Strange idle

[jozzze2000]

We swapped m20b25 engine into iX...after swap we noticed strange idle, it revs itself to 3krpm and back to normal idle, randomly.

If you try to rev it from idle and stop instantly same thing happens (@0:50 on a video bellow), any ideas?

Video

Thanks, J

[dnguyen1963]

We swapped m20b25 engine into iX...after swap we noticed strange idle, it revs itself to 3krpm and back to normal idle, randomly.

If you try to rev it from idle and stop instantly same thing happens (@0:50 on a video bellow), any ideas?

Video

Thanks, J

You just created a big vacuum leak in your system. Perform a smoke test.

[Sindako]

Dunno What Did you Do While The swap ?
Try To Start The Car With The MAF Sensor Unplugged . and Alos Check Out of Your Vacuum Systems .
But It's Really Weird .

[jozzze2000]

You just created a big vacuum leak in your system. Perform a smoke test.

I don't know where to perform smoke test, I've never heard mechanic shops in Slovenia had that test.

Can you please explain why did I create a big VL, I would like to understand that.

Dunno What Did you Do While The swap ?
Try To Start The Car With The MAF Sensor Unplugged . and Alos Check Out of Your Vacuum Systems .
But It's Really Weird .

We started with an early type of m20b25 with two "CPS" sensors on a bell housing...we replaced rear flywheel with a late type, also a front flywheel with "tooth" for a CPS sensor, complete engine harness and CPU.

Is it possible that TPS messes with us?

[dnguyen1963]

If you cannot find a shop to do a smoke test then I would suggest you look up the cigar method for smoke test in this website www.scottykilmer.com This method would detect large vacuum leaks, but not small ones. Almost 90% of strange idle problems are due to vacuum leaks.

[Sindako]

I was Goin To Say Check The TPS .
Otherwise The Flywheel Has nothing to Do With your Problem .

I'll Check it Out with my Friend from BMW , he Might Have Seen The Same problem .