swapped an auto d16y7 in my manual car now erratic idle??

[Shibby H22A]

my car is 98 civic dx coupe, the old motor went, bought an 98 motor out of an auto civic, for 375 bucks, 92k miles. installed it, runs great but erratic idle. i used the wiring harness that came with the motor. so there are some wires left that are used for the auto transmission. well i took it to honda, and got it plugged in, and it says vaccum leak. there is no leak to be found, so i swapped the map sensor, still the same issue. honda says i pretty much have to swap my old harness back in because the auto trans harness will cause issues.

is there any other way around beside of having to replace the harness? what could be the other causes? bad throttle body gasket? or what? the mechanic checked it all for leak, found nothing.

is there some wire that needs to be jumped, or modfied?

[eg6lsvtec]

im not 100% that its the harness,..have you checked you tI ACV...on the back of the intake manifold,..take it out & clean it or replace it,..that will DEFF> cause an erratic idle

[Targa250R]

Did you use the throttle body (with attached rotary air control valve) from the automatic engine, or did you transfer the throttle body over from the manual engine? I have a hunch that your idle problem is caused by a rotary air control valve problem. IIRC, D16Y7s use different RACV part numbers for automatic vs. manual engines. Look into that.

Shouldn't have bothered with the MAP sensor; I've never seen a bad MAP sensor in my life that wasn't physically damaged.

Typically, when you do swaps like these, you should just swap the entire intake manifold and wire harness over from the old engine to the new one to avoid any sensor, line, or wire compatibility problems. It's not much extra work at all while both engines are out of the car.

[Shibby H22A]

yea i didnt know it was an auto engine until i installed it and found those extra wires, and checked the reciept from the salvage yard, and there it says A/T oh well. i guess ill try swapping the throttle body first since its really simple and iacv too. if nothing works, i will just swap the harness before swapping the entire intake manifold. I will see how it turns out tomorrow.

[Shibby H22A]

well i swapped the throttle body, and the problem went away! so its all good, thanks for the help!