faulty Ecu temp sender

[rocky 0]

Hi guys,

 

I have a tempreature related question too.

 

I will change my ECU temp sender on my Mi16 (BX16v) as an attempt to cure my overfuelling. The previous owner said the car has a cold temp sensor - what does this mean? and whats the difference to a standard temp sensor?

 

Can i just buy a new 'normal' temp sensor?

 

My fan cuts in on third bar, could this cause overfuelling too, or is this reasonable? i realise now that the fan speeds or when it cuts in doesn't effect fuelling, but I thought that if fan cuts in it will keep radiator cool, which cools the coolant when it passes thro and so the ECU temp sensor registers colder coolant and puts more fuel in - I am probably wrong with this.

 

PS: sorry for lots of questions, but this place is a haven for learning technical knowledge!

Edited July 2, 2007 by rocky

[welshpug 1,657]

I will change my ECU temp sender on my Mi16 (BX16v) as an attempt to cure my overfuelling.

 

Can i just buy a new 'normal' temp sensor?

 

My fan cuts in on third bar, could this cause overfuelling too, or is this reasonable?

 

i realise now that the fan speeds or when it cuts in doesn't effect fuelling, but I thought that if fan cuts in it will keep radiator cool, which cools the coolant when it passes thro and so the ECU temp sensor registers colder coolant and puts more fuel in - I am probably wrong with this.

 

 

1, good place to start, ish

 

2, yes

 

3, no.

 

4. no, if the fans keep the coolant cool the engine will be cool, It'll need a different amount of fuel.

 

[Simes 248 2 Cars]

Yes, ECU temp sensor tells the ECU it is 'winter' and basically leaves the 'choke' closed so you end up running rich even when warmed up.

Edited July 2, 2007 by Simes

[M_R_205 5 1 Cars]

as were on the subject ( all i seem to do lately is hijack threads sorry lol) would a dodgy ecu temp sensor cause poor starting, ie cranlks for a good 10+ secconds before starting?

 

sorry again

Paul

[Pugnut 9 1 Cars]

as were on the subject ( all i seem to do lately is hijack threads sorry lol) would a dodgy ecu temp sensor cause poor starting, ie cranlks for a good 10+ secconds before starting?

 

sorry again

Paul

thats possibly the non return valve in the fuel pump faulty. meaning the fuel depresurises in the rail and takes longer and longer to start the car.

i've had this twice now on two different cars . best way to check is to crack the fuel feed pipe on the end of the fuel rail before you go to start the car from cold . there should ALWAYS

be lots of pressure in there . even better to borrow a gauge and fit it in line .

[rocky 0]

1, good place to start, ish

 

2, yes

 

3, no.

 

4. no, if the fans keep the coolant cool the engine will be cool, It'll need a different amount of fuel.

 

 

Thanks WelshPug!

 

Just to be sure the answer to question 4 means that 'cool' coolant will not cause more fuel consumption?

[welshpug 1,657]

Thanks WelshPug!

 

Just to be sure the answer to question 4 means that 'cool' coolant will not cause more fuel consumption?

 

 

It will, as cold engines use more fuel, but it wont be the cause of the problem.

[Rob_the_Sparky 9]

thats possibly the non return valve in the fuel pump faulty. meaning the fuel depresurises in the rail and takes longer and longer to start the car.

i've had this twice now on two different cars . best way to check is to crack the fuel feed pipe on the end of the fuel rail before you go to start the car from cold . there should ALWAYS

be lots of pressure in there . even better to borrow a gauge and fit it in line .

 

No such thing as a perfect seal, it will eventually leak down. The difference I've noted is that on cars that start properly you sometimes hear the pump fire up for a second or so before you engage the starter. On my 309 that takes a few cranks to fire up this never happens. Therefore I think the issue lies in the tachy not priming the system rather than the non-return valve not doing its thing.

 

Rob

 

P.S. Oh and can we keep thread hijacks down please?