my dual-fuel TW auto, 128k on the clock, has suddenly become hard to start. The battery is less than a year old. It cranks strongly. It had all new NGK iridium plugs at about 80k. Once started it runs fine. Any suggestions of what could be the likely cause would be appreciated.
I'm thinking I'll replace the air filter, distributor cap and rotor.

Is it hard to start on gas or petrol?

Start on petrol, and don't let the fuel level drop too low or the fuel pump will bugger up.
If it starts ok on gas normally, run it on petrol once in a while.
If it runs ok once started, don't bother replacing the air filter, distributor cap or rotor as these would affect the car once running. Best identify the problem before you go replacing bits needlessly.

it's factory gas, set up to always start on petrol regardless of how the switch is set. I run it on petrol occasionally and I keep the petrol tank over half. None of this relates to the hard starting.

Best identify the problem before you go replacing bits needlessly.

any suggestions as to how to do this?

is there a chance the fuel is so old it's gone stale?

no the petrol is fresh

How exactly does it start ie

Does it crank abnormally long the all of a sudden start perfect and normal, or

Does it kind of splutter to a start?.....

How exactly does it start ie

Does it crank abnormally long the all of a sudden start perfect and normal, or

Does it kind of splutter to a start?.....
sorry to be vague, but it's usually the former and sometimes the latter

Videos please

does anyone know what's the usual life of the distributor cap and rotor?

I daresay it should be done every rear spark plug change.

mine has done 170 000 k with no issue but to be honest could do with a refresh

does anyone know what's the usual life of the distributor cap and rotor?

I have over 200,000km on mine and its still going good. I went looking at the wreckers for a better one but only found ones with far higher mileage on them that looked more worn than mine. I suspect they were still working well.

I have over 200,000km on mine and its still going good. I went looking at the wreckers for a better one but only found ones with far higher mileage on them that looked more worn than mine. I suspect they were still working well.

does anyone know the part numbers for the rotor and cap? I'll order them off amayama.

I got MD619274, MD619126 for US model, Jap F36 wagon also MD619126. Not sure what the difference is, dealer may be the smarter option for the numbers

but in the parts list thread reported
Genuine Distributor cap for 3.5
MD619511

Genuine Rotor for inside distributor for 3.5
MD619274

http://www.aussiemagna.com/forums/showthread.php?t=39415&p=1595155&highlight=MD619274#post1595155


probably no savings that way, Might be worth checking local or aftermarket bosch

thank you!