Rough Idle/Hard start after 5spd swap

[Marcus33]

So this may have nothing to do with swap but...
Since swap, the car takes much longer start. Turns over strong, then finally starts.
can take up to 6-8 seconds.

Worse once its sat for a while.

Also is having a bad bouncing idle at cold start, if it try to move it when cold, it almost stalls, takes a min to warm up, and ides completely fine after that.

Could i have wired something incorrectly? its a euro autobox, had the d/s/123 button, so the wiring was not as simple as in the DIYs

Do these cars have a separate idle setting when in drive, vs Park/neutral?

I believe my buddy had that issue with an E36 5spd swap, and had some idling issues.

or is this just random, and nothing to do with swap?

[Balleristic31]

Maybe you tore the intake boot or a vacuum line while wiggling the motor all around pulling/installing the transmissions. The wiring done for the 5 speed swap does not relate to how the engine runs as far as I know.

Did you disconnect the battery to do the swap? How many miles or how long have you driven it post swap? Might be the ecu just relearning.

[Seawolf]

What year / model is the car ?

If it's equipped with the later car C191 plug (round plug under the inlet manifold) and you didn't free the harness running to that plug when you canted the engine back you may have stressed the harness and have a broken wire or connection in the plug itself.

C191 feeds the injectors, temp sender and more importantly in this case the temp sensor that signals the dme to enrich mixture during cold start. If that connector is bad then the dme may not be getting the cold start signal - hence long cold start and lumpy idle.