nickgarthright Posted January 29, 2015 Share Posted January 29, 2015 Hi, I have a 1978 280z that is no where near close to passing emissions. I've retarded the timing, messed with the afm, changed spark plugs, adjusted the air bypass, and a couple of other things. What is really killing it is the hydrocarbons (unburnt fuel). The car is missing the egr equipment and doesn't have a cat. But even without those the readings make it look like a cylinder isn't firing (they all are). I need some help with getting it to pass as I can't stand not being able to drive it. Well at least drive it legally! At worst please point me to a good mechanic. I live in Gilbert AZ. Thank You! Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 29, 2015 Share Posted January 29, 2015 How close are you? Post some numbers. Details on what's being tested also. I live in Oregon and they only test idle. How many retests do you get? I can roll through the DEQ line every hour for free if I want, until I get things right and pass. A lean miss will put you over, as will a too-rich mixture. Most old 280Z's run lean, and can benefit from a little extra resistance on the coolant temperature circuit. You said it doesn't have a catalytic converter. Is it supposed to? Usually that's an immediate visual fail. Your post is generally vague. Add details. Quote Link to comment Share on other sites More sharing options...
stravi757 Posted January 29, 2015 Share Posted January 29, 2015 (edited) If you are not even close to passing I would start by looking at the water temperature sensor(located on the thermostat housing) and also the TPS(throttle position switch) If the water temp switch is bad or there is a bad connection it will cause the car to run extremely rich Proper adjustment of the TPS(located on the throttle body) is also vital. If miss adjusted it can cause many drivability issues. One cause of miss adjustment in particular is it can cause the ECU to think the car is at full throttle when the car is actually just under light cruise. This again will cause the car to run extremely rich giving very high emission when being smog tested!! Download the FSM for the year of your car here http://www.xenons30.com/reference.html This will go over in detail how to check the two items I have described. Read it patiently. Check back with us after if either of these resolve the issue. let us know what you number were on the test as newzed said. Edited January 29, 2015 by stravi757 Quote Link to comment Share on other sites More sharing options...
dexter72 Posted January 29, 2015 Share Posted January 29, 2015 Make sure the fuel pressure is good. Fuel pressure regulator is good, No fuel in the vacuum hose to the regulator. Also does it still have the o2 sensor, make sure its good. He should only get one more restest then he has to show he spent a certain amount of money for a waiver. Option that may be cheaper is to get collector car insurance on your car. And have your insurance company send you a letter stating that you have collector car insurance. Go down to the DMV and get your 5 year sticker for your license tag. No more emissions testing in AZ if you have collector car insurance. Get a policy that lets you drive the car about 2,500 miles a year. I have that on my Z. Quote Link to comment Share on other sites More sharing options...
nickgarthright Posted January 29, 2015 Author Share Posted January 29, 2015 How close are you? Post some numbers. Details on what's being tested also. I live in Oregon and they only test idle. How many retests do you get? I can roll through the DEQ line every hour for free if I want, until I get things right and pass. A lean miss will put you over, as will a too-rich mixture. Most old 280Z's run lean, and can benefit from a little extra resistance on the coolant temperature circuit. You said it doesn't have a catalytic converter. Is it supposed to? Usually that's an immediate visual fail. Your post is generally vague. Add details. If you are not even close to passing I would start by looking at the water temperature sensor(located on the thermostat housing) and also the TPS(throttle position switch) If the water temp switch is bad or there is a bad connection it will cause the car to run extremely rich Proper adjustment of the TPS(located on the throttle body) is also vital. If miss adjusted it can cause many drivability issues. One cause of miss adjustment in particular is it can cause the ECU to think the car is at full throttle when the car is actually just under light cruise. This again will cause the car to run extremely rich giving very high emission when being smog tested!! Download the FSM for the year of your car here http://www.xenons30.com/reference.html This will go over in detail how to check the two items I have described. Read it patiently. Check back with us after if either of these resolve the issue. let us know what you number were on the test as newzed said. Make sure the fuel pressure is good. Fuel pressure regulator is good, No fuel in the vacuum hose to the regulator. Also does it still have the o2 sensor, make sure its good. He should only get one more restest then he has to show he spent a certain amount of money for a waiver. Option that may be cheaper is to get collector car insurance on your car. And have your insurance company send you a letter stating that you have collector car insurance. Go down to the DMV and get your 5 year sticker for your license tag. No more emissions testing in AZ if you have collector car insurance. Get a policy that lets you drive the car about 2,500 miles a year. I have that on my Z. Thank you all for replying so quickly! The numbers from the tests are in my glovebox so I'll post them tomorrow! I'm pretty sure that there is nothing wrong with the tps sensor as I already replaced that and the engine pulls hard. I'll check that link out to determine if the water sensor is bad. As for the fuel pressure regulator; how do I check that? Also I've thought of the classic insurance for it but one of the requirements is that you have to have been driving for ten years or something and also I would definitely be driving more than 2500 miles since I live in Queen Creek and daily commute to Gilbert! Quote Link to comment Share on other sites More sharing options...
dexter72 Posted January 29, 2015 Share Posted January 29, 2015 Get a fuel pressure gauge, install it and see what the pressure is. with the engine still running pinch the vacuum line to the regulator and pressure should increase. I don't remember what stock z fuel pressure range should be. Check the regulator vacuum hose by removing it with the engine off and checking for fuel in the vacuum hose. Quote Link to comment Share on other sites More sharing options...
nickgarthright Posted January 30, 2015 Author Share Posted January 30, 2015 Here's the most recent test Quote Link to comment Share on other sites More sharing options...
cgsheen Posted January 30, 2015 Share Posted January 30, 2015 While you're checking the sensors, check the wiring and connectors - clean, clean, clean them, both sides. JavelinZ has a late 280 that he dailies and gets through emissions every year. His is ALL stock though... If you end up needing a mechanic, go see Scott - he's a few doors down from us. 1985 E 5th Street, Suite 10, Tempe. I can get you his phone number but I don't have his card on me right now. He's sorted out a few Z's that we've sent down there - both EFI and carbed. He knows Bosch L-Jetronic - very knowledgeable about vintage imports. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted January 30, 2015 Share Posted January 30, 2015 If you have a mis-firing cylinder the first thing I would do is check the plug wires and the distributor cap and rotor. You must have a California car if you have (had) a cat, but since Arizona tests to Federal emissions levels, you should be fine without it. Before you get into the can of worms of troubleshooting the fuel system, make sure the ignition system is timed and completely functional. Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 31, 2015 Share Posted January 31, 2015 Looks rich. You haven't added any details on the engine settings. " I've retarded the timing, messed with the afm, changed sparkplugs, adjusted the air bypass, and a couple of other things. " The statement above doesn't tell anyone anything. Numbers matter. Put everything back to stock including timing, Initial timing is important for idle. Verify that your timing advance mechanisms work. Advance is important for the load test. Measure timing with a light, not by ear or butt dyno. There are other tuning tips for passing emissions tests. But you need a good starting point. You didn't say if you get any retests or if you'll be testing at a shop before you go back to the state. Quote Link to comment Share on other sites More sharing options...
nickgarthright Posted January 31, 2015 Author Share Posted January 31, 2015 I can get a retest. When I originally got the car and it failed I did the things that I said I did. By the time I had done that I decided that I could just have a mechanic do it. I took it to a mechanic who said that he had worked on them before. When I got it back from him it had the readings that I posted which are the "stock settings" from what he said. I feel like it was a waste of money though because from the things I had done, only the HO at idle didn't pass. How can I adjust everything back to the original if I don't know exactly what he did? I can check the timing but besides that I have no clue how to determine anything else. Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 1, 2015 Share Posted February 1, 2015 You could use cgsheen's friend from post #8. Odds are good that he knows what he's doing. I would have verified the timing, at least, before even coming back here. Then you would at least know a little more about the guy you took it to. Timing numbers are on a sticker under the hood, and/or in the FSM Engine Tuneup chapter. If you don't feel comfortable working on engines, cgsheen's guy is probably your best shot. You're not far off, but it's the little things like cleaning connections, turning the idle air bypass screw in the AFM, checking for vacuum leaks, etc. that will get you the "pass". If you don't enjoy fine-tuning, probably best to take it to the right guy. Quote Link to comment Share on other sites More sharing options...
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