VZ Alloytec 175kw Runs Rich

[thumpernz]

This is my first post on JC, but have been lurking for a while, I have a problem with the VZ Alloytec 175kw ute running rich and generally using too much fuel, especially when cold. Another thing it does is it sounds like it has an exhaust leak when cold running, which goes away whem normal temp is reached, but we have checked and cant detect a leak.
This all started when the LH catalytic converter contents broke up, and were rattling so much we had it changed out, the dealer said that an aftermarket CAT would be ok. Since then, the engine when cold stinks of fuel, does not run right, sometimes cuts out when started, but can be restarted ok.
The general economy around general use, which mainly involves open road use, is 12.7ltr/100km. Trip economy is around 10.0ltr/100km. I have had one of the O2 sensors changed as it was said to be lethargic, and each time it has had flash type work done, it runs ok, without the fuel stink, but it goes back after a week or so. Could this be a faulty computor? I have had unexplained faults like the lights failing to turn off, and once it flattened the battery completely. The ute has 78K on it, and generally runs ok otherwise.

[2005vzute]

wow, sounds similar to my ute, my fuel atm is 13.8l per 100km with an average speed of 27 i think it was...i was thinking maybe vacuum leaks and ignition have been causing a rough idle on it, when i get a bit of money i might start doin abit of muckin around with replacing plenum gaskets n stuff..i have the exact same exhaust leak, when it's cold, you can hear it..at normaly operating tempaerature, you can't hear it...im pretty sure mine is a new U-bolt clamp thingo needed where the pipe connects to the resinator, im pretty sure the thread is ****ed on mine...and them bloody headlights, i keep mine on auto, and one night my old man said to turn them off, i was like :S wtf...its done it a couple of times now, not enough to drain the battery, but it's still not right, plus my utes done about 74 500 kays...whats the go ay...very interesting to find out whats up