2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Failed Emissions S5 na

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Old Mar 27, 2015 | 05:53 PM
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Failed Emissions S5 na

My FC failed emissions since I need to set the timing, tps makes the idle bounce around, and probably because the air pump doesn't have a belt on it (adjuster bolt snapped). I put on a cat/resonator that I used last emissions test and have only used it for the tests so the cat isn't bad. Would the timing off and air pump not working properly give that high of a reading or is there other things that I should be aware of that could also be in play?

Failed Emissions S5 na-fc-emissions.jpg
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Old Mar 27, 2015 | 06:02 PM
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A properly functioning air pump is vital to passing emissions on these cars make sure its hooked up and your air control valve is properly diverting the air.
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Old Mar 27, 2015 | 06:18 PM
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Failed emissions without a working air pump? You don't say...
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Old Mar 27, 2015 | 06:35 PM
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The problem I have with the air pump is that the bolt is snapped to tighten the belt so I took off the belt. The pump is still on though. I don't know if there's anything else I could use to tighten it in place so I could have the belt back on to run it.
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Old Mar 27, 2015 | 09:11 PM
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it needs the air pump. then set the idle speed, bouncing is probably bad.

then it should pass, 220hc's is pretty generous
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Old Mar 28, 2015 | 09:43 AM
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Your HC and CO are too high (no NOx reading?). High HC means incomplete burn, CO is the same. Because of the design of the rotor housings, some fuel from a charging chamber is able to make its way to the end of the power chamber/beginning of the exhaust chamber, and it makes for a pretty dirty burn. The air pump injects fresh oxygen into the still fairly charged exhaust gases and gives the unburnt hydrocarbons something to chemically react with using the heat of the exhaust gasses already present. In a nutshell, this is what the air pump does.

Mine is adjusted differently than yours it sounds like, but my AC compressor has an adjustment bolt. When I changed the belt last weekend, I discovered the PO bent it somehow, so naturally it simply snapped when I attempted to loosen it. I simply pulled it out and went to my favorite hardware store (McGuckins!) and got a new one. The new one was shouldered for the majority of its length, but I have a pretty comprehensive collection of taps and dies, and was able to make short work of it. If memory serves, you're looking for an M6X1.0 X 90mm bolt (naturally, assuming it's the same).

That will go a long way, but getting the rest of your house in order will probably also prove necessary. A basic tuneup should be done once a year at a minimum.
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Old Apr 3, 2015 | 06:08 AM
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Originally Posted by Kenshin XI
The problem I have with the air pump is that the bolt is snapped to tighten the belt so I took off the belt. The pump is still on though. I don't know if there's anything else I could use to tighten it in place so I could have the belt back on to run it.
Take the pump off and drill through the old broken off one.Then put a small "through bolt" in the hole.
Then put the belt back on.
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Old Apr 3, 2015 | 11:32 AM
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Originally Posted by spectre6000
Your HC and CO are too high (no NOx reading?). High HC means incomplete burn, CO is the same. Because of the design of the rotor housings, some fuel from a charging chamber is able to make its way to the end of the power chamber/beginning of the exhaust chamber, and it makes for a pretty dirty burn. The air pump injects fresh oxygen into the still fairly charged exhaust gases and gives the unburnt hydrocarbons something to chemically react with using the heat of the exhaust gasses already present. In a nutshell, this is what the air pump does.
in a nutshell, rotaries don't burn fuel very efficiently! haha. no dwell. no time for atomization. just get it in and get it out! and without a working airpump that cat will surely fail in short order as well. so get on it quick!
i don't believe vehicles of an era equipped with only 2-way cats were required to meet NOx emissions standards. that would make sense to me anyways
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Old Apr 7, 2015 | 08:17 PM
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I was considering taking my air pump off. Can anyone tell me the pros and cons of doing so i have a inspection so im good to go as far as that goes. Any help is appreciated. Thanks
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Old Apr 7, 2015 | 10:50 PM
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most people remove it after installing an aftermarket exhaust, since the new exhaust typically won't have the provision for split air which the air pump provides. nor will many run a catalyst to make use of the air pump if it did. it also opens up space in the bay to make work easier. and reduces drag on the engine i suppose
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Old Apr 7, 2015 | 11:08 PM
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His S5 has no need of exhaust pressure, the airpump powers his 5th/6th ports.
Remove the pump and you lose function of those ports.
People seem to like wiring them open but report a loss of bottom end after doing so.
Or you could use an electric airpump.
I've worked with older Corvette airpumps and they seem robust enough but are about the same size as the stock Mazda part, so I don't think you gain much from a packaging perspective.
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Old Apr 7, 2015 | 11:13 PM
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ohhh yea. the actuators. i honestly doubt you lose much, if any, in the lower range with them open. my old s5 6port were open and that thing seriously screamed. stock ecm and injectors too
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Old Apr 7, 2015 | 11:18 PM
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i haven't driven a 6port with working actuators though to base a comparison. but this thing was pulling against my t2 though
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Old Apr 7, 2015 | 11:22 PM
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Regardless of the consequences, I just thought he should know.
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Old Apr 7, 2015 | 11:25 PM
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nope. be quiet. he need not
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Old Apr 8, 2015 | 12:28 AM
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I haven't driven with the 5/6 port actuators disabled/wired open, but I'm fairly certain that Mazda wouldn't have gone to the considerable expense and complication they add if they didn't deliver real benefit. NAs have little enough torque as it is, so unless the car is intended primarily for track use, or one is fine with keeping the revs high all the time, the loss of lower rpm torque is likely to be noticeable. It's the rotary equivalent of variable valve timing and lift in a piston engine.
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Old Apr 8, 2015 | 12:36 AM
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mmmm not quite. they're secondary ports. like secondary ports in a piston engine. all i ever hear about disabling them is people who say just what you said. speculation. mazdas primary goal is not always what produces optimal hp or torque values
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Old Apr 8, 2015 | 01:00 AM
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In the case of the 5/6 ports, the goal specifically is, however, to deliver better breathing capacity at higher rpms, without having the engine fall flat on its face at lower rpms due to low intake velocity, and the poor chamber-filling and low torque that go with. Secondary ports is a better analogy, though.
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Old Apr 8, 2015 | 01:59 AM
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i get what you're saying. in theory, nothing but negative effects should be seen by keeping them open. which is why i can't explain why, but my old 6port s5 just sang like a canary, all through the band.
deleted actuators. exhaust. 12lb flywheel. cone filter. and a t2 trans. that's all. mazda reman, so i can't see any port work being done to that
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Old Apr 8, 2015 | 06:59 AM
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Originally Posted by welfare
i haven't driven a 6port with working actuators though to base a comparison.
Originally Posted by welfare
i in theory, nothing but negative effects should be seen by keeping them open. which is why i can't explain why, but my old 6port s5 just sang like a canary, all through the band.
Maybe with working actuators it would have screamed like a banshee instead of warbling like a songbird.
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Old Apr 8, 2015 | 08:42 AM
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you may very well be right. unfortunately the car was like that when i'd bought it, so i couldn't compare with and then without.
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Old Apr 8, 2015 | 08:44 AM
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it was, however, far from warbling.
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Old Apr 8, 2015 | 08:48 AM
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I read on aaroncake that its a loss of 25hp above 4000 rpm. TThere is an easy way to check Them so i guess ill check to see if they work. if they dont work ill open them up till i can fix them to see if theres any real difference. My inital interest came from these rb headers i have which have the pick up tube for the actuator And i wasnt sure if the airpump had anything to do with the actuators. Thabks for the help everyone.
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