As some of you know I am taking my car through the registration process here in SA, and as a part of this I need to pass the IM240 test. I am after some assistance from anyone that has taken their zed or VG30DETT throught this, as such this will be probably aimed mainly at the NSW guys (and more psecifically John at UAS). I had the test done yesterday and failed on the CO and NO. but it was very close. I was after any insights in regards to the tuning that could help, get the car through. I was not keen on their first suggest which was to put the nissan ECU back in, as it is clearly running cleaner than that and it is a non-logic grasp in the dark at a fix. I know this is not a zed however, noting that this is all to do with the zeds engine and the registration in SA I am sure there are going to be some valuable lessons for all.
NO is from the combustion temperature isn't it? I assume you are using the EGR? There was a thread about a guy on SAU who got his skyline to pass the IM240. I'll try to find a link for you.
Found it. This thread: http://www.aus300zx.com/forum/showthread.php?t=293540&highlight=IM240 This link to SAU http://www.skylinesaustralia.com/forums/Emission-Testing-Modified-t155081.html
Thanks Mitch a very interesting read. I have been running through the data logging of the test. It is a very finite line for the throttel control, as the maximum TPS was 12 % and most was 2-6%. I did find something strange in the tune though the sequential injection is 400degrees BTDC. Noting the injectors are almost directly on top of the valve I thought 360degrees would be the latest, even closer to 350degrees. Anyone have any advice on this?
CO is unburned fuel, there is a mention in the FSM about a resistor to bypass the coolant sensor as part of the CO test. The purpose of the EGR is to reduce NO, so that'd be worth checking. If the EGR valve is OK the outlets of the pipes that connect to the intake manifold can be blocked or restricted. What were the test readings?
Thanks for your insight, my VG30DETT is pretty modified. It has a link G2 ECU, an improved crank case ventilation system, denso top feed injectors, electric water pump, four cats. I agree the EGR (if fitted) would address NOx, however only on the low vacuum cycles, were the NOx is an issue during the accel phase, and the exhaust gases would drive up the CO which is my biggest issue. As for the result I achieved I just gone through my notes jotted in my bluebrain (blue not book) that on one of the tests the car achieved HC 0.21 CO 4.63 NOx 0.92. and O2 20. O2 number might not be right as my writting is so poor I have trouble reading it. I didn't get a printout, as it was not going well on many fronts. There are a few items that need to be addressed as a matter of course too. The idle was very poor when cold, and the fan belt was slipping on the cold cycle tests. This showed up in the data logging as well. I'll keep going through the data logging, and will share anything I find (especially if it is the magic pudding for emissions).
A quick update been playing with retarding the ignition timing, changing the injection timing function from a set sequential to a RPM based timing sequential. We have had some success in reducing the emissions. However, we are not at the point where we are considered a pass. There is a fair amount of NOx being produced under acceleration. Also, the HC and CO spike during the initial taking off from stationary. We are going to give it one more go tomorrow morning, with a final test before lunch. IF this doesn?t work, it looks like the final option is to, cut out the exhaust catalytic convertor setup I have already, and put in a couple of Holden EURO4 cats. And, hopefully they will do the job, as that is my last ditch effort. Unless someone knows some better quality three way cats, or a tuning solution??
i got my car passed(laser), i had 2 metal cats. and a good O2. there was a tuner in syd who passes cars, he tunes the cars and takes them. one trick is to get 2 brand new cats. take the car by truck and put it straight onto the tester, dont start the car with the new cats. IM240 is hard to pass.
I was wondering if putting multiple cats in sequence would help, I have very limited room. In the back of my car so it might not be an option. I am concerned the Holden cats might not work either . And, yes you are right IM240 is very hard to pass.
look on the bright side, you guys have it easy, in perth an IM240 test costs around $800 pass or fail and you keep paying that amount until you pass. fortunately they put a hold on the whole system here for a while.
Well the car is very close, but my problem is now that the cats are not getting hot enough to light off, until very late in the test. Not done yet. But it might require exhaust MkIII
Could it be that you are triggering your acceleration enrichment map when taking off? You might not need as much enrichment as you have in your map (Yes, its me, from that.... other forum). Try decreesing it until it stutters when you kick the throttle, then enrich until it doesnt. Thats all you need. The rest is just wasted fuel which could show up on your test as CO and HC. Bring up your fuel runtime values and look at them. They will tell you if the Acc Enr kicks in. Ie your accel sensitivity value is pretty high (50)
Thanks Steve, we did play with this, maybe I need to go further. I accutally thought the sensitivity goes the other way?? the high the number the less sensitive to throttel changes. If that is the case it could be half the problem with those initial take off spikes. But we measured the cats and they don't get above 150degrees celcius, and if they don't light off we are struggling. Basically trying to meet emission standards without cats!
Bringing the cats up to temp is the role of the AIV system i believe. Introducing air into the catalyst will improve warm-up time. May be an avenue of exploration.
Test results Thank you everyone for some very good points. I have attached the test results (sorry it was a screen shot of the last tests). And, after a little confusion (and, tears) it has been confirmed that I have to pass the IM240 overall test result for registration. The Yellow line is the speed versus time path the test driver needs to follow. Test results for HC 0.791 (required < 0.6g/km) Test result for CO 14.84 (require <10g/km) Test result for NO 1.502 (require < 0.502g/km) These latest test were when I found out the cats were not even coming up to temp. Using an infra-red temp gun we measured the cells (you can see them up the end of the pipe) they were only 250degreesF. And, it is my understanding that we will not see light off until they reach 500-600degreesF. It this is correct it certainly goes some way to explaining the absolutely disastrous results compared to the first test. The exhaust goes to a 3inch exhaust straight after the turbos, before the resonator and finally the cats. The P=VT equation still rings in my mind now from my uni days and too much heat is lost in this expanding area. As such the cats are just not coming up to temp. Whilst, they are after markets cats, which are renouned for not working, they are 300cpi and have been proven in documented testing before. The after market computer, a Link G2, has just about every feature you can think of (injector timing, to air temp fuel/air maps). In addition I am controlling the crankcase venting to ensure that it is flashed off in the peak cycles of the engine. I fail to see how a standard Zed would pass with the original ECU, sensors and injectors. I am loathed to change out the exhaust, as it took me a very long time to design a resonating arrangement that passes the noise requirement, at the same time gave a nice note and reduced back pressure. However, if I am off the mark then so-be-it, and I?ll address it. But, I can also try winding a little timing out, and reducing the fuel. This will drive up the exhaust temps. However, this increase the possibility of having disastrous effects else where in the engine?s maps. Will keep every one up to date, as rest assured I am sure there will be a few more people doing this test soon. Especially noting that they sending may off many owners for this test as a part of defects, in all states now!
I just had a thought. EGR is usually added to the system to keep Nox emissions under control by reducing combustion temp. The reduced combustion temp stops any Nitrogen being cracked creating the Nox issue. The second EGR in the engine is via valve overlap. Increasing valve overlap is a form of EGR as well. Was going to suggest you disconnect the VVT and rerun the test. OR connect the VVT so it is running all the time. ( I am not sure which way will work best) This may just be enough to get you across the line Dave. If you dont have VVT on the engine ( cant remember if you pulled it or not) Maybe resetting the cam gear position may do the trick.
Dave you probably have researched this way more than I have but I do remember reading on several occassions that temperature is the key to passing an IM240, and you can go from being fine to failing miserably based on this alone. Given the somewhat unscientific nature of the test you should be able to warm up the car before testing as I don't think there are any conditions with the IM240 as to what state the car is in prior to testing. A lot of people have found this is the key to them passing. I assume I'm telling you things you already know but just throwing it out there Ben
