? I already use the needles.

 

[koalar]

How can i do it? disconnect the throttle body plug and probe 5V with ground? I already use the needles.

Yes

Or you can back probe the connector (safer) which is what I normally do as I have loads of "T pins"

Or use a wire piercing probe (easiest) then seal the hole with some liquid tape, but not everyone has them

 

[Zardo]

Look like it's flooded with resin so not easy to do anything useful

apparently, one of several types of protective coating might be used.

How to remove them:

https://mgchemicals.com/knowledgebase/blog/how-to-remove-cured-epoxy/

https://www.sheenthermal.com/news2412161.html

but it's still a mess

 

[aschiuta]

There is 5 volts. If the 5 V voltage is missing you will have an error from the moment you turn on the ignition, just before starting the engine. When you turn on the ignition the throttle valve checks the calibration, it closes and opens and does low and high resistance values measurement of the potentiometers.

 

[koalar]

Well I totally messed up

While writing a reply in a cafe with people talking to me

Surprised nobody picked up on it

You need to disconnect from the throttle body and test pin 3 from here

With the ignition on


Sorry