Non runner. - Alfa Romeo Forum
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(Post Link) post #1 of 2 Old 27-07-11 Thread Starter
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Join Date: Jul 2011
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County: Derbyshire
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Non runner.

Hi guys,

I have a 2004 Alfa 156 2.0 JTS. It will just turn over and not fire, Sometimes it will start and run for 1 second then it will stop again.

It has three codes present in the engine ecu,

1 , Phase Sensor (No Signal)
2, Fuel Pressue Sensor (Past High Limit)
3, Brake Servo Vaccum Sensor.

The Phase sensor has been replaced and the fault persists. I have checked the inputs & outputs of the phase sensor with a scope and they all read flatlines.

I get 5v on pin 1 (Black) , 12v on pin 2 (Yellow/Green) and Earth on pin 3 (Orange).

From past experience on other makes of vehicles I would expect 12v on pin 1, 5v on pin 2 and earth on pin 3. So normal running would generate a square waveform on the 5v line. Does alfa do things differently to everyone else?

Valve timing has been checked with the correct camlobe lock tools, & tdc with a dti gauge, Both are correct.

Any input would be appreciated, as it will be a nice car if I get it running.
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"Old Skool" logic would suggest to me that fault codes 2 and 3 are a probably a symptom of non starting issue down to fault 1. Or a bad earth point at a common termination for all three sensors.

Not to sure of what voltage you are supposed to obtain but if you expect 12v instead of 5v, it would suggest either a dodgy earth cable or a break/ weak connection in the loom to that pin...
Put the diagnostics reader away and get a multimeter out to check how much resistance you are getting on the pin 1 wire in sections of 10cm or so along the loom... Then check all the earthing wires and bolt connections. Clean up as needed and re-fit... Getting low down and dirty is often the best way of finding a fault and rectifying it instead of relying on diagnostics, thats why many technicians are loosing their mechanical knowledge and end up scratching their heads!
Don't automatically assume that a new sensor is a good sensor either, they can be faulty from time to time.... Ebay is full of lamda and Maf sensors that don't work out of the box! So if you can't find a solution try a known, used replacement sensor first before buying new again...
Hope you find the problem mate

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