Oh yea, sorry i forgot that in my reply. Tyre valves are pretty good so it doesnt drop much over time. I probably check it every month or so.

Just filled up again before i interrupt the measuring with highway driving tomorrow afternoon.

I will have to check it over a whole tank starting after the weekend, but from the last few days it seems like changing the fuel pressure regulator with the old xr6 unit i had lying around may have dropped it again to around 15 -16. More to follow on that i guess, though it may still be totally rubbish.

I have noticed some smoke on cold starts recently, but only briefly. Head gasket isnt too old and she doesnt overheat so i would guess its just a bit of oil.

I've had issues with VDO and other non specified o2 sensors. easy way to diagnose it, just unplug it, if nothing changes there is a contributing factor. I would like to think that would solve all your issues, but I think it may just be an underlying factor that are a few issues.

Not going to hurt to try though right?

For sure, its definitely worth eliminating it before moving on. How can i expect the car to run without it though? What data does it use to calibrate mixtures etc? Cheers, Andrew

Okay, one bosch o2 sensor and one bosch coil ordered for fitting next week, for the sake of eliminating causes. When i do those i will check all the vacuum hoses thoroughly.

The weekend's 230km of mixed highway and heavy traffic in hot weather ate up 44L. So all up about 19L/100km combined if i worked it out right.

Checked the lines, tank for leaks or splits and i couldnt find a thing, although it does smell a little bit of fuel under the lift up floor in the back.

One thing i was thinking about though, what sort of RPM should I expect in a sohc/longreach at 100km/h? Standard diff, I cant quite recall what. Anyway, mine sits on about 2000 which seems a little high. Makes me wonder if this running state is sapping a lot of power from the motor as well.

cheers, Andrew.

Your RPM @ 100k is about right. The diff will most likely be 3.27:1.
Relocate the coil to in front of the dizzy area - since your replacing it.

Might be worth pulling the ECU fault codes to see if anything stands out.

Yeah it is a 3.27 diff. I should be able to gather some loose cable and connectors at work. Are there any common fubars i should watch out for? Seems pretty straightforward really.

I was going to get any codes pulled if i take her into an auto electrician to check out the IAC issue. Speaking of which, is there a fuse or relay that can cause IAC problems? Ill have a look in my manual a little later, but i know that more than a few people here have dealth with it before haha!

Being a bosch coil, it'll most likely have an extension loom with it.
Pretty easy operation to do.

You can pull the codes yourself - view the tech docos.
You need to remove the lower dash panel (around the handbrake and lower steer column) to access the diagnosis connector near the fusebox.

Your fuel economy reminds me of mine before I started fiddling with it. I would use about half a tank to get to my brothers (200km of straight highway driving) and with a 68L tank 34L is abit much to use. I'm now down to 8L/100km. To get that I replaced my o2 with a Bosch (which helped alot), replaced fuel filter (it helped a little), replaced coil (helped a little), replaced fpr (helped alot) after that I got 10L/100km. I got to 8L by replacing my fuel injectors with au ones that were cleaned before fitting (the old ones were cleaned to see what they were like and they were clean because I cleaned them before hand). This is in a fairlane with a 3.23:1 lsd diff ratio, full 2.5" exhaust with 100cpsi cat (the exhaust helped abit with economy probably due to replacing 3 mufflers with 1), I replaced my clutch fan with twin thermos, I use 95 octane fuel with 5 degrees advanced timing, au headgasket (very slight improvement in economy), adjustable shift kit (helped abit) and a j3 chip to suit everything I've done to it. I hope some of what I said can be used to help you with yours but using Bosch parts gave the biggest improvement by far. I get about 15.4 in town.

Thanks for the reply 90na2. Ive checked a lot off that list myself, so hopefully these last few things will make a drastic improvement.

A bit of upside down under the steering wheel time this afternoon gave me a few new leads as well. Though the car wasnt running (was looking for something else) the brake booster shaft seal looks pretty damn average, i will have to check it out next time I'm driving. I have read that a faulty booster will likely produce a rich condition as well.

The something else i was hunting was the source of water dripping on my feet. Seems to be coming down the felt insulation on the RHS wall above the wiring. May be time to have a good look in the plenum chamber, as i dont much like having water dripping over my delicately taped wiring.

Said wiring is a total mess. Being an ex police car there is just s**t everywhere under the dash. Unless thats just a falcon thing... I have loose ends, random empty plugs and sockets and who knows what else to scratch my head over.

Random plugs and sockets sounds about right my lane has a few. Being ex police yours may be tuned to parts you don't have any more because the cops removed them. It may be worth looking into.

Random plugs and sockets sounds about right my lane has a few. Being ex police yours may be tuned to parts you don't have any more because the cops removed them. It may be worth looking into.

New coil and oxy sensor fitted. I ended up keeping the same coil position as i was fitting them after work and to be honest i found it fairly easy to change out. A bit awkward for sure, but a small socket set and small hands got it out quick enough.

Anyway, I'll keep an eye on the fuel. I was hoping the idle shudder would subside but not so lucky.

So... timing and vacuum checks i think.

Oh yeah. I forgot to mention I've also noticed recently that instead of vapour/regular condensation on startup my tailpipe has been spraying out lots of black waterdrops, presumably black from the heavy carbon all through the exhaust. No oil or petrol smell in this moisture and I havent been using any water. Definitely worth noting though i do have some bad exhaust leaks (fr/back flanges of cat, after sensor).

In other words she just sprays my fuel money all over the driveway, im guessing this is a pretty good sign of rich running.

One thought, while i was changing the coil i took some time to inspect a few more things on the manifold. On the plastic fitting at the no.6 end, what is the tube next to the MAP sensor hose? The thin plastic one inserted into a rubber boot.. I did find this was sliding inside said rubber boot very easily, enough that i could easily suspect it to be leaking.

cheers, Andrew

"no.6 end, what is the tube next to the MAP sensor hose? The thin plastic one inserted
into a rubber boot.."
Vacuum line (source) for the indash vent control... which is why the vent control
will default to blowing only onto the windscreen if the plastic hose pops out of the
rubber boot (yeah, they're all a loose sliding fit, even trying to clamp with a cable tie
doesn't help much).
Incidently, I believe the vent control can go vacuum leaky internally also..., at least I
suspect that's why, in the XG I'm driving, it takes about a full 10 secs for the vent control
to stop blowing to the windscreen, whenever I set the fan going & place the rotary vent
control to anything other than 'windscreen'...