I am calling on all the Z owners that have any "Tricks" about the Z to help tweak it for emissions. I Bought a 1990 300ZX TT 5 weeks ago. Flew down to Georgia to pay for it and drive it home. Only to find out that once I got down there the car did not run. The guy told me it was mechanically perfect. If it was it would have ran I thought. But thats a story for another day. I had my tools Fed-Ex'd overnight and within a day I had it running. The car passed Georgia emissions when it ran down there, but unfortunately in CT it did not. These are the test results from the 1st emissions test. "HC (RPM) 324 allowed by CT 100=Fail, CO% 5.08 allowed by CT 0.53=Fail, and NOx (RPM) 0 allowed by CT 1167=Pass. So I only passed 1 fo 3. Since then I have replaced the Exhaust including mufflers, cats and O2 Sensors. I just had it checked again today and these are the new results. "HC (RPM) 96 allowed by CT 100=pass, CO% 2.71 allowed by CT 0.53=Fail, and NOx (RPM) 321 allowed by CT 1167=pass. So 2 out of 3 this time. So it is getting better but still not there. I am assumeing that the high CO% is attributed to running to rich on gas. So what can I do to get this thing down where it needs to be? Could it be some of the mods on the car doing it? My car has a Rebuilt JDM engine, New seals in the turbos, a Apexi boost controller (which I am still unsure how to use) D/C Blitz turbo timer, A Jim Wolfe stage 3 upgraded ECU, Laptop intergrated with nissan datascan software, HKS BOV's, K&N air intake, Turbo Fuel Pump, New Injectors, Pop charger, OEM cats thanks to RDZ, N1 cat back exhaust, 4 puck stage 3 racing clutch, fidanza short throw shifter, Z1 hard turbo intake pipes, new coil plugs and coils. I know alot of this stuff does nothing mechanically towards the emissions but I though it helpful to include the entire picture. So there it is. I was thinking possibly the coolant temp sensor or TPS. Well if you have any suggestions please let me know. I would hate to have to get rid of my Z just cause of the stupid emissions laws in CT. My only other thought is sending it to Michigan (my home state) and registering it there. They do not check emissions there. Thanks in advance for any tips you guys can provide. And if anyone can tell me how to use the boost controller that would be greatly appreciated also.

What kind of boost controller is it ?

dont know any z tricks but here is what im sure would help. give the car a good tune up including new fluids plugs ect. this should help but also if you can the best thing to look at is a wideband signal. if your afr's are horrible there is no way you can pass emissions. i passed with flying colors in my subaru catless through the sniffer on a jdm turbo motor running exactly 14.7 at idle (they never reved it up)

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Jesse 73 240z + lq4

Uconn car club president

Its an Apexi AVC-R Boost controller all digital. And the car has had a tune up oil change, air filter and fuel filter. right now the boost is set 0.80 boost and 40% Duty. Its been that way since I got it and I am told that the Duty is the actual amount of boost you get. Is that Right?

Seems to be boosting about 9lbs currently

Actually duty cyle controls the solenoid valve. Basicly helps fine tune your target Boost #
I have mine slightly cut back on the higher Rpms hoping to avoid spike/creep.
Here's the link to the apexi AVCr they have a pdf file you can download with complete instuctions http://www.apexi-usa.com/info/download.asp?id=6115

Thank you I will check it out

Wow...this car has seen a wrench or two! I was wondering about you're ECU. Most people that would go that far with mods might also consider a "hotbox" (modified ECU). Also..."aftermarket" fuel injectors? Just a thought. RDM

Hi Chad,

What number is the vacuum reading on your boost guage at idle?

It is Rich from RDZ, again. I would be happy to check out all the systems. Do a conZult computer check, Power balance test, vacuum/boost test, tune the TPS, Base Test Set, physical check of the engine compartment to see if everything is connected right. Set your boost controller.
ALL 300zx's because of their age should have this done. You won't believe the difference!

Live here in R.I. with a car over 25 years old. My 83 failed emmisions, but still passes the valid inspection. Make shure it's tuned up and running good, do a throttle body cleaning, run some top end cleaner through it, (seafoam, PB blaster has one too which I used,) make shure it's running at the right temp, bad thermostat can fail you. (NOX) add some dry gas to it. Take it out and run the jeebies out of it, (poor mans tune anyone,) and should pass. Here we have 30 days to fix it, and can still legally drive it with the fail paper. So I take there and let them tell me, then I fix what ever.