156 2.5L V6 Throttle Problem - Alfa Romeo Forum
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156 2.5L V6 Throttle Problem

Hi, can anyone out there help?

Recently, after the car had been running perfectly, when I started the car outside my local supermarket it was running a bit lumpy and would not get above about 2000 revs.

Power seriously down and limped home between 20/30mph.

Diagnostic checks suggested a throttle problem.

Both the throttle sensor and the throttle body have been replaced ( second hand but known as working) but no difference.

The problem persists, and local garage are suggesting the ECU may be faulty.

Would be very grateful for any advice any of you may have to offer.
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Last edited by rxe; 30-08-13 at 11:43.
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Without access to diagnostics, my next thought would be the MAF. Poor idle, flat spots, hesitation, bad throttle response are all signs of a failing MAF.

Try disconnecting it - the ECU will go into a default map and probably be better. If so, then order a new one (sensor only, don't spend ££££ on a complete one) from someone like worldcarparts - get genuine Bosch, the part number is on many threads on here. You can try cleaning the existing one, again, the instructions are all on here.

Do you have specific error codes, and is the engine light on - that would shed more light on the problem?
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Could be dodgy connection in the potentiometer wiring...
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Which 2.5 V6 engine is this? Euro 2 or Euro 3?
156 equipped with eur2 engines has a big white connector behind the glovebox which is a weak one. In 156 v6 eur3 this connector has been fixed.
Concrete trouble codes would be useful, anyway.
With new TB, the TPS reset has been performed?
Before change anything, try to go to a place where they are able to perform a parallel diagnostic (check sensor signals and output signals real-time at ECU). With the help of reference data, they will be able to say which signals are incorrect.
At least signals of TB/TPS at the connector of TB and at connector of the ECU should be checked before change anything.
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156 , 25l , problem , throttle

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