Won't idle when cold / auxiliary air valve / idle air control valve

[AntHamel]

When you start the van, does it run rough and want to die (or actually die if not given gas)?

Gwen

Hello, and thank you van gurus for this incredibly helpful thread. I’ve had ongoing cold start issues since I resurrected by 85 Van last year. I’ve narrowed it down to everything but this air valve. Cold start time switch is good (was replaced along with the Bosch connector), cold start injector passed ohm test and is confirmed to be working, I cleaned my throttle body when I did the TPS, I replaced all vacuum lines and verified there are no leaks, I even tried a spare ECU since I had one from the junkyard.

And still, when cold starting I got to put my foot on the throttle a little to get it to start. Otherwise, it’s exactly like Gwen describes here, I’ll hear it fire up but promptly die. I followed the on-vehicle check outlined on page FI-57 (that was quite a stretch with the longest pair of pliers I had) and it failed. No change in RPM.

So last night I pulled my intake and got the air valve out, and unfortunately it looks good, as illustrated in the repair manual??? Looks just like my other one, open just slightly at room temperature. Ohms are the same on both too, at 44.

I’m wondering if anyone knows a little more specifics about how these work. Like what’s the 7mm adjustment screw do? Does the heat coil change with coolant temp and then move the gate valve accordingly? If so then what is the actual electrical connector for? Or does it run off the ecu temp switch (which I have also replaced)? Lastly has anyone experimented with rebuilding these using parts from other Toyota air valves? I looked around online and it seems like other models had air valves just with different shapes.

I’m taking my fuel injectors to be cleaned and tested and I’m waiting on an intake gasket from rockauto, so I have a little while to figure out what I’m going to do. I would hate to put my new/old air valve in and have the same problem. Any input would be greatly appreciated, this forum has been a lifesaver.

[nobrush]

So I'm having this issue when I start my 1991 Previa. It would die if I didn't give it gas when cold until I set the idle up higher to prevent that. It can go up or down a bit (±200rpm) as I'm driving if I'm in neutral at a stoplight after it's warmed up but it works fine for now.

I took off the throttle body and cleaned it up as it was pretty dirty (cat safe cleaner), as well as removed & cleaned the ISC (I tested it with 12v and it seemed to open/close fine) & put on new gaskets for both. The problem is still there. I have replaced the fuel filter in the past when I had the issue before but I believe it was only an issue at stop signs since it's a manual and not idling low on startup like it is now. That was only a few years ago and it's a messy affair so I'm hoping to avoid that. I'm going to do a cap/rotor/wires/plugs tune up soon to rule that out since it's been 60k miles. (I'm at 407k miles!)

On a side note, I did pull a bonehead maneuver (I know really stupid) and pulled out the MAF sensor (or VAF sensor) which yanked on the "serviceable" soldering connections about 2 months ago. It wouldn't start at all and found this video showing me to pull off the jumper wires and just solder the pins straight to the board and it worked! I'm assuming that it has nothing to do with this issue as it ran fine for at least a month and a half before this issue popped up. This guy saved me a long drive to the junk yard. https://www.youtube.com/watch?v=CXCpYj-r_lI&t=714s