1982 Nissan 280Z 280zx starts up fine runs amazingly. But fa

Tiny
KRIMSYKRIM
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  • 1982 NISSAN 280Z
Engine Mechanical problem
1982 Nissan 280Z 6 cyl Two Wheel Drive Manual xxxxxx miles

original results were Hc 6.43 (passable is 3) Co 99.61 (passable 25) and nox.72 (passable 3.5). So I replaced the cat with a california cat, all spark plugs (the ones I took out were gapped.2 instead of.45) changed all plug wires, distributor cap and rotor, upgraded the stock filter (can not find stock filters for it) with a spectre performance filter (largest and most breathable filter available) and kept it in the stock spot, and poured in a little NoS fuel addative that cleans the system out and lowers HC and CO readings. Took it back, drove it around for a few minuets (maybe 15) to warm it up, took it in at running temp (dead center on the temp gauge) and it failed with HC 6.24 CO 124.45 and blew nox away with.07. I used the Napa head/gasket test for the radiator. Blue-> yellow= leaking had/gasket. Mine turned green. Noticed the radiator fluid had been sucked up to the bottom of the tester so I retsted it and got the same results, but again had radiator fluid sucked up to the tester. The exost does not smell of radiator fluid, I have no error codes when I press the computer button on the dash and no idiot lights, and the oil looks and smells clean with no bubbles. Also did a compression test- 5/6 cylinders are at 160-170 and one was 140-150 (from what I read they should be 160+/-5%) My on dash oil pressure gauge sits at about 50psi at idle but varies up to i'd say about 60. With the car out of gear revving up to 3k rpm the oil pressure goes to 60-70 and the cap is around 100. The vehicle drives great, has no lack of power or pickup in speed, does not sputter at low or high rpm, and has no problem going up to and past 5k rpm As suggested by the emissions tester I tried to take it to a mechanic shop but I was just told the vehicle is too old and they cannot do anything with it. Misc other things I have done are replace the radiator with a factory new radiator and replace the fuel cap with a junkyard cap (was sold to me without one and new parts are very difficult to find)
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Monday, October 18th, 2010 AT 5:07 PM

16 Replies

Tiny
MERLIN2021
  • EXPERT
Oil change will lower HC readings, but in your case I don't know if it's enough, O2 sensor may be a bit out of wack, did you repace that? And last, on your low cylinder, re test using a few drops of oil in the cylinder(into the spark plug hole) and see if the reading comes up, if it does the rings are worn, if not the valves are leaking. Any Blue smoke from the tailpipe? You can try some smoke away oil additive, this will coat the cyliders and thicken the oil a bit, it may sneak you past an inspection if oil burning is your problem.
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Monday, October 18th, 2010 AT 11:10 PM
Tiny
KRIMSYKRIM
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I did not replace the o2 sensor, I was going to but I was told by the mechanic at autozone that 1) they had no way of testing my sensor and 2) that I would get an error code if it went bad. So I did not replace it mostly based on no error codes. I have no smoke at all coming from my tailpipe that I have noticed and I never smell it burning any oil. The only time I've seen it smoke is when I fired it up after using the NoS additive I assume that was a result of it cleaning out the gunk in my engine because it stopped after it warmed up a little. I'm very. Cautious about replacing parts on the car with anything off the shelf because it is becoming a recurring problem that the parts I am sold are not the correct parts for the vehicle even if the stores computer system says it is the correct part. Would an incompatible sensor cause this problem? Knowing there are discrepancies in on shelf parts to on the car parts and the person who had the car had so little knowledge of the vehicle that he put.22 gap plugs on a.45 gap engine I would also wonder if the o2 sensor or oil sender unit were replaced with mismatched parts. I will retest the low cylinder tomorrow and if oil raises compression I will try the stop smoke
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Tuesday, October 19th, 2010 AT 4:46 AM
Tiny
MERLIN2021
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First O2 sensors on your car are recommended for changes, every 50,000 miles. And no it can be out of range enough to cause it to run rich, and NOT set a code. Replace the sensor.
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Tuesday, October 19th, 2010 AT 10:39 PM
Tiny
KRIMSYKRIM
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I picked up an aftermarket 02 censor this morning with the misgapped plugs and all the fuel going out my tailpipe it would make sense that the sensor is gone altogether and the ecu's only backup plan is too much gas is > not enough. Hopefully this works
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Tuesday, October 19th, 2010 AT 10:59 PM
Tiny
MERLIN2021
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You might also want to clear the memory by removing the negative battery cable for 5-10 minutes, then drive for about 100 miles before reteseting the emmissions.
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Tuesday, October 19th, 2010 AT 11:07 PM
Tiny
KRIMSYKRIM
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I am unable to drive the vehicle pretty much at all. I bought the car about a month ago and the last owner used the 30 day and the 3 day temporary tags. (He did no work to it from what I can tell other then maybe plugs, just used the tags to drive it) I have about 10 months for the 30 day and 9 on the 3 day tag. The vehicle is currently unregistered with no plates untill I can pass it through emission. I've been towing it to the emissions tests and running it on side roads around the testing facility to warm it up.
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Wednesday, October 20th, 2010 AT 4:35 AM
Tiny
MERLIN2021
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Well I don't know about RMV laws and registration, in Mass where I live, your are registered or not, NO temp plates here.
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Thursday, October 21st, 2010 AT 11:21 AM
Tiny
KRIMSYKRIM
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That is interesting, in arizona if the vehicle can not pass emissions you get no registration and no plates (illegal to drive without both of them) but you are allowed 3 ways to repair your car. 1) a 3 day restricted use tag to drive it to repair shops etc 2) a 30 day temporary tag to repair and get the vehicle running correctly and 3) a one time per vehicle one year exemption from emissions if you meet a certain $ amount in repairs and have under 2x the allowable level of emissions. I can not benefit from any of the 3 since my cars emissions are 5x the standard and the previous owner used both temporary tags
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Thursday, October 21st, 2010 AT 7:57 PM
Tiny
MERLIN2021
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Did you finish with the compression test? New O2 sensor?
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Saturday, October 23rd, 2010 AT 12:02 PM
Tiny
KRIMSYKRIM
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I did install the 02 sensor the old one does look blackened and used but I'd assume that is normal for an 02 sensor. I have not had a chance to retest through emissions or do another compression test yet.I'm relearning why I do all my own work from firestone. My break problem diagnosed and fixed by my cousin in a day. My girlfriends- misdiagnosed 5 times, our driving abilities questioned, 1,000$ in parts that may or may not have been bad.4 days of wasted time. And the car is in worse condition then when we took it in =P. I'll reply as soon as I have time to do something to my 280 but if this doesn't do it I may seek 'professional' help from a family mechanic.
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Monday, October 25th, 2010 AT 4:50 AM
Tiny
KRIMSYKRIM
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My cousin is helping me out. Replaced the pcv valve, fixed a minor timing problem, and looking into a valve/lifter tapping. Going to throw a compression test in there with it. As always, your site's advice is greatly appreciated but expert eyes and ears help =P
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Tuesday, October 26th, 2010 AT 5:19 PM
Tiny
MERLIN2021
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I agree! Let me know how it goes.
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Tuesday, November 2nd, 2010 AT 10:30 PM
Tiny
KRIMSYKRIM
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Still failed.I had a prblem with my advance timing so when he retimed it correctly, it ended up not running at all (sad when they have to push your car out the door because it cant clear the 1 inch lip on the dyno). So he re re timed it, redid some vacuum lines that were not hooked up correctly, got it running again and did what he could for my advanced timing (vacuum problem) and. It still failed. Thanks for your help but I think there are too many problems to diagnose
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Thursday, November 4th, 2010 AT 6:24 PM
Tiny
MERLIN2021
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Well you did say you had a low compression cylinder, weak engines will not have good vacuum, this may contribute to your timing issue, Have you wet tested the low cylinder as I suggested? It sounds like the engine needs some mechanical work.
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Saturday, November 6th, 2010 AT 9:26 AM
Tiny
KRIMSYKRIM
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The vacuum problems went away when we redid all of the lines, things were not hooked up or hooked up in the wrong place, etc. The vehicle is running again, and it has power again, but still failed emissions horribly. Nearly out of things to check but the injectors and the fuel system, things seem to be pointing towards an injector problem. However, problem solved. I am moving to Missouri and they have no emissions standards so I can drive the car and find out the problems the right way driving it.
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Tuesday, November 9th, 2010 AT 10:25 PM
Tiny
MERLIN2021
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Good luck with it. If you re do the compression test and find one cylinder low, it will cause unburned or incomplete burn to run thru the exhaust.
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Thursday, November 11th, 2010 AT 9:02 AM

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