Please Help! need your advice

[Richard]

I had a fiat diagnostic performed the other day and there were 3 things that were flagged up.

Throttle potentiometer O.C or S.C to +Batt.V =intermittent
Pressure sensor S.C to Ground /O.C. =intermittent
Self adaptive parameters below bottom limit =intermittent

Fiat said it is more than likely that 1 of the things above is causing the other. I need to know which 1 would you change?

I have the following problem.
When cold my revs jump between 1500 and 2000rpm and the car is very "twitchy" on light throttle. When warm nothing is wrong. Its a yr2000 1.6.

Before you say clean the idle valve i cant because its connected to my throttle body, next to the potentiometer.

Thankyou

Richard

 

[Tom]

First of all I'd check the electrical connections to both the throttle pot and the pressure sensor, always possible they are slightly corroded.

If that doesn't help change both the throttle pot and the pressure sensor. Those two probs are causing the third.

The jumpy response will be the throttle pot.

The self adaptive parameter prob is caused by the sensors giving out of spec readings due to them being faulty.

 

[Anonymous]

Re: Re: Please Help! need your advice

Tom

May i ask how u know so much about, what the fault on the fiat bravo/a could be.

Martin

 

[Richard]

Re: Re: Re: Please Help! need your advice

thankyou for the reply tom.

if you think the twitchy driving and the rev speed is all down to the throtlle pot wouldnt it just be that?

What does the pressure sensor cause when it goes faulty then? Oh and i dont quite know where this is located, could you please describe where to look for it.

much appreciated

Richard

 

[Tom]

Re: Re: Re: Re: Please Help! need your advice

The pressure sensor is used to determine the airflow into the engine, if its faulty then the ECU will be getting wrong airflow readings.

Check the connections first as the throttle pot comes as part of the throttle assembly (lots of ££) and the pressure sensor is still about 100 notes.

 

[Tom]

Re: Re: Re: Please Help! need your advice

Too much playing with cars, general dislike of garages so I do all my own maintenance and a 1st for my 3rd year thesis on fuel injection and engine management systems.

 

[Tom]

Re: Re: Re: Re: Please Help! need your advice

Oh and standing over the Fiat guys when ever my car has an injection problem and asking 'whats that mean?' and 'how do you do this?'.

One of the mechanics has a 1.6 and was very pleased when I told him where to get cheap injectors.

 

[Richard]

Re: Re: Re: Re: Re: Please Help! need your advice

im not to bothered about the cost as its getting done under warrenty from the garage where i bought it.

Im going to tell them that the the throttle pot is the culprit because all the connections are fine to the idle valve and potentiometer, and at lease the twitchy driving and erractic revs will be solved.

If the ecu is getting weired readings from the pressure sensor what will that cause? will it cause any of the above problems.

richard

 

[Tom]

Re: Re: Re: Re: Re: Re: Please Help! need your advice

That would also cause the above problems. If it thinks its getting more/less air than it is then it will either over/under fuel leading to all manor of problems.

If its under warrantee then get both fixed, the ECU says they are faulty so there should be no arguement.