I don't think this problem is the WUR. The AAV will allow more air/fuel into the engine when it's cold. This is why the idle is higher when cold, the goes down as the AAV warms up and closes. It looks like you have changed most of the ignition system components. I would look at the fuel system as the next likely culprit. You can take the injectors out, and soak them in cleaner. For the FD, just run some bottles of fuel injector cleaner through. With the injectors out, you can set them up to spray in bottles to see if they're all in spec. This also tests the FD. One or more injectors could be clogged, or a slit in the FD could be clogged, causing a lean mixture in that cylinder. Also, you could still have a vacuum leak somewhere. Maybe intermittent. Get a cigar, and blow smoke into the system to see if there is a leak.
After putting the rebuilt, correct model, WUR in I don't think it's the problem either. I do think it was money well spent, however. I expect the injectors are most likely original and yes I bet one or more is not operating correctly. I'm going to replace them as I've read enough accounts here that it will be money well spent as well. As far as a vacuum leak that is of course possible. I have had them before, little slits at the fittings, etc. I have replaced just about all vacuum lines and examined what I haven't. I will look again. Man last time I smoked a cigar in the garage it stunk for a week! Yesterday, before the car died I am pretty sure I noticed the AFR go excessively lean before stalling, as if the car ran out of gas. I still need to deal with the idle issue and get that right on cold start. What I don't understand yet is how the AAV works (I've read the primer)—does it just drop the idle a predetermined amount or are there some smarts in the system that give it a target RPM? The AAV is electrically connected to the WUR. The odd thing is the car worked well on the first 2, short drives (8-10 miles RT) this Spring and even passed inspection. Then one day after about 4 miles (car is now fully warm and fans are running) the idle dropped to where I needed to give it throttle at stop signs to keep it going. Then a backfire. To get it home I let it cool down and turned the idle up using the throttle position screw. It hasn't left the property since. Back at it today. Thanks for the video-good stuff.
The AAV is a device designed to increase the idle speed at start up. The theory is that the engine needs a higher idle at start up in order to run smoothly, until it's fully warmed up. The AAV is basically an orifice with a valve that closes as a bi-metallic strip heats up. The orifice allows more air to the engine while it's open. Of course this also allows more fuel into the engine as well. Try this test - remove the air filter box, start the car. When the idle drops down to 900 RPM and starts sputtering, press down slightly on the air vane with your finger. This will richen the mixture. I'm wondering if that would stop the sputtering, and backfiring.
Last Fall I tested the AAV with a heat gun and an infared pyrometer. Also made sure the switch operated properly. All OK (at least then it was). So if pressing down on the air valve smooths things out what would that indicate in terms of component failure or mis-adjustment? Thanks
That would tell you the mixture is too lean. Regardless of what the gauge says. Too lean = vacuum leak, or clogged FD and/or injectors. If this works, I would adjust the mixture screw to the rich side. Just enough to get her to stay running. Then drive around for a couple of hours. The goal is get fresh fuel through the system to clean it out. You can always adjust the mixture screw back if running rich. Make notes of your adjustments.
To spicedriver: I will certainly do that. I just need to get my idle speed up to the proper level if possible. I'll have a go at moving the "air adjusting screw" and upping the idle then try your test. Thanks very much.
Today while searching for vacuum leaks I decided to revisit the pipes to the air injection system (table 9 #3). I had looked at them last Fall and inspected one of the check valves (the one near the firewall) and found some corrosion and made a note to replace both valves. Last week I ordered new ones but unfortunately the supplier sent me two different sizes—so only one fits (and of course they are shut down for a month). I removed the check valve closest to the back end of the car, the right manifold, and found what you see in the pic below. The valve no longer works—air can pass both ways. There is a hole in the valve on the air intake side. Last week I found the the pipe going from the cut-off valve to the air filter housing was off (see post #53). I believe the lose pipe may have been the result of one of the backfires the car had. Can someone tell me the relationship between the air injection system and the fuel injection system? The car now starts fine but runs rough and rich. Thanks again guys. Image Unavailable, Please Login
Bringing fresh air into the exhaust stream helps burn off any unburned fuel from the combustion process. This is for lower emissions, and should not affect the fuel injection system. A lot of owners just delete the air injection manifolds, and plug the holes. If you do this, make sure to get the correct size plugs. https://www.ricambiamerica.com/qvaip-air-injection-plugs.html
Thanks for the clarity. I am wondering if a malfunctioning system would cause the AFR meter to read incorrectly? With that check valve inoperable could exhaust gas flow to the left back check valve and into the air filter housing? That can't be good.
No because the cut-off valve is also a check valve. Plus the whole secondary air system doesn’t do anything most of the time, it’s only real purpose is to burn off the rich mixture on cold start/idle to heat the cat up quicker. Regardless of that there is no way it would affect the air meter.
I suspect that the influence of the cold start injector is partially the cause for a overly rich mixture and erratic idle/backfire but wanted to be sure the circuit was working. It's a new injector. I made up a test light which is simply a 2 conductor wire with male and female AMP connectors and a 12vdc light in parallel. The idea is that I could see when power was being applied to the valve (the thermal switches that control the injector are on order). Starting up the injector definitely is energized with the light glowing. Unplugging the injector, restarting, and adjusting the air bypass screw a bit got the car running without the usual rough idle (which I conclude in my amateur way that it was due to the influence of the injector.) The AFR is also much more stable, however, idle is north of 2500RPM. When I try to bring it down it seems to low (about 1000RPM to keep the car running smoothly. Time for more study. Has anyone here ever had that happen to their car? Thanks Image Unavailable, Please Login
