No idle
 

I've searched and can't find anything that helps my situation. My car is pretty unique, in a bad way, so other threads don't really apply to my car.

Anyway, I have a 87 with a T2 swap using the NA harness. Emissions, BAC, ACV; all removed. Basically just what you need to make it run (but not idle apparently). Also has 800cc secondary injectors and 3in exhaust with one muffler.

Now what part, or all of the problem might be, is that I don't have a IAT sensor, I got the rising RPM inlet duct, which comes with holes drilled out for 3/8 NPT. So could not having a IAT cause my car to not idle at all?

I can turn the idle adjust screw in and it get it to idle, however it almost sounds ported. Also when I do this the throttle will stick when I let off the gas for about 3 seconds, and then slowly drop down to idle.

I've searched for vac leaks and can't find any, TPS is set to 1v. Car runs good except for the idle. Also, on cold starts, it is really hard to keep the car running at anything below 2500 rpm, once it warms up I can just rest my foot on the gas it will hold around 850, but still sounds almost ported. The cold start thing almost makes me feel like it's a vac leak, but again I've searched everywhere and can't find one.

I'm going to try to find the adapter for the inlet duct so I can get my IAT hooked up, but I just don't see that being the whole problem.

Well, if the sensor port on the inlet duct is open, that would be a massive vac leak and wouldn't idle without throttle input. And it would most definitely sound ported, ask me how I know lol.

And, the throttle hanging for a few seconds could be the dashpot, but I don't know what the specified timing on how slowly it releases the throttle. It's just there so the plates don't snap shut when you let off.

Come on man, give me a little credit, it has a plug in it! :lol: I don't have a dashpot. And it only does it when I adjust the idle screw out to give it an idle.

I've been messing with it. I found that, if I adjust the TPS all the way in, it get's rid of most of the throttle hanging up issue, so right now I have a decent idle and it doesn't hang up too bad on decel, although if I hit the brakes the car wants to die unless I'm in gear.. When I have the TPS all the way in, I notice that with the car off, ignition on, I hear a click when I just start to push the throttle. I'm assuming that's the injectors. When I set the TPS correctly, I don't get the click because the plunger on the TPS is already too far out. It makes me think the injectors are still firing on decel when they shouldn't be.

I'm starting to lean toward the IAT sensor, maybe the ecu is defaulting out to a certain temp, or giving it extra gas sense it doesn't know the temp. It would kind of explain the trouble with cold starts as well, because the temp when cold would be even further from whatever temp the ecu is defaulting out to.

Injectors don't click w/key to on but the relief solenoid or switching solenoid would.

The Dashpot prevents the primary throttle from closing too fast on quick decelerations. Closing too quickly and the engine wants to sputter.

And it sounds like you have something binding w/the throttle linkage causing that particular issue.

Sorry, sometimes I even forget the little things like that, just had to make sure. I know without an IAT sensor the stock ECU will assuming a fairly nice temp, 68*F in the '88 FSM, but my MS3 will read -40*F without one. So, who knows what a failing one would read.

What does that solenoid do Satch? I don't have a dashpot, no binding in the linkage, it only does it when I have the idle screw adjusted out. If it's in, I have no idle, but the rpms drop normal when I release the gas.

thanks for the help guys.

The Relief Solenoid dictates where the air from the air pump goes. Either it goes to the ACV so it could be injected into the exhaust or the air gets dumped out a hose which runs under the airbox to the atmosphere.

The Switching Solenoid allows air from the pump to be sent to the Split Air Pipe.

When setting the TPS properly you will hear the Relief Solenoid click.

I have none of those things.