JamesBong

I'm driving an '87 Sport NA. Everything is stock. I just failed smog at idle, but at 2500 RPM, it looks fine. Here's the results.

<table border="0"> <tr> <th>Test </th><th>RPM</th><th>HC Max </th><th>HC Meas </th><th>CO Max </th><th>CO Meas </th><th>RESULTS </th> </tr> <tr> <td>Idle </td><td>767 </td><td>120 </td><td>1103 </td><td>1.00 </td><td>3.58 </td><td>GROSS POLLUTER</td> </tr> <tr> <td>2500 RPM </td><td>2566 </td><td>140 </td><td>47 </td><td>1.00 </td><td>0.03 </td><td>Pass </td> </tr>
</table>
After I failed, I checked my codes and found that the Intake air temperature sensor was disconnected. (Code 15) Worse yet, I did the full tune up with it disconnected, and I forgot to jumper the initial set when I set the idle. It was also about 100° when I got it smoged. Could this be the (only) reason I failed so miserably, or are there other things I should check before I go back.

The car has been sitting about a year because of drive train issues, and lack of time to deal with it. The cats looked fine when they were off AFAIKT.

I really want to fix the problem, not fake the results.

Thanks for the help

Icemark

From the FAQ for FC sticky thread:

so you didn't say what your NOx was, but based on that you either have bad cats, bad O2 sensor, or bad air pump/ACV

JamesBong

Thanks for the reply Icemark.

I've seen that chart, but I wasn't sure what to go after since my numbers are low at 2500 RPM. I'm not too sure that it would be the O2 sensor, because that is in open loop at idle. If it was the cats, wouldn't it fail at 2500 RPM? I'll check the air pump/acv tomorrow.

Oh, for some reason, this station doesn't give results for NOx.

whorider

I would plug in the IAT. Run the air pump dumping straight to the cat. Get a PRE-TEST next and see where it is. With IAT unplugged it will default at like 65 degrees. Way off of your actual temp. Denser air=more fuel=rich run.
I didn't get NOx reading last time either.

Icemark

No, if the cats were bad, the first stage would get warm enough from the high HC, but not the second hence the high CO.... but if we had the NOx we would know for sure, since the 2nd stage in the converter converts the HC to NOx with the air from the air pump.

And is your area a low smog area? Didn't you have to put it on a dyno for smog testing?

I would probably test again, since you know where you screwed up on the tune up. I also would make sure that the oil, spark plugs and air filter are brand new. Make sure the engine temp is up to normal operating temp, before you even start driving to the smog place.

HAILERS

The ACV has a LARGE hose coming out it's outboard side. That hose is long and runs up to the right front fender area where the wiper washer bottle is.

So. Pull that large hose off the ACV. With the engine fully hot, feel the outlet where the hose was. Little air should be coming out. Just a whisper. Then rev the engine over 2500 rpm. The air amount should increase dramaticaly.

IF a LARGE amount of air is coming out that large nipple on the ACV, at IDLE, then it's possible you have the two vacuum hose that control the ACV on backwards. They are just above the ACV itself. Two vacumm hose, both side by side. Pull the aft hose off while at idle. Feel the vacuum coming out of it. Now reach over and pull the BLUE elect plug offf the Relief solenoid. When you do that the vacuum should have stopped coming from that aft hose. If the vacuum did stop, then the two hose are connected to they're right places. If the vacuum did NOT stop when you pulled the BLUE plug off, then I suggest those two vacuum hose are swapped around.

By the way, with a properly set up car, full hot, if you pull the BLUE plug off its solenoid, with everything else connected up right, then when you do that, a LARGE amount of air should start coming out the large port on the ACV where the LARGE hose was connected. That more or less proves the ACV on the whole is working.

Your car does sound like for some reason it's not getting any air to the exhaust ports from the ACV at idle. Converter sounds good since you passed the 25mph (closed loop, 14.7 afr controlled by the ECU).

JamesBong

No dyno testing in the Bay area. (at least not where I went) I live up in the mountains between Los Gatos and Santa Cruz, and it takes me about 20min of windy mountain roads to get to the smog station I'm using, so I'm perty sure that everything is nice and hot when I get there.

I'll be running through the ACV tests in the shop manual tonight and let you know what I found.

Thanks again for the help!

j9fd3s

iTrader: (3)

do what hailers recommends, he knows the system really well.

the idle test is actually harder to pass than the dyno.

JamesBong

OK, so I checked the port on the ACV that leads to the silencer. Lots of air.
I checked the aft vacuum hose; No vacuum, no change when I unplugged the blue Relief solenoid valve. I checked the hoses on the relief solenoid valve, and no vacuum to those. I either have a blocked line, a leak, or a mis-routed hose. Looks like I have more investigation to do. Time to look up the color coded vacuum routing diagram.

HAILERS

Yeah. With a fully HOT engine, both of those two small vacuum hose(located just above the ACV) should have vacuum on them. Removing the Blue plug from the Relief solenoid, closes the path of the vacuum from the Relief solenoid to the aft vacuum line above the ACV.
The other small vacuum line goes to the Switching solenoid and as long as the throttle is at idle, it will be de-energized and allow a path of vacuum to the fwd small hose above the ACV.

And just to make sure............it's the HOSE that should have vacuum on it. Talking the two small vacuum hose above the ACV. NOT the metal nipple the hoses connect to. Just making sure.

Look at the solenoid with the Blue connector and then at the solenoid with the Grey connector. Notice how the FILTER on them is in a different place when you look at one then the other???? That is why when one solenoid (Blue) is energized it will pass vacuum and at the same time when the other solenoid(Grey) is de-energized will NOT pass vacuum.

All the solenoids are the same outfits, but whay they (Mazda) do, is rearrange where the filter is. You can pull the filter off and put them on any of the nipples on the solenoids. I suggest you also look in the FSM, FUEL AND EMISSIONS, and look at the Relief and Switching solenoids in the manual. See if the FILTER for a given solenoid, looks like it's in the same place on YOUR solenoids, as in the manual.


No vacuum on BOTH seems to indicate you have the three vacuum lines on the front of the dynamic chamber connected wrong. One hose is LARGE so you cannot get that one wrong. So it might be that the other two are crossed. I forget right now which goes to the vacuum rack and which goes to the fuel injector air bleed nipple under the dynamic chamber. If you can't figure out which is which I'll take a look tomorrow.

Usually if you cross the two small vacuum lines on the front of the dynamic chamber, the idle will be crummy due to one of the two small lines NOT being a source of vacuum and the other being a vacuum source. The NON vacuum line goes to the fuel injector air bleed nipple b/t the two oil injectors under the dynamic chamber. That nipple gets filered air, NOT vacuum. Something like that.

I'd say about 20* of the above makes sense. humor

I'm also assuming that this is what you say it is. A non turbo 1987 RX-7.

And while I'm here, the air blowing out the side of the ACV where the hose to the silencer connects means...............that there is NO air going to the exhaust ports where it's needed. Instead its going to the silencer in the fender, doing nobody any good.

Your passing the 25mph test because the 02 is going into closed loop and the ECU is putting out a 14.7afr. No extra air needed from the airpump for that. Normal operation. Gone.

JamesBong

Ding Ding Ding. You are correct! The two small hoses on the front of the dynamic chamber were swapped. I just figured that out before you posted. The sad thing is that I paint marked one hose, and next to it's corresponding nipple so I wouldn't get them mixed up! (duh!) Now the exhaust smells more like steam than gasoline. YAY! My commute tomorrow will tell me if there's any other problems.

Thanks!

JamesBong

I finally got the seven smoged yesterday, and it passed with flying colors! Amazing what correct vacuum routing will do!

<table border="0"> <tbody><tr> <th align="left">Test </th><th align="center"> RPM
</th><th>HC Max
</th><th>HC Meas
</th><th>CO Max
</th><th>CO Meas
</th><th>RESULTS </th> </tr> <tr> <td align="left">Idle </td><td align="center">767 </td><td align="center">120 </td><td align="center">11 </td><td align="center">1.00 </td><td align="center">0.00 </td><td align="center">Pass</td> </tr> <tr> <td align="left">2500 RPM
</td><td align="center">2566
</td><td align="center">140 </td><td align="center">8 </td><td align="center">1.00 </td><td align="center">0.00 </td><td align="center">Pass </td> </tr></tbody></table>
Not bad for an engine with almost 160k on it!
Thanks again for the help!