The stepper motor should not compensate your normal idling right? Only with the aircon on. Mine is 1991 4G63, so the higher the normal idling, so is the idling with air con on or maybe yours not the same:hmmmm:
can..but i prefer putting an oil catch tank...if filter alone aftraid got too much oil spilled from the hole...
When fitting that plastic fuel filter, make sure the seal from the hose into the filter is tight but not overly tight until the plastic is crushed. At the same time don't make it too lose until there's a vacuum leak. Both suck, trust me. Been there.
Duratec 272cam & stock throttle body or S90?
1. Are you experiencing throttle lag like you have to foot down the pedal more than usual to have the car going between 1000 till 2000rpm?
2. What's your fuel pressure setting?
btw... on most 4gx engine without fuel/ignition management hack and trims, and using cams 264°+, idling between 500-800rpm is NORMAL. Use S90 summore... lagi normal.
It's the same. I owned 4G93, 4G63, and 4G67 before and they all exactly the same with regards to the stepper motor. Even 6A12 also use the same.
Last night spent 1.5 hrs to DIY my idling.
1st : I check my TPS voltage, observed unable to get 0.5v on idling regardless how I fine tune.
Suspected my TPS faulty.
2nd: I disconnect stepper motor to remove noise from stepper motor
3rd: I'm additional to install another FICD (2 in total) to step up my air con idling after disconnect stepper motor. Observed idling still unable to move up from 500~700 rpm
4th: Disable breathing pipe as per poman input... Still the same.
5th: Replace whole throttle body, connect back back stepper motor and remove all FICD.
Observation: Idling is at 900~950 rpm after adjust on BISS
When turn on the air con, step motor is step up to around 750 rpm.
6th: Activate one of the FICD to further step up my idling.
Observation: idling manage to step up to 950 rpm at initial stage. However, re-compensate back by step motor after 1, 2 min. Now idling at around 750~800 rpm.
7th: Breathing pipe is still disconnect as observed idling speed more stable compared with connecting.
8th: Further increase on FICD air pumping to increase to 950 rpm
Observation: To be continue today after work
Lesson learn:
-One of the factor to have bad idling is TPS faulty / calibration out
-Intake manifold's vacuum is draw out by something.. or leaking.
-Stepper motor will compensate the idling as ECU pre-set idling when air con turn on
-FICD only can step up the idling when the stepper motor is at minimum position (Almost full close)
-Compressor with heavy load will step the idling down badly. Stock stepper motor unable to recover the pre-set idling even though with full open. Then FICD can help immediately.
---------- Post added at 09:46 AM ---------- 6 hour anti-bump limit - Previous post was at 09:30 AM ----------
Duratec 272cam & stock throttle body or S90?
1. Are you experiencing throttle lag like you have to foot down the pedal more than usual to have the car going between 1000 till 2000rpm?
2. What's your fuel pressure setting?
btw... on most 4gx engine without fuel/ignition management hack and trims, and using cams 264°+, idling between 500-800rpm is NORMAL. Use S90 summore... lagi normal.
Bro Kopi,
No throttle lag as just running with 6A12 throttle body. Currently run with stock fuel pressure setting pair with e-manage
but ut turns out still weird idling...untill i put double oil seal/o-ring on the engine oil filler cap...then only it behave normally... 
