Australia, while there has been talk about roadside sniffers and the like, unless you are a company selling a bolt-on upgrade package or you otherwise wish to stick very closely to the letter of the law, you can safely ignore emissions performance.

And so nearly everyone with a modified car does just that.

For example, none of my modified cars has ever been formally emissions tested – a full test cycle costs thousands of dollars and is simply not a requirement of a normal individual enthusiast. (There are some exceptions to this – say a major engine transplant, or other mods requiring engineer approval for registration.)

That’s not to say that I consider emissions performance irrelevant – not at all. At AutoSpeed we’re one of the few publications that’s actually had a good look at emissions testing procedures (see our Dirty Stuff series starting at Dirty Stuff – Part 1 and Emissions Testing). And personally I think those people who punch a hole through their cat converters are environmental vandals. But at the same time, I’ve never felt the need to check that my own cars meet emissions.

So when yesterday I found myself subjected to a Queensland Government Transport Onroad Vehicle Emissions Random Testing inspection, I was a bit taken aback. Especially given the car I was driving…

As many of you will know, my 1988 Nissan Maxima V6 Turbo is my test car for modifications. It runs a cat-back big exhaust, a new underbonnet intercooler, increased boost, a new air intake, non-standard (but still Nissan) wheels, and so on. And right now it’s also running a veritable smorgasbord of electronics – nearly every one of the cutting edge projects that I have designed with Silicon Chip electronics magazine is in the car.

So there’s the Intelligent Turbo Timer (it monitors how hard the car has been driven and sets the idle-on time accordingly); the Frequency Switch (in this car triggering an intercooler fan at idle); the High Temperature Switch (it’s also turning on the intercooler fan and additionally triggers the intercooler water spray); the Auto Timer (pulsing the intercooler water spray when it’s running); the Delta Throttle Switch (swapping the trans mode from economy to power when I’m driving hard); and the Voltage Switch (operating the radiator fans on the basis of ECU-measured coolant temp).

OK, so none of those will affect emissions performance – but these will:

Cos there’s also the Digital Fuel Controller (which is being used in conjunction with a huge dual-intake airflow meter bypass to halve the intake restriction – it required a complete mapping of all mixtures); the atmosphere-venting electronically-controlled blow-off valve; and the load-based electronic boost control.  And in addition to that, early on I found that the standard Nissan oxygen sensor was stuffed so I’ve been running with it unplugged. (It’s impossible to get the sensor out of the manifold – it’s welded itself in place.)

So, a radically revised intake system, mixtures re-mapped right through the load range, oxygen sensor not connected, non-standard exhaust after the cat, atmosphere-venting BOV.

Hmmmm. And to make matters worse, I had purposely set the idle speed up a little so that the idle-on time provided by the Intelligent Turbo Timer (being developed on this car, remember) would better cool down the engine.

At least I’d had five minutes warning of what was about to happen. On my way into the centre of the small country town where I live I’d spotted the road block on the other side of the median strip. They’d picked the spot well – there was no way out other than past the testing station. While I checked my post office box and bought lunch, I mulled over what I could do – basically, not much. I unstuck the boost gauge from the windshield and took the digital hand controller off the top of the dash – it can be used to control either air/fuel ratio mapping or boost control, and in this case it was plugged into the boost controller. But there wasn’t much I could do about the bonnet scoop, or the bonnet vents, or the mass of exposed electronics all over the passenger seat and footwell…

“This is an official random testing emissions station,” said the uniformed man after he’d waved me in amongst the witches’ hats. “Please place your car in Park.”

Another official walked around the car with a clipboard as – I suppose – another placed a gas probe in the exhaust. I didn’t even look in the mirror – my gaze was fixed rigidly straight ahead. As I listened to the engine revving at 1100 rpm and thought about the two exposed underbonnet pod airfilters, the way I’d completely re-mapped the mixtures, and the unplugged oxygen sensor.

But then I jumped: I was being addressed.

“How many kays, Sir?” repeated the uniform. I babbled the answer – 130,000 – and went back to my Thousand Yard Stare.

A clipboard then arrived at my window and I waited for the axe to fall. But:

“Your car is fine, Sir,” said the voice.

He patted the roof.

“She’s in good condition.”

He waved me off and I kept my cool til I’d rounded the corner. Then I laughed and laughed and laughed – I bet they didn’t have another car with anything like those mods come through that day. Or probably even that week…

Of course, the fact that the car passed this (admitted fairly simple) test is indicative of both the quality of the Silicon Chip projects – and the tuning. When setting up the Digital Fuel Adjuster I’d aimed for an air/fuel ratio at idle of around 14.5 – 14.7:1 (stoichiometric, the same as the ECU is striving for at idle… normally with the oxy sensor working) and such is the precision of the Digital Fuel Adjuster, it’s certainly possible to get that.

Even with the airflow meter measuring (at idle) less than half the total intake airflow….

During tuning, the air/fuel ratio measurement had also been monitored using a very high quality MoTeC air/fuel ratio meter – in fact it was just chance that the air/fuel ratio meter was out of the car, otherwise the men wanting to sniff my exhaust would’ve found another probe already hanging out of the pipe… I don’t know what the situation would have been then – I could literally have been tuning the car with the Digital Hand Controller while the test was taking place!

Passing this random test doesn’t make me cocky – a full drive-cycle test would be a very different ask. But still, I have the bit of paper to show that the Maxima passed an emissions inspection – not with flying colours, but still passed…