2002 Cavalier 2.2 Sfi Idle problems/Missfire 105000 KMS on car

[Muttttly]

Hello everybody been fighting this problem for months now,easier to explain what I haven't done ,only gets a code when idling for a while in closed loop,sometimes ,po 300 most of time it jumps differrent cylinders rough idle, excellerates​ without issues,Starts great,I have replaced and checked vaccum lines etc Ok what I haven't done.
Have not checked fuel pressure,crank,can,knock, sensor hasn't been changed,rear ,02 sensor not replaced and ecu not changed yet.Everything else done literally..thanks

[Blue Bowtie]

You named it - Fuel pressure. Test that with KOEO and while running.

[Muttttly]

Internal leak of the intake manifold.
In case someone reads this.

[Blue Bowtie]

Internal leak? Care to elaborate? I thought the intake was still aluminum in 2002.

[Muttttly]

Originally Posted by Blue Bowtie

Internal leak? Care to elaborate? I thought the intake was still aluminum in 2002.

I have the 2.2 Sfi ....plastic intake manifold

[Blue Bowtie]

I have a '96 2.2 SFI, and it was still aluminum then. I wasn't sure when they switched.

[Muttttly]

Originally Posted by Blue Bowtie

I have a '96 2.2 SFI, and it was still aluminum then. I wasn't sure when they switched.

You must have a two piece manifold,As for mine yes the plastic one and it's warped causing a internal leak.