1986 CRX HF - Won't Pass Smog HIGH NOX
05-11-2015, 11:33 PM
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Location: Antioch, California, CA, United States
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1986 CRX HF - Won't Pass Smog HIGH NOX
I've looked at the other threads but they were all pretty old
I tried to smog it 3 times. After the first failure with high CO I replaced the air filter, retarded the timing, tried an additive and added octane boost and that made to CO zero but now it had high NO.
The third time was just without additive but still HIGH NOx. What is weird is 1st and 1st smog checks
The SMOG Tech tested the EGR valve and he said it was working, but I dunno, maybe its not flowing enough.
The CAT has only 20k miles.
One thing I noticed is the CO was high but NOx passed on first test, but then 2nd and 3rd test CO was good but NOx was HIGH.
See the photos. The 3 test reports are cut and paste into one image. Top to Bottom (3rd, 2nd and 1st smog test)
http://images.craigslist.org/00T0T_1...lx_600x450.jpg
I tried to smog it 3 times. After the first failure with high CO I replaced the air filter, retarded the timing, tried an additive and added octane boost and that made to CO zero but now it had high NO.
The third time was just without additive but still HIGH NOx. What is weird is 1st and 1st smog checks
The SMOG Tech tested the EGR valve and he said it was working, but I dunno, maybe its not flowing enough.
The CAT has only 20k miles.
One thing I noticed is the CO was high but NOx passed on first test, but then 2nd and 3rd test CO was good but NOx was HIGH.
See the photos. The 3 test reports are cut and paste into one image. Top to Bottom (3rd, 2nd and 1st smog test)
http://images.craigslist.org/00T0T_1...lx_600x450.jpg
05-13-2015, 03:19 PM
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Re: 1986 CRX HF - Won't Pass Smog HIGH NOX
yeah mine does not pass smog all of the time too...
Did you run the car down the highway for a distance before you got it tested so the Cat got real hot? that seems to help me but I am not sure...
I am wondering if i need a O2 sensor
I have a new cat and exhaust
I have reasonably good spark plugs .. recently changed.
Also the last week the engine was running at fast idle of 1000 rpm .. couldnt get it to drop lower after a long drive.. Even messing with the throttle body it still ran fast.. might be the change in temperature and new tank of gas.. i am gonna run it for as long as i can before I take it in to see if it settles down to 700rpm at idle.
I have to get mine smogged real soon like within the next week
I am in the process of changing my Radiator which sucks.
Please reply back if you found the problem.
Did you run the car down the highway for a distance before you got it tested so the Cat got real hot? that seems to help me but I am not sure...
I am wondering if i need a O2 sensor
I have a new cat and exhaust
I have reasonably good spark plugs .. recently changed.
Also the last week the engine was running at fast idle of 1000 rpm .. couldnt get it to drop lower after a long drive.. Even messing with the throttle body it still ran fast.. might be the change in temperature and new tank of gas.. i am gonna run it for as long as i can before I take it in to see if it settles down to 700rpm at idle.
I have to get mine smogged real soon like within the next week
I am in the process of changing my Radiator which sucks.
Please reply back if you found the problem.
05-13-2015, 06:27 PM
#3
Re: 1986 CRX HF - Won't Pass Smog HIGH NOX
high NOx is caused by high combustion temps
Check you cooling system and fuel.
If you don't get enough fuel( fuel helps cool the engine)
High compression(carbon buildup) can also cause it.
Best bet is to check your fuel pressure.(should be 40-45 psi)
Check your engine temp sensor for the ecu
Change the o2 sensor(they get lazy and don't send correct signal for fuel)(also check the wiring for the o2 sensor)
Check your fuel filter.
Check for vacuum and exhaust leaks which can also mess up the readings
Al that said, I bet on the o2 sensor. If possible, get a denso unit, they last longer than the bosch ones
Check you cooling system and fuel.
If you don't get enough fuel( fuel helps cool the engine)
High compression(carbon buildup) can also cause it.
Best bet is to check your fuel pressure.(should be 40-45 psi)
Check your engine temp sensor for the ecu
Change the o2 sensor(they get lazy and don't send correct signal for fuel)(also check the wiring for the o2 sensor)
Check your fuel filter.
Check for vacuum and exhaust leaks which can also mess up the readings
Al that said, I bet on the o2 sensor. If possible, get a denso unit, they last longer than the bosch ones
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