Double checking… with the engine warmed up
and at 2100rpm there should be no air coming out of the line that goes from the ACV to the air filter housing, and air should be coming out of the line that goes from ACV to cat.

At 2100 mine is pushing air to the air filter housing at about the rate of a hairdryer on low, and no air flowing from the line that goes to the cat. Assuming ACV is not working, so going to wedge it so air is always directed to cat to get me through smog.

Do I have everything right there? Manuals I have are silent on ACV.

And for your amusement, elec fan couldn’t keep up with the dyno at the smog place, and coolant shot three feet vertical out of the expansion tank just missing the smog guy. Gonna put the stock fan back on, and tape a line 2/3 up the temp gauge and tell the smog guy to stop if needle reaches that point.

 

Yes the valve is bad. Should only work on deceleration.

 

Th help pass smog, if memory serves me right I should cheat the air control valve so it always sends air to the port in the exhaust, and not to the split (rear cat) or air filter housing. Can anyone confirm?

 

That sounds right. I never had to do it myself. I talked with that guy Ken up in Oregon or Washington. Forgot his last name. But that's what he told me. He explained that the whole system just dilutes the exhaust with air on deceleration. So by rigging the valve. It dilutes the exhaust all the time.

 

yep, it works. the valve comes apart and there are a few ways to get "Port Air"
there is a rebuild kit for the FC and FD valves, its FDXU-13-991, not the easiest thing to find for sale

 

Couldn’t sleep last night so dug deep into the archives. Found this ACV chart for the exact year of the car I have (81).

Am in California and smog tests 15mph at 50% of the engine power, then 25mph at 25% of engine power. On all the test results have both speeds are run at 2100 rpm.

Given that CA tests car under load at 2100 rpm doesn’t this chart say I should be wedging the ACV to send air to the cat?

I know for sure the valve that decides if air is dumped back to the air cleaner is bad as air is always coming out of big pipe to air cleaner. Thinking I may wedge the ACV to block the route back to air cleaner, then assume the valve that decides if the air goes to port or cat is working.

Or should Ignore the rabbit hole of research and wedge the ACV so air is always to port. Have resistance to that as didn’t help me last smog go around. Have new cats since then, so not a clear cut piece of information.

 

I would wedge it anyways. That's your only option. You can't buy a new valve or rebuild it. The only potential down side to wedging the valve would be that it cools the cat down too much. Below operating temperature. But I don't think it will. Rotary exhaust is very hot. Just take the car on the freeway before u take it to smog. Get the cats good and hot.

 

PASSED! Wedged the ACV so that air to filter housing was always blocked. Reattached the ACV, removed the air hoses and found air went to port at idle, to rear cat at anything above approx 1000 rpm… which is what it’s supposed to do. Reattached air hoses, 1/2 hr drive to warm up cats and straight in to smog dyno. Made a MASSIVE difference! Take a look at these numbers.

Also had to put the stock hydro clutch fan back in for the smog test, elec fan couldn’t cope with the stationary dyno.

 

Glad to see you were able to keep C.A.R.B happy!

 

Some photos for Holdfast who was asking in Private Message exactly how I wedged the ACV. Pics below. Holdfast… check your message inbox, RX7club is telling me it’s full somI can’t message you.

I wedged the valve that is on the underside of the ACV when installed, so I removed the ACV to make it easier to get at that valve. Once ACV was off, took the cover off that underside valve and took a machine screw that was the exact diameter for it's threads to engage the flange of the valve when screwed in, and trimmed to length so that when the screw head reached the valve flange the screw shaft had wedged the valve open. Also had to use a machine screw with a low profile head, as anything taller prevented the cover from screwing closed. (I have a big box of random screws, luckily!). Pretty much anything that you can rig to wedge the valve away from the body would work, but the screw worked well. I reattached the ACV and tested with the hose to the air filter box removed and the hose to the cat removed. At idle you should feel no air from either hose, at anything above 1000 rpm you should feel air blowing from the cat hose, about the velocity of a hairdryer.

If this trick does not get you through smog, try new cats. If Californian and scratching by financially take a look at the CA Repair Assistance program which helped pay for my cats. https://www.bar.ca.gov/cap/repair

Probably more detail than someone experienced like Holdfast needs... but thought may be useful for someone new to RX7 trying to pass smog.

 

Got it. Thanks. But don't think it will help me with this 80 SA. System is a little different. Think it will cool the Thermal reactor too much. I got room now for new messages.

 

Rats. Check your messages, just sent you an idea.

 

Hope this is useful for others, as the above was useful for me.
Failed SMOG. HC and CO were nearly double limit. This was with recent rebuilt stock 12a and highflow "performance" cat with air injection. This combination barely passed 2 years prior.

Swapped Magnaflow front and rear CARB EO cats. Smelled like sulfer eggs. Tested ACV and no flow out air injection port, only flow out dump port return to intake.
Rotated dump port hose and connected to cat air injection tube. No more smell.
Passed SMOG.
notes:
all runs were 2100 2200 rpm despite my request for 1st and 2nd gear higher rpm 3000.

Previous failed smog test had problems passing gas tank vacuum test. I filled tank for passing test to reduce vapor volume. Also added grease to gas fill neck.

Shop's tachometer and timing light indicated 1950 idle rpm (actual 850). Timing light lit pulley timing mark indicator correctly but technitian did not understand leading vs trailing or 0 deg vs 20deg marks nor how to adjust his timing gun. I have repor with tech so he trusted my settings and I showed him dash tach.

Magnaflow cat has air injection port driver side with heat shield on top. I installed upside down with port on passenger side for convenience but EO numbers are not visible. Tech accepted my picture of cats prior to instal but very hesitant as this is not compliant.

If you're a California Democrat then **** yourself and ignore the above.