Engine automatically idles at 0

[Andy348]

My tach has shown 0 at idle since I've done my B25 swap. It runs quite rough, shakes around and sometimes dies. I replaced my intake boot at one point and it seemed to go right to 700 for a split second, then back down to zero.

I recently replaced my throttle cable, so I adjusted the nut on the end of it to force it to idle at 800. It would do so (and would idle well) for 5-10 seconds and then readjust to 0.

Not sure where to start, but I'm sure it'll be with a smoke test?

[series88]

buddy had the same problem. To start, on the bad idle, he used the wrong spark plugs and one of his coils were dead.

By saying 0 idle, you mean tach isnt working right? his is the same. Have not figured it out yet.

[jlevie]

When doing an engine swap the battery is frequently disconnected for a good while. If the SI board batteries are pretty new they'll run down and that can cause what you are seeing.

There are a number of reasons the engine may be running poorly, but the place to start is by having a smoke test run.

[Chriskbmx]

depending on what year car you put the motor it in, like an early model needs to have the tack wires or speed wires? ran to the ecu. correct me if im wrong please.

[z122643]

Does it seem to "hunt" for idle? Meaning if you rev the engine and let the rpm's drop does it attempt to stabilize at all?