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.

 

[Mike1alike]

Dry joint in Bosch ecu ? I thought only the Marelli does it and how is it possible to drive for months between?

It's not that! Just check the wires!

 

[koalar]

Dry joint in Bosch ecu ? I thought only the Marelli does it and how is it possible to drive for months between?

You got to start testing somewhere

It's bolted to an engine that goes through a lot of heat cycle's

There's a lot of threads with the P1688 not just on here and 1.2 without any resolution, they spent hours going through the battery, alternator and connector route

You have a way to test, it's only going to take less than 5 minutes and it will check the wiring grounds for the throttle body at the same time

If the test eliminates the ECU or it's connector at least it's a move forwards

 

[koalar]

It's not that! Just check the wires!

Why the aggression

 

[Mike1alike]

It's no agression. You just jump to extreme diagnose like damaged ECU before there has been ckecks made to simple things, like cables. Plus cables are prone do damage whilst ECU damage is very rare for this problem.

 

[stilo97]

You got to start testing somewhere

It's bolted to an engine that goes through a lot of heat cycle's

There's a lot of threads with the P1688 not just on here and 1.2 without any resolution, they spent hours going through the battery, alternator and connector route

You have a way to test, it's only going to take less than 5 minutes and it will check the wiring grounds for the throttle body at the same time

If the test eliminates the ECU or it's connector at least it's a move forwards

You mean to check it with the obd? I don’t have an option for the throttle body voltage in the app

 

[koalar]

You mean to check it with the obd? I don’t have an option for the throttle body voltage in the app

Just plot the signal track 1 an 2,

For there to be a valid signal their power and grounds must be present, The signal is a midpoint between the two

If you can rev the engine, they should move in harmony with no spikes, post a screenshot of you can

Watch the screen as you wiggle the connectors, but don't go to roughly, try anywhere you feel likely

There's an earth wire bolted to the ECU heatsink, the throttle connector, tap on the fuse box and so on

I am trying to avoid it from going the way of most of the P1688

Search results for query: P1688

www.fiatforum.com

Mostly with no resolution

The only resolutions I can find has been the ECU and that includes a single 1.2

The only other fix I can see is for if you switch the ignition on and then don't start the engine for a few minutes you get a P1688 and that was fixed with a software upgrade, I don't know whether it effects your vehicle or not but I doubt this is your problem

 

[stilo97]

Just plot the signal track 1 an 2,

For there to be a valid signal their power and grounds must be present, The signal is a midpoint between the two

If you can rev the engine, they should move in harmony with no spikes, post a screenshot of you can

Watch the screen as you wiggle the connectors, but don't go to roughly, try anywhere you feel likely

There's an earth wire bolted to the ECU heatsink, the throttle connector, tap on the fuse box and so on

I am trying to avoid it from going the way of most of the P1688

Search results for query: P1688

www.fiatforum.com

Mostly with no resolution

The only resolutions I can find has been the ECU and that includes a single 1.2

The only other fix I can see is for if you switch the ignition on and then don't start the engine for a few minutes you get a P1688 and that was fixed with a software upgrade, I don't know whether it effects your vehicle or not but I doubt this is your problem

What do you mean plot signal track ?

 

[koalar]

What do you mean plot signal track ?

Plot
Graph
Live data

However it translates best

Your should be fairly flat lines at idle


Make sure to do throttle not throttle pedal

You can check pedal separately but the free version only allowes two traces at a time
Post a quick result

 

[stilo97]

I don’t have the option for the throttle

 

[koalar]

I don’t have the option for the throttle

Shame

Try http://play.google.com/store/apps/details?id=com.AlfaOBD.AlfaOBDDemo

 

[koalar]

Did you setup your car in the settings
There's loads of fiats but the stilo isn't listed unfortunately


Some of the fiat 1.2 do it

View attachment 479588


Anyhow might be a backup plan if alfaobd fails also

 

[stilo97]

Did you setup your car in the settings
There's loads of fiats but the stilo isn't listed unfortunately


Some of the fiat 1.2 do it

View attachment 479588


Anyhow might be a backup plan if alfaobd fails also

I use obd2 protocol which supports Stilo

 

[koalar]

I use obd2 protocol which supports Stilo

Pick fiat and basic in the connection profile

It's there


But I don't have a stilo to see if it works

 

[koalar]

Any joy with either software

Kind of interesting to see some data

 

[aschiuta]

All error from p1681 to 1689 are related to the throttle valve unit. So disconnect the 12 v battery, disconnect the throttle valve conector and ECU connector nr. 1. Measure the 8 wires from ECU connector to throttle connector using multimeter set on OHM scale. Use cleanning spray for electronic components on ECU connector, throttle connector and wires connectors. Do not use wd40. Put them all in place and make test. If error is still there remove throttle body unit, open it and look inside to be clean. You can use same cleanning spray inside the throttle body components. Make some photos of inside. Again test after you put back the throttle. Still error then is time for purchase another throttle unit from ebay or local used car parts sellers. Search using part code from your throttle.

 

[stilo97]

All error from p1681 to 1689 are related to the throttle valve unit. So disconnect the 12 v battery, disconnect the throttle valve conector and ECU connector nr. 1. Measure the 8 wires from ECU connector to throttle connector using multimeter set on OHM scale. Use cleanning spray for electronic components on ECU connector, throttle connector and wires connectors. Do not use wd40. Put them all in place and make test. If error is still there remove throttle body unit, open it and look inside to be clean. You can use same cleanning spray inside the throttle body components. Make some photos of inside. Again test after you put back the throttle. Still error then is time for purchase another throttle unit from ebay or local used car parts sellers. Search using part code from your throttle.

I will test them first thing in the morning. I have taken apart its factory throttle body (which was changed form a mechanic the first time it had the irresponsible throttle) it is perfect clean, contacts and the potentiometer look very good also the gearing is good.

 

[koalar]

Any joy with the scanner yet

 

[stilo97]

Any joy with the scanner yet

I just came back from work tommorow I will have time to check everything we said, I will post updates in the morning

 

[koalar]

I just came back from work tommorow I will have time to check everything we said, I will post updates in the morning

Cheers once we can see the live signal it will make it easier

Just knowing if it's track a or b Halfs the work

Being intermittent If you meter it out and it okay it could just be because it was okay at that particular moment in time

 

[stilo97]

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