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Discussion Starter · #1 ·
I was told when I bought my car that the smog test it passed during importation would be the only time I'd ever have to do it. However, laws constantly change in Korea, and I do need to think about how I'd go about making my car pass a smog test - no easy feat, as my exhaust will make your eyes water and make you look like you've got conjunctivitis - and sadly, this is not an exaggeration!

So I'm thinking - well, I'd have to recat the car, with a new cat probably. Should I reinstall lambda sensors and turn O2 feedback back on? One problem is that, when I got smogged in California, they tested the car at idle, then revved the car a bit. In Korea, the car goes on a rolling road and is driven at 40-50kph to simulate actual driving conditions.

This also leads to the basic principle of how to safely make the LEAST possible amount of power. I'd set the fuel cut limiter at, say 4000rpm. I would want to cripple the turbos - would I need to find a way to keep the wastegates forced open? Maybe remove the actuators and just install a fixed-length bolt?

To get the cleanest emissions, including NOx levels, what is the target air/fuel ratio? Mapping for cleanliness would be the most interesting map job I've ever done...I think I'd want to run a little lean, say around 15:1. I need to keep the turbos offline as much as possible because I don't want the technician trying to boost my car for even a second with that lean an AFR on a rolling road.

Basically, I just need to know the "cleanest" AFR, then map ignition and try to rig the turbos so that there's no danger of knocking.

I won't drive to the test center either - I'll flatbed it there, get it tested, then flatbed it back to the garage and reverse all that shit and get my car smelly and powerful again :D

And thinking about this, I give serious kudos to modern factory mappers. The Evo X the missus is getting - that's 150bhp/liter output, yet I stuck my face directly into the exhaust and smelled absolutely NOTHING!!
 

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Discussion Starter · #3 ·
anyone have a target AFR for cleanest emissions? Just go stoich?
 

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my gtr is going for its emissions test this friday, im freaked out, im putting the cat back in before it and make sure its nice and hot going into the test,

i dont know what im gona do if it fails, is there anything that can be easily done through the fc commander to alter the emmissions?
 

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Discussion Starter · #5 ·
k, I've done a little research and this is what I've got so far:

- cats good. more cats better. cats must be hot. I've seen multiple cats in Korea, as well as stuffing the exhaust pipe with platinum-plated mesh, rolled up.
- set the whole damned map to 14.7:1, then adjust fueling with a wideband.
- stoich is a really bad AFR for being on boost, so the turbos must be somehow taken offline. If the ECU is a MAP...then maybe I'd just stick an air filter on the plenum? Haven't thought of a MAF solution that wouldn't require adding new custom pipes.
- I haven't done this yet and it feels rather risky to me so note that I AM JUST STABBING IN THE DARK for ideas!! But set the rev limiter as low as possible, below boost threshold if possible. Timing should not be too retarded, as the fuel-air mixture needs enough time to burn. A 15:1 AFR would play it safe in providing enough oxygen to keep HC and CO to a minimum. Hot and lean produces NOx, so perhaps one way to do it is to run lean and then run water injection to keep things cool?

Like I said, just brainstorming here. Setting the entire fuel map to stoich feels like engine suicide to me, but perhaps it can be done with the right ignition timing and no boost. In essence, what I've gleaned so far is that you need enough oxygen in the fuel-air mix to make sure every molecule of fuel gets a chance to burn (reducing HC) and enough so that CO2 forms properly, without going so lean and hot that NOx starts forming. The cat is supposed to help the proper reactions occur that didn't quite make it in the combustion chamber.

Oh, and heated, finely atomized fuel will further reduce unburned HC counts.

I would have a pro tuner set all this up; I don't even know if it's possible to run an RB26 at stoich across the board, without melting or blowing a piston.

Or maybe, depending on your car's tune, swapping in a bone-stock ECU and a cat or two may allow the car to pass, provided boost is kept VERY low (airflow, not boost pressure, same as stock), because I presume the stock Skyline could pass emissions.

again, please have a pro do this work, I'm the farthest thing from!
 

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I wouldn't be too concerned. There is a good possibility the testing machine would be 2wd only, meaning just a 2 speed idle test for the gtr. Also, the government may impose an exemption for older cars.........
 

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If you can get away with disconnecting one injector for the test and raising the idle... voila, you have an instant air pump to dilute the exhaust gases.

This is a trick I use for passing emissions with my AE86 with full race engine (304 cams will never be environmentally friendly lol) through Japanese Shaken. :D
 

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Discussion Starter · #8 ·
nice idea :) makes running a little lumpy though, doesn't it?
 

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Why would turbos be on boost at 40-50kph at below half throttle?

You can be in 3rd/4th gear and be in 3000rpm and have no boost whatsover at half throttle.

Leave the on boost part of the map alone and map off boost areas only. You woudl also be better to drive it there as it will heat the cat up as well as get the engine to operating temps which means not lean.

15:1 Is no problem at all on the cruise area of the map where you should be on the emissions test, I wouldn't think they would do it in 2nd gear, at least third gear. I am not sure what is acceptable in korea but in the u.k you can pass between 13.9:1 and 15.2:1 so you don't have to tune to 15:1. You could jsut tune to 14.4:1 and still pass.

Out of curiosity what is your a/f at the moment?
 

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Discussion Starter · #10 ·
13.5-14 at idle, 11.5 at full boost. I reek of petrol whenever I drive the thing. I'm not sure if that's just from fuel tank vapors or horrifically high HC emissions.
 

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Discussion Starter · #12 ·
used to, but now an electronic smoker (e-cigs)...totally the bee's knees!
 

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my a/f's are somewhat similar.

I am around 13.9 at idle only because of the cams and it soundling like it wants to die if any leaner lol.

On really light cruise its around 14.5-15:1 and then towared the start of boost and the first few psi it is 13.3-12.8.

Once properly spooled up and after about 4,000 rpm it progressively settles at 11.6:1.

I think you should lean cruise up a little to aroudn 14.5-13.9 if the car behaves fine in that region, if you are "afraid" to go to 15:1 as you are just wasting fuel.

My car does not reek of fuel but has that exhaust fuel smell if you stand behind the exhaust but that is normal with any car even new ones. I certainly don't and neither can you smell it in the car.
 
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