monk3y Posted May 15, 2015 Share Posted May 15, 2015 So I'm having a bit of an issue getting my 280z with stock fi to pass emissions in Oregon and I can't seem to nail down the cause. On my last test I got Hc 279 and Co 4.9825. The hc is close but the CO is way off. Thus far I have gotten a new cat, adjusted the valves, replaced the plugs, changed the oil, change the cap and rotor, coolant temp sensor, changed the filter. Anyone have some insight on what I might be missing? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted May 15, 2015 Share Posted May 15, 2015 Looks like you are a bit too rich. You could have a leaky injector or a mis-adjusted airflow meter. You are running a catalytic converter in Oregon? Even Federal 280Zs would do better than 2% CO. Have you checked your fuel pressure? Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 15, 2015 Author Share Posted May 15, 2015 That's the only two things that make sense. The injectors aren't but a year or two old. I cant figure out how to get the afm adjusted right eve with the documentation. I put a brand new cat in the thing two days ago and nothing. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted May 15, 2015 Share Posted May 15, 2015 If you can fit a fuel pressure gauge to the rail, I would check the fuel pressure. As well as making sure the vacuum line to the regulator is tight and not leaking. Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 15, 2015 Author Share Posted May 15, 2015 I know that vacuum line is fine, I checked. I will give a fuel pressure gauge a try tonight and see where that gets me. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 15, 2015 Share Posted May 15, 2015 I cant figure out how to get the afm adjusted right eve with the documentation. What are you adjusting here? Hopefully, not the vane spring. Since they only measure idle you just need to lean things out until you pass. You didn't mention timing either. Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 15, 2015 Author Share Posted May 15, 2015 They also measure at about 2000rpm so it can't just be lean at idle. I set the timing to 10 btdc and I also tried 5 btdc. No dice. It has to be something else. Quote Link to comment Share on other sites More sharing options...
Spooky_Intentions Posted May 15, 2015 Share Posted May 15, 2015 Well if you want to fix your car then youre getting great advice and youve done a lot of troubleshooting already, if you want to pass emissions just so you can use it as a daily drive(which i had to do at one point) i just put some E85 fuel in the gas tank, about a 50/50 mix of E85 and regular, then passed with flying colors. Your car will run like crap so just put some premium in afterwords and youll be fine. Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 15, 2015 Author Share Posted May 15, 2015 Someone actually gave me that recommendation. I may do that if all else fails. I need to use the gas in my car and if no fix by then. I will do that as my tags are expired. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 15, 2015 Share Posted May 15, 2015 They also measure at about 2000rpm so it can't just be lean at idle. I set the timing to 10 btdc and I also tried 5 btdc. No dice. It has to be something else. Must be more stringent in other counties. Too bad. You didn't say about the AFM adjustments. You also didn't distinguish between idle results and 2000 RPM results. What are the limits for the two tests, and what were the results for each one? Adjusting idle emissions is a completely different thing than adjusting throttle open emissions. Timing is advanced, if your vacuum advance hose is connected correctly and the distributor isn't screwed up, and the throttle position switch is different with the throttle open. You can get some pretty direct help if you add the details. Or you can go with the one time magic potion. Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 15, 2015 Author Share Posted May 15, 2015 I was wrong it's just an idle test they just make you Rev the car up to 2k RPM for the 2nd pass. I leaned out the afm a bit by adjusting the cog. To pass I need a 220 hc and a 1 CO. I was getting 279 HC and 4.9825 on my second pass. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 15, 2015 Share Posted May 15, 2015 Put the AFM cog back where it was and turn out the idle air bypass screw instead. That's why it's there. Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 16, 2015 Author Share Posted May 16, 2015 Well did that and tosses in some seafoam just to give it a shot. It scored worse with a 313hc and a 6.7297 Co. They are listing the displacement as 2.4 for someone reason. With as rich as its running e85 might not be good call. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 16, 2015 Share Posted May 16, 2015 Seafoam is a can full of HC, with a little bit of rubbing alcohol added. And a ton of sales pitch, all in a neat looking can. You're in the common bind of trying to find a quick fix and ending up worse off with no easy way to get back to where you started, Keep track of where things started and what works. The details are important. Does "did that" mean putting the AFM back where it started or turning out the idle air screw, or both? Did you turn the screw out 1/2 turn or 5 turns? The EFI system requires some rigor and patience to get right but many people get it done. Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 16, 2015 Author Share Posted May 16, 2015 The seafoam I used was the spray stuff it didn't go in my fuel,just the intake. I did both of those things and it's no better off. So think the problem has to be elsewhere. Either a leaky injector or maybe an egr issue. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 16, 2015 Share Posted May 16, 2015 You might get lucky and pass with random adjustments and part replacements. Most people just end up totally lost. Even with carbs you have to know how many times you turned an adjustment screw. Numbers matter. Try the Fuel Injection Guidebook. 1980 version covers all years. You'll need a meter. Start with the coolant temperature sensor. http://www.xenons130.com/reference.html Good luck. Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 20, 2015 Author Share Posted May 20, 2015 (edited) Well I just ran a compression test and I think I found my issue. I was hitting about 115-120. What's weird is it doesn't feel down on power. I double checked my readings too. Edited May 20, 2015 by monk3y Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 23, 2015 Share Posted May 23, 2015 (edited) Most adjustments on the AFM render it useless. Have you checked your TPS to make sure you're rich at idle? If you run lean, your number go haywire from misfires. The cat is rarely at fault, and that fixing it would point to gross errors in the upstream systems. As stated above federal cars without cats easily should make 2.0%, and the Nissan upstream diagnostic limit is 3%. In other words a fail on your car big time! Truthfully, at idle the cat is cold and shouldn't really be doing anything at all... CO on a properly running system is generally at around 1.5~1.7% without a catalyst What is your vacuum at idle? Start there. If it's not 17-19" minimum, get your valve adjustment, timing and idle speed right. Generally idling higher is good as they tend to load up and misfire. If they have an upper limit on idle speed (in CA at one time it was 1,100 rpms, so you would set idle at 900, 950, or 1,000 to get best vacuum, and then go from there. Did you get the right injectors? Sure you didn't get Turbo Units instead? That would over fuel your car but not puf black out the back... That compression is 15-20# higher than mine and I pass fine. You mention EGR, which again should be off at idle and only slightly active at 2500. Normally that shows as a NOx high fail on a dyno test. Low compression would naturally lower NOx though! If you have a vacuum leak through the pintile on the EGR, from corroded EGR passages, leaking diaphragm...that could affect manifold vacuum to raise fuel pressure and run rich. The system is VERY dependent on having 17-19" Hg Vacuum in the manifold at idle to drop the fuel pressure 8.5~10 psi. If you got vacuum leaks...that will do it as well through a combination of lean misfire or rich condition from the FPR bias being off. Edited May 23, 2015 by Tony D Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted May 26, 2015 Share Posted May 26, 2015 That's excellent advice. Monk3y, you will do well to follow that systematically, then you will find what is causing the problem and get it fixed. And your car will run better as a result. Quote Link to comment Share on other sites More sharing options...
monk3y Posted May 29, 2015 Author Share Posted May 29, 2015 I double checked my compression test and it was hitting 160 so I am idiot in that respect. Thus far I found out all the plugs are equally black. I was about to run a fuel pressure test when someone broke into my garage and stole pretty much every tool I own. I'm starting to think the fuel pressure regulator may be at fault here. I am pretty positive my injectors are right for my car, It was running fine on these injectors till recently. I will test vacuum pressure when I can get a tool to do so. Quote Link to comment Share on other sites More sharing options...
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