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]

Hello!
The throttle body is flyby wired, correct?
Is it giving any fault codes now?
Besides the TB itself, you have the throttle pedal sensor that communicates with the TB. Is that ok? Does it report the correct position? Any fault codes on it?
Here is a video about an intermittent TB problem, that was caused by faulty electrical wire

The TB can be cleaned if you know what you are doing. You take it apart. It has some electrical contacts inside that get oxidized and that means trouble, you can clean them. And after you take down all the electrical components of the TB you can wash the rest of the TB with warm water plus detergent plus citric acid. The TB has the spring that keeps the flap closed and in time that gets dirty and after that it doesn't move easily anymore, needs more force to be applied to move and that is a problem for the little electrical TB device that moves the flap. So cleaning it can help a lot. Also, the flap itself or the TB opening get dirty in time. The flap is being kept open 5% (I think) on idle. If it's dirty it doesn't allow enough air to get in and that's the problem. So having it clean helps.

 

[Mike1alike]

Here is a guide about cleaning the throttle body

How to clean the potentiometer inside Throttle body

Hi Everybody. I would like to share my experience about the cleaning of the potentiometer inside of the Throttle body. I made this because I fight with bad idle after a big refurbishment and I thought I can try this as well. I had an other...

www.fiatforum.com

But you can do more than that, as I mentioned above. Take all electronic components out and give the rest a good wash.

 

[stilo97]

So far i have cleaned the ecu connections some grounding points with visible oxidation, my tb is clean in the intake side and the flap too but i dont know how to take it apart in order to take a look at the wiring. I ve seen the video i will inform the electrician to take a look at the ecu connectors for loose fit and take apart the tb for a deeper clean. As for the fault code nothing shows up now, only when it happens i get a faulty code for the tb.

 

[koalar]

What's the code P0???

For example on a generic code reader often gives a TPS = throttle position sensor error

But that can be a throttle body or throttle pedal

They often get mixed up

Without the code we are shooting blindfolded , and it impossible to help without taking wild guesses

A cheap code reader and a smartphone is under £10, a stand alone is around £15

Codes are manufacture and model specific

As an example P1220 on a panda is the throttle pedal, 9 times out of 10 a new pedal fixes it, but because the wiring is shared occasionally it's a using the same wires such as the Aircon linear sensor

But Google will send you in completely different direction

Without a code or code reader, and my blindfold still firmly on, after replacing the throttle body and still the same fault, erratic idle, safe mode, and intermittent,


Maybe unplug the throttle pedal and look at the connector

Sometimes a blast from compressed air can on the potentiometer sometimes fix them

 

[stilo97]

I have to wait until monday for the electrician i will keep you guys posted

 

[stilo97]

Hello again guys hope you all are doing well!! So the electrcian didnt bother to work with the car, he checked the wiring which was ok and then he just relearned the throttle body. He didnt check the throttle pedal neither the potentiometer inside the thottle body. So i will clean them myself and i will also get a obd scanner for the fault codes. I will post the error codes here and i hope that we can find something.

 

[stilo97]

Does anyone know the pin layout of the Bosch ME7.3H4?

 

[koalar]

Does anyone know the pin layout of the Bosch ME7.3H4?

What's the code

I can give you the pin out for particular functions, but I need to know what system I am looking for

ECU to which sensor

 

[stilo97]

What's the code

I can give you the pin out for particular functions, but I need to know what system I am looking for

ECU to which sensor

i need to locate the pins for the throttle body, i will run some continuity tests and also check the accelerator pedal I think this intermittent unresponsive throttle thing is a loose connection somewhere in the wiring.

 

[koalar]

There's no point in probing for continuity, it's working most of the time any rate

Start by plotting track a and track b in a scan tool

This can be done for the throttle body and pedal

It will tell you if power, ground, signal plus all the wiring is okay on all four potentiometersas seen by the ECU in less than a couple of minuites

It's been 4 week and we are no further forwards no code given and nothing to go on

 

[stilo97]

There's no point in probing for continuity, it's working most of the time any rate

Start by plotting track a and track b in a scan tool

This can be done for the throttle body and pedal

It will tell you if power, ground, signal plus all the wiring is okay on all four potentiometersas seen by the ECU in less than a couple of minuites

It's been 4 week and we are no further forwards no code given and nothing to go on

yeah i know i left the car in my hometown (350 km away ) in order to get it checked by an electrician but he didnt want to get involved and due to my work i couldnt make the trip to get it. I will have it this weekend, hope to have the obd reader too by then.

 

[Mike1alike]

i need to locate the pins for the throttle body, i will run some continuity tests and also check the accelerator pedal I think this intermittent unresponsive throttle thing is a loose connection somewhere in the wiring.

The continuity problem might be in the throttle body. There are little connectors inside that do get oxidized.

 

[stilo97]

I still wait for the obd reader... today i took off the accelarator pedal connector to give it a good clean with contact cleaner. I found out that the plug has a rubber seal and it s impossible to replug it with the seal on. Any advice? According to the estimated delivery i will have the obd tomorrow so i will post again.