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'82 ZXT Epic Smog FAIL! (1042 HC!)


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#1 Connor280ZX

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Posted 30 December 2016 - 01:26 PM

I've been trying to get my ZXT smoggsble for weeks now, but for whatever reason it just runs so damn dirty. Results at idle: HC 1042 Max 192.
Results at 2500 rpm: HC 238 max 168. This is the third test. First test I got 1459 HC which is insane. Replacing the following seemed to help, but the car is still a GP.

 

NO: 1PPM CO: 0.54% CO2: 13.5% O2 3.4%

I've replaced all Vacuum hoses, set timing to 22 BTDC, changed the oil, replaced spark plugs with proper NGK type, ran fuel system cleaner, checked resistance at AFM and CHTS and are within proper resistance, cap and rotor are new and plug wires look new too. New TPS, New o2 sensor, and cleaned electrical connections. Car runs pretty well besides a rough idle and hesitation when cold. Any suggestions? Car was also sitting for 6 years prior.


Edited by Connor280ZX, 30 December 2016 - 02:10 PM.

N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#2 AkRev

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Posted 30 December 2016 - 04:52 PM

Retarding the time lowers HC. What about the catalytic? Those numbers sound like a bad cat, or lack of one to me. 



#3 AkRev

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Posted 30 December 2016 - 04:55 PM

Looking at your post again, the bad idle is a likely cause. When you pulled the spark plugs, was any that had different color than the others? 



#4 blu240z

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Posted 30 December 2016 - 07:45 PM

Always here is right Set timing to 17btdc and put a cat on on it. Been smogging for 20 years

#5 Connor280ZX

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Posted 30 December 2016 - 10:27 PM

It's got a visually good cat on it. No broken/melted cells, and can see right through it. I have not tested before and after exhaust temps yet since I haven't bought an infrared thermometer. 

I cannot retard the timing past 22 BTDC because the "Functional" test will fail if the timing is set further than 2 degrees beyond factory spec. My N/A failed smog once because timing was set at 11 BTDC over 8 BTDC factory. 

 

The spark plugs were all equally dark brownish. 

 

If it matters, the results at 2500 rpm were: 

 

HC = 285 ppm

 

NO = 131 ppm

 

CO = 0.36%

 

CO2 = 13.4%

 

O2 = 1.7%


N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#6 Connor280ZX

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Posted 30 December 2016 - 10:38 PM

Car is also bone stock.


N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#7 FricFrac

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Posted 31 December 2016 - 09:43 AM

Figure out the rough idle - that's likely the root of your problem. Did you go through the FSM? Have you metered out the AFM and CHTS through the harness at the ECU? Rebuilt the AFM?

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#8 blu240z

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Posted 31 December 2016 - 10:37 AM

Timing on turbo cars is 20 + -3 degrees. Can't tell visually if cat is good. You can take emission readings before and after cat.

#9 Connor280ZX

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Posted 31 December 2016 - 12:00 PM

I have done resistance tests per FSM at the sensors themselves, and at the harnesses. Both yielded results in acceptable resistance range. There's a receipt in the glove compartment of a work order to replace the AFM and TPS with new units. This was from 2008. I can assume that the AFM is a rebuilt one. 

 

In that case, I will re adjust timing before next test. I also found that the inspection light from the ECU is not coming on. Not at they key ON position, or at 2000 RPM.


N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#10 Connor280ZX

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Posted 31 December 2016 - 02:16 PM

Swapped ECU's with one from an '83 Turbo. Green light comes on with key on, but still nothing at 2000 rpm. I also can't get the timing under 22, the dist is turned all the way ccw and that's as far down as it'll go.

N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#11 blu240z

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Posted 31 December 2016 - 10:47 PM

Need to set timing up correctly. I think the timing should be at 20 btdc on turbo cars. I had a 280zxt and it wouldn't hold timing at 20 found it had a worn distributor shaft.

#12 Connor280ZX

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Posted 01 January 2017 - 05:25 PM

Are you talking about the teeth being worn? I pulled the oil pump to see if the shaft was lined up correctly (which it was) and the teeth looked fine to me.

N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#13 NewZed

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Posted 01 January 2017 - 05:56 PM

The high O2 and HC indicate a misfiring cylinder.  Gasoilne (HC) and oxygen (O2) are passing through the misfire without catching fire and combining to form CO2 and H2O.  Focus on spark, check valve lash.



#14 blu240z

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Posted 01 January 2017 - 06:21 PM

Yes the shaft does wear, in my case the shaft looked ok but would not keep time. If the timing is correct you should be able to adjust it from 17-23. If you can't retard past 22 you may not have the spindle installed correctly

#15 Connor280ZX

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Posted 02 January 2017 - 04:09 PM

Checked my valve clearances. .007-.009mm cold. Should be. 017mm cold according to the Haynes repair manual. Couldn't adjust them due to the lock it's being way too tight and starting to round off when I turned them. Will have to take it in to get them adjusted.

N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#16 Tony D

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Posted 02 January 2017 - 11:30 PM

Well, you got what I was going to suggest: valve lash.
If those mm numbers are right you were way tight making vacuum go to crap at idle and that will do it!

If you don't get the O2 light, you need to check the o2 sensor wiring as it should start switching after a few seconds at the higher rpm and continue till the sensor cools off.

Edited by Tony D, 02 January 2017 - 11:32 PM.

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#17 Connor280ZX

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Posted 04 January 2017 - 01:05 PM

Got the valves adjusted, and the car idled smoother for sure. There's hardly any fluctuation in the tech needle now. When I got the car, the o2 sensor wire was severed, and I attempted to reconnect it with a splice connector along with a new sensor. There seemed to be two layers of copper inside the wire, and they may be contacting each other with the way I spliced them together. Not sure if that matters though.

N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#18 Connor280ZX

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Posted 04 January 2017 - 04:30 PM

I'm also getting 21 in/hg of vacuum from the manifold.

N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#19 Connor280ZX

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Posted 06 January 2017 - 07:07 PM

Is there anything else besides the CAT temp that I should check before I go back in to smog it?

Edited by Connor280ZX, 06 January 2017 - 07:08 PM.

N/A '82 280ZX   -  '71 240Z (L28, F54/N47) *SOLD*

 

 


#20 Ryan Merrill

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Posted 07 January 2017 - 01:05 PM

Cali must be rough for emissions. Are are strict here but at least cars older than 1987 dont have to be emissions tested. They do have to have all original equipment and Ministry of transportation can pull your car off the road if it fails an inspection






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