If possible, it would be good to use all the electronics from the Jimny. Only use the 'long block' from the Wagon R+ and bolt on the intake, exhaust, everything from the Jimny. Having said all of that, This sounds like it could be as simple as a vacuum leak. If the engine is fast idling rough when cold and then as it heats up tries to idle down and start using it's sensors (coming out of an open loop pre-programmed mode) So, either there is a gross vacuum leak, or one of the inputs is so far off, the computer can not compensate. After checking for vacuum leaks, check the O2 sensor for function, then check the coolant temperature sensor (the one that goes to the computer, NOT the dash gauge)
You may find something in those three checks that will help without needed to get into the diagnostic port.
Good luck, tell us how it ends!
-Eric
Thanks.
I have measured O2 sensor - its good. Its the original O2 sensor and I have extended the wires with crimp connectros that have soldering ring on them - dont know what they are called - quite expensice connectors, compared to normal crimps.
I have measured the temp meter that is located in the front, top of the engine. Took it out and it wasnt much off the recommendation in the Servicebook.
I have looked at the IAC valve.
He has had the intake off and put silicon onto the joining areas. I cannot get any reaction to the eninge when spraying with Brakleen.
The vacuum leak was my initiall idea - but I found no evidence of it.
The fuel pressure regulator itself holds vacuum. There is no fuel comming out of it when engine is running - not even several minutes after.
Spark plugs are new. Coils give spark.
I have some idea of perhaps the ECU (when the weather was colder the engine run better) or fuel pump.
He used all other electronics but the camshaft sensor if I remember right.
Where is the coolant dash gauge located? It doesnt work.