3d gen 3sge problems Options

[mi645]

ok having big issues with 3d gen 3sge
st204 swap. so turn on engine poor idle, idle jumps around 750-900 car wont rev smooth at sll anytime u rev it goes up then down to like 200 rpms ad back up to 750, seems like its running rich, new oem spark plugs and already black, was using oem parts that came with the engine so then trouble shooting i switched igniter off 5sfe switched tps sensor off my 5sfe the map sensor the distributor rotor, and same issue i need help!!!

[Rusty]

Yeah a few ideas, just trying to get more of an idea on what's happening, what's been replaced.

the idle sounds very off first idle should be ~1,800rpm and then after 5 mins or NOT should be a smooth 750 +/-50rpm


First things to check, that all sensor plugs are fully plugged in all the way. It's something simple, but sometimes overlooked.

Secondly vacuum lines:
MAP sensor: from the sensor itself, runs along the top acis chamber and plugs into the intake manifold just after the throttle body.
On the intake pipe:
Idle line/big hose, from the intake pipe to the ISCV which lives under the TB
Vacuum line/small, hose goes to a 'T' section hard line that goes to idle up and to the back of the engine, can't remember exactly where off the top of my head.


Sensors to check they are: clean & operate as they should
Idle Speed Control Valve (ISCV) - chances are this is dirty
Water temp sensor
TBPS - was replaced and was set right?

I wish I had a vacuum diagram of the gen 3, I have a gen 2 diagram