Idle problem.
 

Hello everyone. I am having an issue with my engine idling erratically. Engine was just rebuilt with a full engine reseal kit. Everything is stock except the intake and exhaust. All vacuum lines were replaced along with wires, plugs, etc. As you can hopefully see by the video, the engine idles fine with the boost sensor vacuum hose disconnected but as soon as it is re-connected, idles fluctuate up and down. I tested the switch and the voltage was within range; vacuum hose connected and disconnected. There is a valve that is in line with the vacuum hose and it has a directional arrow on it. Is that supposed to be a one way valve and the arrow should be pointing to the valve correct? Any advice would be greatly apprciated. Thanks in advanced.

http://www.youtube.com/watch?v=riifSioMHZY

side note: There is also smoke coming from turbo area. I did install a USED turbo on the engine. Is it possible that along with the smoke, the turbos is not functioning correctly hence causing the erratic idle when I connect vacuum to the boost sensor?

ND. Good idea with the video. I don't confess to be a RX7 specialist but after reading your description of the arrow direction, I went out to the garage to have a look at mine. Mine is a stock non tampered 92 JDM. The direction the arrow is pointing is away from the boost (Map) sensor and towards the engine. I was just testing the sensor and if I remove the vacuum line from the sensor it wants to stall and idles rough. If I follow the directions on the Service Manual, and plug the line and apply -19.7 inHg vacuum with my tester to the sensor, the engine idles smooth. Maybe try reversing the valve.

The "valve" in line to the MAP sensor is a filter, not a check valve. Make sure you didn't swap it out with a check valve. You should be able to blow through the filter both ways easily.

Smoke from the turbos is no big deal, on a new engine you'll have smoke for a while as crap burns off. A new engine will smoke like a bitch typically - all the greasy handprints, cleaner residue, you name it.

The idle system on the FD is pretty damn simple. The throttle body should be fully shut at idle. The ISC (idle speed control) on the upper intake manifold is a pulsewidth-driven valve that opens and closes a certain amount to let air around the throttle body to set the idle speed. Think about it, an engine needs air to run, if you have no air (ISC closed, throttle body closed) the engine would stall. Give it a small amount of air and you have idle.

If the idle is going funny, you could have air getting in around the throttle body from somewhere else - a vacuum leak. Anywhere between the throttle body and engine is a possibility. It can be a badly installed block off plate, a vacuum cap that's not on, a gasket not flat somewhere, most anything.

Do you have a PowerFC on your car? If so you can look at what the sensors are telling you and see if there's anything that's out of whack.

Dale

Ya Dale, I was just doing some more reading and the valve is called a gas filter in the vacuum hose diagrams. It's definitely not a check valve. Thanks for the explanation.