G'day,

My 03 4.0 Fairmont Ghia has been playing up a bit lately. It has had shocking economy the whole time I have had it (well over 16 l/100, despite the fact the trip says 11.5). Lately it has started surging under load a little and has had bad idle, I had a previous thread on this. It had coils, plugs, fuel filter 10,000 ago and has recently had the cam phasors cleaned and fuel pump replaced for a piece of mind (its done 300,000).

On a cold night last week it flat out refused to start. Cranked normally with good battery but refused to start. Started fine the next day when it was warmer. Yesterday in stop start traffic it was pissing rain and cold and the thing stumbled as it were about to die when it was idling a few times but regained its self. Then this morning after it was parked outside all night in the cold it refused to start again. I got the kettle and pored water on the throttle body, crank sensor and o2 sensor to see if it would spring into life but ran out of hot water before the ecu and was running late by that stage.

I have a bluetooth OBD2 tool for my phone and it connects to the ecu while it wont start and doesn't display any codes. It shows the manifold pressure, timing advance ect while its cranking so it cant be completely dead but it still doesnt throw a code.

Im wondering if its likely to be the ecu giving crap economy (im granny-footed), loss of power at times, rough / lumpy idle at times and this cold start issue. Does anyone know the actual issue with the ecu? Is it bad solder joints that I could just reflow? Im not keen on buying a second hand one and having it flashed when it could have the same issue as my current one. im guessing in the cold the aluminium case contracts and puts pressure on the circuit board and over time cracks the solder joints causing a bad joint?

thanks,
Jay

it sounds temperature related, try replacing air and coolant temp sensors first.

The ecu is stuffed. Mine did the same thing a couple of years ago. If it won't start when it's cold pour some hot water on the ecu and it will go.