hey all,
i did a swap in a 96 dx, 1.6L sohc non-vtec couple manual trans. swapped in another base 1.6L sohc. old motor had 250k and burned oil, so swapped in one with only 46k on it out of a car driven by an old lady car does not have power steering, but the new engine came out of a car that did i think because it had the bracket on it. anyway, everything went ok, except now, after i start it up and it runs for about a minute (cold start) it starts to idle all funky, up down up down up down constantly. i checked for vacuum leaks, i could not find any. i drove it a few miles hoping that it might adjust to the new throttle body, etc. - but that didnt help any (drives fine, except at idle) NO CODES either! engine light not on, and i checked with a reader as well to see if anything came up, but nothing. i figured disconnecting the battery to reset the computer or something, except the battery was disconnected for a long time while swapping the engine. wondering if anybody has any ideas before i start throwing parts at it.

P.S. on a side note ---- i did not drive or run the vehicle much before i swapped the old motor out, but i seem to remember the old engine having some sort of a slight erratic idle as well. they may be totally unrelated - the old one had issues, and a bad sensor on the new one, who knows. but just figured id let you all know.

any help is MUCH appreciated!! thank you!
andrew

 

What year did the new engine come out of?

 

Air in the cooling system will do that. Check that the radiator is completely full, not just the plastic tank.

 

the new engine was out of a 96 as well.
and i did remember that air in the cooling system will do that, which was something i was suspecting, but i knew the radiator was full so either there was a pocket of air somewhere or not.

i actually found the issue. the issue was of course the iac. i didnt suspect it since only 46k on it. i didnt feel like buying a new one, or swapping the old one cause i think it had idle issues as well haha. but i figured it out because if i plugged the hole in the throttle body with my finger, the idle came down and fixed itself. i then bench tested it by putting power to it and nothing happened. bench tested the old one, and it worked! so swapped them over, and good to go now!

thanks everybody!

 

What is the IAC?

 

Idle Air Control. bolted to the throttle body. it adjusts to allow proper amount of air to pass through the throttle body during idle at different times. two small coolant hoses coming out of it (for identification purposes)