1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Need Help With Emissions

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Old Oct 25, 2012 | 07:27 PM
  #1  
atheadwins's Avatar
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From: Tucson, AZ
AZ Need Help With Emissions

Arizona Emissions tech ran through all the gears and certainly enjoyed the rotary. But the GSLSE failed:
Hydrocarbons Idle: 1470/220
Load: 539/220
Carbon Monoxide Idle: 6.93/1.20
Load: 6.30/1.20

I am really only posting this because of how badly the car scored.

The car needs new spark plugs, cap, and rotor. I will get those before the next test.

It seems like I need to test the ACV as the numbers were very bad and mine could have been water damaged. Will check the service manual for that info.
Can the ACV be bypassed if it is ruined? The car runs great and I am trying to avoid buying used parts that may not work at all.

Did having fuel system cleaner in the tank screw up results? It has been putting off a little blue smoke since adding cleaner.
Should I try adding a little E85 next test? Don't want to hurt the new engine.

If you have any ideas, suggestions I would love to hear them as the car is a DD and needs to be registered. Tired of printing out temp. registration papers every 3 days lol.

So before the next test I'll replace the plugs, cap, and rotor. I will also get the car nice and warm before testing to try and make the cat happy, along with test the ACV.

If I fail again can I have my cat tested?

If we can't pass legally, we'll do it the hard way. They did a pretty thorough visual inspection after seeing the blue vac lines... Might have to get creative routing air to the exhaust
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Old Oct 25, 2012 | 10:19 PM
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Wish I knew more about SE's. ACV is a logical place to start looking on carb'ed cars, probably for EGI too.
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Old Oct 26, 2012 | 01:21 PM
  #3  
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From: https://www2.mazda.com/en/100th/
yep the ACV is the first step. it needs to be there as it must send the air pump air to what mazda calls "port air", or the exhaust ports. if it doesn't do that it will fail horribly.

you can actually shim the valve so it does port air all the time, but it shouldn't be left this way in normal driving as it'll overheat the cat

the next step would be to check the o2 sensor, it is in use during the test, however your numbers are so bad that its likely to be the ACV. the air pump air has a HUGE impact in emissions
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Old Oct 26, 2012 | 04:38 PM
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From: Tucson, AZ
Originally Posted by j9fd3s
yep the ACV is the first step. it needs to be there as it must send the air pump air to what mazda calls "port air", or the exhaust ports. if it doesn't do that it will fail horribly.

you can actually shim the valve so it does port air all the time, but it shouldn't be left this way in normal driving as it'll overheat the cat

the next step would be to check the o2 sensor, it is in use during the test, however your numbers are so bad that its likely to be the ACV. the air pump air has a HUGE impact in emissions
BIG thanks to DivinDriver and j9fd3s, I think you are spot on about it being the ACV.

Good info on the o2 sensor, mine has seen better days. might be worth replacing.

Is there a thread on shimming the ACV? Either way theres a reputable rotary mechanic in town and I reckon he'll be able to test it in a few minutes and may or may not have a used replacement to bolt on.

Really appreciate the responses and time you both put in sharing the knowledge with everyone. You've helped me without knowing by commenting on tons of threads. Thanks!

Al
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Old Oct 29, 2012 | 12:53 PM
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From: https://www2.mazda.com/en/100th/
Originally Posted by grumpy85
BIG thanks to DivinDriver and j9fd3s, I think you are spot on about it being the ACV.

Good info on the o2 sensor, mine has seen better days. might be worth replacing.

Is there a thread on shimming the ACV? Either way theres a reputable rotary mechanic in town and I reckon he'll be able to test it in a few minutes and may or may not have a used replacement to bolt on.

Really appreciate the responses and time you both put in sharing the knowledge with everyone. You've helped me without knowing by commenting on tons of threads. Thanks!

Al
i've never seen an FAQ on shimming it, but the valve is really simple, there are two diaphragms, one chooses weather the air pump air gets vented or goes into the next valve (relief), and the other switches between "port air" and "split air" (switching). the default is split air and relief so you just shim the valves the other way.
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