Stupid Stupid questions.... but I have no idea.....

with a stock DP, and Exhaust would a UTEC be able to pass emmisions with 272 cams?

I live in MD

-Shahul

 

Probably.. you might have to do some tweaking though an "Emissions Map" Possibly some adjustable cam gears so you can play with the overlap in the cam's timing (-4,-1 I think was recommended) to even out the idle, when you do that you can reduce the emissions too..

 

Dang, I thought everyone handled OBD-II emissions test the same but I guess not.........Glad I live in Georgia.... Since the evo is OBD-II all they do is plug in and check for codes, no sniffer test at all.

 

In NY State, I think its a similar setup, but I do think they do an sniffer check at Idle since the Dyno's used here are not all wheel drive. I do know the first inspection after you first buy the car (one year after you buy) here is safety only... The dealer said the following year they use the sniffer and OBD-II (BTW Our VIN# for the car is actually on one of the OBD-II PID's, I don't know what other juicy info is in there since I haven't scanned every single pid#)

It may be that they do a sniffer after the car is a few years old at different states..

 

so maybe running richer?, using Silver Surfer's -4, -1 (or -1.5) may make it easier to pass....

I just dont want to get the cams, Utec etc, and not pass emmisions

-shahul

 

We'll I'll find out.. I already have the components and am just waiting to get my car serviced and getting it back (My shifter "Jammed", the rails in the transmission, seized up, probably the same 5th gear TSB issue I had the first time with the synchronizer and fork) I may insist they replace the entire transmission, and have them give me back the old one, so I can send it out to have it "built" (If I have to pay for it, I'm DEFINITELY getting the old one back and insisting they replace it, assuming they cannot honor my warranty, but this car isn't abused so I don't see that an issue)

Anyway, Back on topic.. You need to add a bit of fuel with the cams anyway, if your idle is maintaining a 14.7 or so AFR in closed loop, and you can reduce the cam overlap using SS's cam timing suggestion, you can reduce the 'unburnt fuel/emissions' significantly at idle..

I do plan on running the -4 -1 timing, and I have 680cc injectors so I have to scale my tuning.. as soon as its done, I'll have a friend put it on the sniffer and find a good setting that will 'sniff happily' so it will always pass. I'll post the info here obviously, but its several weeks away.. I don't intend on swapping my exhaust out, but I do have a Catco 3" Cat.. So you might want to go that route.

 

so what happened?

-shahul

 

It passed no problem.. If your car fails, it won't be because of the UTEC.. the advantage is you can tune it to provide a decent sniffer result.. I still recommend keeping EGT's low and reducing the cam overlap with the timing gears.. Oh, and run a Cat.. its what will help the most..

 

From my experience, the stock cats work way better than aftermarket for the sniffer. Cats like heat, and larger high flow cats don't do as good of a job retaining heat and reducing your HC counts. If you're going to try to pass, slap the stocker back in if possible.

 

I am definetly puuting the stock exhaust on to pass.... I guess im just worrying for no reason?

-shahul

 

I actually tried passing smog on my 98 GSX w/ 272s. I didn't have adjustable cam gears so I couldn't dial out the overlap. Well, let's just say it blew the numbers away. Everytime the idle loped, the HC counts would shoot straight through the roof. The limit was 100 ppm, and mine would fluctuate between 400-1200 ppm at idle. I did have a bad cat also, but you get the idea. If you can dial out the cam overlap w/ cam gears, then you should be able to pass smog w/ the 272s.

 

This is a difficult thing to explain, but Mark is correct.. like I said earlier, dialing out some cam overlap will reduce the loping somewhat.. the big problem is going to be the aftermarket injectors since you'll go pretty rich when it does supply fuel, to pretty lean when it stops especially at idle.. so you need an efficient and functional cat to catch it.. thats why getting rid of the lope is so important, you don't get the overlap which lets unburnt fuel out..

Although it may not be necessary to replace your aftermarket exhaust and cat with the stock setup for an inspection (some aftermarket cat's do work well) It might be necessary to swap a set of stock injectors back in this way you get less fuel going in at idle.. big injectors are hard to control for very low duty cycles and low fuel requirements..

Thats why its so important to match your injectors to your actual fuel needs.. especially on the street... think about it.. if you have a injector thats 50% larger than stock (750 or so CC) its also providing 50% more fuel at the same duty cycle at idle.. what does that mean? Real rich.. and when it runs in closed loop, you'll see the engine idle swing up and down as it tries to maintain stoich.. it also means in open loop (when its first started and cold) will run either very rich, or very lean depending on the MAF reading since 1% or 2% duty cycle will literally either be on or off with bigger injectors.. so how do you fix that, add fuel so its consistently being delivered.. unfortunately that results in basically a stinky rich condition at idle which will likely go off the scale during a sniffer test..

So, what relevence does that have to reducing cam overlap? Reducing cam overlap means reducing the loping at idle, the result is increased idle vacuum.. increased idle vacuum means higher MAF reading at idle and higher airflow through the engine, therefore slightly more fuel required for the air, hence balancing the equation.