# emissions problems 87 300zx



## 300zxgirl (Sep 24, 2004)

Hi, I have an 87 300zx N/T and I have some emissions problems. I pre-tested ( I had a feeling it would fail) it pre-tested as a gross polluter(I live in CA.) the HC failed at idle max is 112, it measured at 248. NO failed also at idle, max is 778 it measured at 2392. At 25 MPH everything passed. I changed gas cap, and did spark plugs, wires, rotor and cap. I haven't taken it back to test yet, I was wondering if anyone has any other suggestions that may help. I LOVE my car, and wanna get it back on the road, I miss driving it, it's been sitting in my driveway for 4 months.... ANY help would be greatly appreciated!
THNX...


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## ♣300zx♣ (Aug 6, 2004)

300zxgirl said:


> Hi, I have an 87 300zx N/T and I have some emissions problems. I pre-tested ( I had a feeling it would fail) it pre-tested as a gross polluter(I live in CA.) the HC failed at idle max is 112, it measured at 248. NO failed also at idle, max is 778 it measured at 2392. At 25 MPH everything passed. I changed gas cap, and did spark plugs, wires, rotor and cap. I haven't taken it back to test yet, I was wondering if anyone has any other suggestions that may help. I LOVE my car, and wanna get it back on the road, I miss driving it, it's been sitting in my driveway for 4 months.... ANY help would be greatly appreciated!
> THNX...


Possible o'2 sensor, Causing it to run to rich.... hows your MPG?


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## 300zxgirl (Sep 24, 2004)

♣300zx♣ said:


> Possible o'2 sensor, Causing it to run to rich.... hows your MPG?




If I remember correctly, I get about 225 miles per tank(city driving)


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## ♣300zx♣ (Aug 6, 2004)

300zxgirl said:


> If I remember correctly, I get about 225 miles per tank(city driving)


Sounds about right...If you fail to HC, that means you have to much unburned fuel... @ idle your just fine, right? The O's sensor tells the fuel computer how much fuel to send the injectors. o's are fairly cheap about 80 bucks or so. And it will increase your MPG. :cheers:


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## 300zxgirl (Sep 24, 2004)

♣300zx♣ said:


> Sounds about right...If you fail to HC, that means you have to much unburned fuel... @ idle your just fine, right? The O's sensor tells the fuel computer how much fuel to send the injectors. o's are fairly cheap about 80 bucks or so. And it will increase your MPG. :cheers:



at 15mph it failed at 25mph it was ok... I'll try the O2 sensor THNX


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## Nismo Skyline (May 2, 2002)

300zxgirl said:


> at 15mph it failed at 25mph it was ok... I'll try the O2 sensor THNX


You must do a few other things to make it pass in cali.

1. Change the engine oil and filter. Fresh oil will reduce the HC's a lot compared to old oil.
2. New spark plugs, NGK heat range 5 which is hotter which helps at low speed.
3. Take it on the freeway before you go test it and run it in 3rd gear at 3000 rpm for a minute or two to clean out the combustion chambers.

Since it is passing at 25 mph, that means it not too far out. Until the cat warms up, it's running rich.


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