Failed Emissions - High Hydrocarbons Under Load
 

Anyone want to trade 50HC for 1200NOx?

https://www.rx7club.com/attachment.p...1&d=1210021449

I can't figure out what the problem is...

All of the following are less than one year old:
-Cat (Bonez)
-O2 sensor
-Plug wires (NGK)
-Air filter
-Both fuel filters
-Battery

Plugs are brand new (NGK).
Oil was just changed.
TPS was checked and rechecked before the test, it's right on.
Idle adjusted to 900rpm.
Timing properly adjusted.
I can't find any vac leaks.
Both rotors test at 90psi.
I drove the car quite hard before testing, I don't think I could get the cat any hotter.

Any ideas?

not bad. i failed. here its 114 allowable, mine was 997 ppm.

peace

Air pump working?

Test the emissions solenoids (relief, switching, port air, split air) to be sure they're working.

http://mazdarx7.iougs.com/emissions.shtml

My first instict is air pump as well. However, RR88 just gave you a gold mine.

you also have to check the air control valve to make sure its actually good, and the vacuum hose routing, the solenoids always work

Oh man there's a lot of stuff to check.

I checked the air pump itself and it definitely puts out a lot of air. I was trying to go through the FSM section on the secondary air injection system but I gave up when I couldn't even figure out if the check valves are working.

It feels like hot air (maybe exhaust?) is coming out of the air control valve inlet when I disconnect the hose from the air pump. Would this indicate a bad check valve in the intake manifold, or is this normal? Do the check valves fail often?

Also, how much air should come out of the ACV outlet (to air silencer)? I couldn't really notice anything even at 2500rpm.

I guess I'll go through all of the info you guys have given me tomorrow.

Make sure your timing is set correctly if it isn't. Do a search here for "timing", theres a few good threads with pics of the CAS and how it should look when the yellow tick is lined up.

If not, the easiest way is to get a new cat.
With a new cat you'll pass no problem.
Also if the cats on the car have never been replaced, definately get a new cat.
New cat= easy way to pass.

Timing is set to factory specs.
Cat is 9 months old.
Thanks anyway.

Also, how much air should come out of the ACV outlet (to air silencer)? I couldn't really notice anything even at 2500rpm.****************************************** ************************************************** *********************************
That on the whole sounds good. It should not dump air until you hit around 3800 rpm (much like suggested by the FSM). So, with a hot engine, rev it to over 3800 rpm and see if it dumps the air from the ACV. IF it does, that's normal. Talking reving in the driveway, not driving.

But it SOUNDS like your airpump is working because at idle you have no problem. It SOUNDS like the airpump is dumping when the guy *drives* the car. Therefore the air isn't going to the exhaust ports. Not good.

You have the two vacuum hose from the relief and switching solenoids crossed???????? Maybe? They connect just above the ACV itself. You didn't say what car. Turbo/non turbo/series four/series five.

Pull that ACV off (just three nuts) and see if the spoked check valve is any good or even there. Never hurt to look.

If it's a NON TURBO, idle the engine HOT. Pull the BLUE connector off the Relief solenoid. Air should now exit the large nipple that feeds the silencer in the right front fender. If not, then maybe you do have the two vacuum hose above the ACV crossed or something is wrong with?????

Split air and Port air solenoids have zippity to do with your problem. The split air solenoid only opens when in fifth gear, something the emissions guy isn't going to obtain, and the Port air ..........well, it just ain't your problem. Go drive your car with a LED light connected to the Port Air solenoid wires and watch it. Nope, ain't the Port air solenoid.

The ACV is controlled by the Switching and Relief solenoids. Plus the TPS in turn determines if those two are working right (look at your wiring diagrams and the TPS Check connector. Look at how there are two wires spliced into two of the TPS Check connectors wires. Those two spliced wires go to........the Relief and Switching solenoids. When the TPS is set right, it outputs one volt dc to the ECU which in turn energizes the Relief solenoid. When the Relief solenoid is energized it ports air to the ACV's relief solenoid (NON TURBO ENGINE not talking TURBO ACV). Just my way of saying to make sure the TPS is set right.

I'm also saying, even though your rev to 2500 rpm and feel no air coming out the Relief nipple to the silencer, when the car is actually driven, that may not be the case. Things change when the car is in gear and actually moving and the ECU sees the pressure sensors output change. (made Part of that up out of whole cloth).

That's as far as I care to go with this. Tired of emissions threads.

It's an S4 NA.

This is why I thought it should be dumping at 2500rpm:
https://www.rx7club.com/attachment.p...1&d=1210055922

After doing some more research I'm only increasingly confused. I'm sure you're right about driving under load vs. reving in the driveway.

It's entirely possible that the lines are crossed, I'll check that tomorrow. When I was attempting to follow the FSM testing procedures every time it said "check that air flows out" it was doing the opposite. So I figured I was doing something wrong and gave up.

I'm planning to pull the ACV but figured I would wait until I had a new gasket in hand, since I'm still daily driving the car. Or should I just pull it off anyway?

This post was very helpful, I feel as though I have a better understanding of the system now. I hope you're right about the relief/switching vac lines. That would be a simple fix.

Thanks.

Do the alcohol trick. it took my hydrocarbons down about 90ppm which would help you pass.

[QUOTE=MazDan;8164269]It's an S4 NA.

This is why I thought it should be dumping at 2500rpm:
https://www.rx7club.com/attachment.p...1&d=1210055922

After doing some more research I'm only increasingly confused. I'm sure you're right about driving under load vs. reving in the driveway.***************************************** ************************************************** ***************************
Your picture out of the FSM makes me say I was wrong. Sorta.

I'm used to doing what the FSM says a couple of pages after that. The paragraph called Relief Solenoid Valve Inspection Signal. It's the part about half way thru that paragraph where you have the vacuum hose off the Relief Solenoid that runs b/t the Relief solenoid and the ACV. Then rev the engine to 3,400 to 3,600 rpm and when you do that rpm, no air is sucked into that hose (at the Relief solenoid).

I sort of bypass the part about pulling the hose off the Relief solenoid that runs b/t the Relief solenoid and the ACV. It's easier to pull that same hose off just above the ACV itself than pull it off the Relief solenoid. It's more out in the open.

It also helps to know that when the Relief solenoid loses power/gnd, it no longer ports vacuum to the ACV, and when that happens, a diaphram relaxes in the ACV and dumps air over board to the silencer. So. Knowing that, I don't disconnect the hose at the Relief solenoid nor at the ACV. I just rev the engine to 3800 rpms and if air starts blowing out the ACV into the silencer in the right front fender, then I basically know that the thing is working.

The engine has to be up to temperature for some of this to work. On a 86-87 there is a water temperature switch on the bottoom of the radiators left bottom side and it will de-engergize the Relief solenod when the water is cold, and air will come out the ACV to the silencer all the time til the water temp comes up to ????? I think the figure is around 90*F or so. This is NOT your problem though.

If you look at that diagram of the internals of the ACV at the beginning of that Secondary Air Injection System, you can see how, if you have a vacuum on the RELIEF valves diaphragm, the poppet on that valve will close off the passage to the silencer so air cannot escape to the silencer from the ACV. So, keeping that in mind, and knowing that the Relief solenoid only ports vacuum when energized, that if you pull the BLUE connector off the Relief solenoid, then the relief poppet in the ACV relaxes and air can escape out to the silencer. So, sometimes I just pull that Blue plug off while at the same time feeling the amount of air coming out the large nipple on the ACV to the silencer. When the blue plug is disconnected you'll feel that air amout coming out the ACV increase quite a bit. Even at idle you should be able to feel the difference.

When that happens I pretty much know that I have the routing of the two hoses right and the ACV is working to some extent anyway.

That is for a NON TURBO engine. Turbo's work a bit different.

I'd also recommend doing what the FSM says in that Relief valve checkout. The part where you pull the TPS connector apart while feeling if air/vacuum is coming from the relief solenoid to the ACV and what happens 120 seconds later.

That lack of vacuum/air after 120 seconds happens *in real life* so to speak. After driving for over 120 seconds the Relief solenoid gets de-energized and air from the air pump is sent overboard to the silencer (if it's going there, it ain't going to the exhaust ports anymore). The Relief and Switching solenoids always have 12vdv on them, it's the ground that makes the energize or de-energize. Gnd comes from the ECU and triggered by the TPS signal to the ECU. That's why a properly rigged TPS is more or less important.

Go to CONTROL UNIT in the FSM where it shows the input/output of each pin. Look at the TPS output, pin 2G where is says "approx one volt" TPS adjusted properly.

That said, I need to go back and follow the FSM instead of using memory. But I think you can see where some short cuts can be taken to see if a ACV is working or not.

The spoked check valve should keep exhaust gas from coming out towards the airpump. But frankly I don't ever remember acutally doing that myself (to much pain pulling the hose off b/t the airpump/ACV.

And by the way, the part where they have you check the airflow coming out the split air pipe by pulling the vauum hose off the switching solenoid.............don't look for much air flow. It isn't a dramatic amount. Nothing like the air coming out the side of the ACV to the silencer when the relief solenoid is de-energized. In fact at one time in life I actually ran the outlet of the split air pipe into a pail of water and looked at the bubbles at idle, then pulled the vacuum hose off that goes b/t the switching solenoid and ACV and watched the increase of bubbles. About all I can say..........the bubbles did increase in volume. That checkout sucks.

Oh. By the way, remember the part about the 120 seconds and air goes to the silencer????? That's why the 02 sensor needs to be working with the ECU. At idle the 02 sensor is not in closed loop,. Has no effect on anything at idle. But when driving, and after 120seconds or so, then the 02 being in closed loop counts a lot, because it is now trying the maintain a 14.7afr to clean up emissions.

That 120 seconds can be misleading. It's true that air will dump after 120 seconds, but if your doing normal city driving and come to a stop and go again, then it's another 120seconds again before it dumps air again. Something like that.

Yeah, your right about the 1500-2500 rpm.

By the way. Those two hose that are directly above the ACV on a series four non turbo. The rear one is from the Relief solenoid and the fwd one is from the Switching solenoid. Both should be pulling vacuum at idle.

Pull the rear one off and feel the vacuum on the Hose. At the same time pull the blue connector off the Relief solenoid. The vacuum should stop when you do that.

The switching pulls vacuum at idle also, but is de engergized so pulling it's plug off will have no effect at all at idle.

Anyway, the above will tell you if you have them swapped or not. It's easy to get 'em swapped accidently.

I've a 86non turbo car and I took that hose off b/t the airpump and ACV. I put a old piece of hose on the ACV side of that hose where the hose end would be away from the air coming out of the airpump and cooling fan. When at idle I can put my thumb over the hose and although I don't feel air coming out, I do feel a slight plusation of some sort. If I rev the engine the pulsation goes away and there is definetly no air coming out of the ACV back toward the airpump.

That check valve is just a flat piece of metal and on the engine side of it is a piece of rubber covering the spoked area. A spring holds the rubber in place and keeps exhaust air from the exhaust ports from coming back to the airpump. When the airpump is working, its pressure pushes against the piece of rubber and overcome the spring force and lets air pump air go to the exhaust ports. Something like that.

If you bust the ACV 's gasket, just buy some gasket paper at the store and make one for yourself using an exacto knife and marker.

i know what you mean, the efi cars pass in ca no problem, and ALL you need to have is a working air pump/acv and cat.

it helps if everything else is good, but you dont need it.

I did this quick test today, looks like the lines were properly hooked up. I guess my next step will be to rip the ACV off. I didn't even think about making my own gasket, good tip. I'll do that later on today and report back.

Alcohol trick is plan B. But if you fail an emissions test here you can still buy 3 months conditional insurance, so I have a while to figure out the problem. I would much rather just fix the problem so I don't have to go through this again. I wonder if that's how the previous owner got it through?

Well I pulled the ACV off, it was much easier than anticipated and the gasket stayed in one piece. Judging by the differential of carbon buildup on either side of the check valve I'd say it's working. There was a lot of carbon on the intake side so I didn't want to try blowing through it.
There was a small amount of carbon on the ACV side though. Since I already have a new check valve coming I'll swap it later anyway.

I suspect there may be something wrong with the split air pipe check valve. it feels like there's as much hot air coming out of it as there is fresh air going in. Maybe I'll pick up a new pipe. My theory is that since not much air ever really gets sent to the split air pipe, it's possible that some escaping exhaust is bypassing the check valve and is creating enough backpressure to prevent the pumped air from reaching the cat. Does this make any sense?

After I put the ACV back I did all of the relief and split valve tests in the FSM and they all seemed to check out. The only thing I'm unsure about is the relief valve.
After waiting the 120s it stopped sucking just like the FSM claimed, but when I let it drop back to idle speed (with the TPS still unplugged), it didn't seem to be sucking again. I waited much longer than the specified 8s (step 6, pg4A-44). Does it only suck for 8s, then stop again?

This is a lot more frustrating than I was expecting. I figured I'd find some missing parts or swapped hoses and it would be a simple fix.

Thanks again to everyone who's been helping. Especially Hailers.

I've seen 'em with quite a bit of carbon on the intake side. You should be able to just clean the excess carbon off with???? PB Blaster or the equiv or just plain gasoline.

After 8 seconds I'm pretty sure it should have kept sucking. I'll check it out in the morning. Late morning.

Have you ever backprobed your 02 sensors wire at the ECU and checked to see if it's inputting to the ECU. It reads b/t zero volts dc and one volt. At idle and with a hot engine and airpump/acv working, the reading will be very low. Waaay low.

But if you just reach over and pull the BLUE plug off the Relief solenoid, the figure will go to the 0.7 or 0.8 vdc range........because now the air pump air is going to the silencer instead of the exhaust port.

The very LOW reading at the beginning was BECAUSE airpump air was going to the exhaust ports which are located before the 02 sensors location.

Checking the voltage reading of the 02 sensor as described above gives some indication if the system is working right. Just my opinion. Not written anywhere else saying so.

Interesting, I guess that's all an A/F gauge does, but with LEDs. That's a good idea, I'll try probing the ECU tomorrow.

Well, IF you have a AF gauge, use it instead. Same results.

the wideband on my otherwise stock s5's show 17-18:1 under 1500rpms. after that it should be switching @14.7:1

OK here are the results from the O2 probe. (No this car doesn't have an AF gauge). Idle is set to 900rpm.


Idle: -50mV
3000rpm, no load: 550mV
3500rpm, no load: 600mV

Idle, Blue relief solenoid connector pulled: 850mV

Idle, TPS disconnected: 750mV
3500rpm, TPS disconnected: 750mV

Idle, switching solenoid vac line disconnected (and plugged): 800mV
3500rpm, switching solenoid vac line disconnected (and plugged): 800mV


Looks like this confirms that the O2 sensor is operational, and the airpump system is working at idle.
Eventually I realized that my extra tests weren't all that helpful, as the split air pipe would be pumping air AFTER the O2 sensor.

Yeah. There's a *deal* in the FSM where they use a Code Checker/Tool connected up to the six socket TEST connector in the engine bay. They have the operator disconnect the neutral switches connector on the transmission, then slowly rev the engine, and at something like 1700rpm a green light on the tester is supposed to Flash a given number of times per second to show the 02/ECU is going into closed loop.

The same thing can be done with a single LED going to a couple of pins in that six socket connector and just putting the shifter in any gear i.e. out of neutral, then reving the engine over 1500-1700 or so and the LED will flash just like the big buck Mazda tester would.

I did that *deal* from the FSM from memory. Too lazy to double check the FSM.

Actually if the thread owner wanted, he could leave that meter connected to the 02 output and go for a ride at say a steady 60mph or so. The meter should start to bounce around when the ECU goes into closed loop,.

I'm not sure why your car didn't pass. The thing seems to be working right. Ah, fudge. I forgot to check the 8second thing. Maybe a bit later.

Are you 100% sure the timing is right? Have you lined up the yellow mark on the front pulley with the tick and popped the CAS lid?