swapped in an ej22t...erratic idling

[VTbikerguy]

About 2 weeks ago, I swapped out my ej22t (after throwing a rod:( ) for an identical one with about 80k on it.

Now when it's warming up, the rpms drop so low that it studders like it's gonna stall out...then it revs up to about 2000 and repeats this over and over again.

My check engine light is on, and it's throwing a knock sensor code. But I can't see how that relates..

I used all my sensors from the old engine. The old engine would idle low and studder here and there, but never did anything like this. Any ideas?

[bakergtt]

Try swapping out your idle senser with the one that came on the "new" engine. Have you reset the ecu since you did this?

[Wiscon_Mark]

Clean out that IAC valve. Also, as a super temp fix when this happens, rev the engine up a little bit, and it should go away.

I find this only happens to me when the engine is warm, and I've shut off the car, and then start it up again. Otherwise the idle is steady.

[VTbikerguy]

The engine I put in had no sensors on it. Yes I did reset the ECU.

[SHOfast]

Vacuum leak?

[LunchBox04V]

I had this happen with my '93 EJ22 (non-turbo). It never gave me a code, but my '99 Second Gen EJ22 does the same thing, and gives me the knock code. I was just as confussed as you. I have not swaped the engine, but after about 12 hrs the CHECK ENGINE LIGHT goes out. Also, I put a custom intake on it has happened more often. ('93 EJ22 intake pipe, with a hole for the IAT and a K&N cone filter).

[bubaru21]

yea it sounds like a vacuum leak. i had this happen and found that my idle control hose had actually come off.