update: just change the ecu wif 2291 eci+rechip..now fuel regulator set to 2kg/cm2++ finally back to normal..but got another issue.. when step to padel, the engine 1st stall like to stop need to rev abit..the worse case when a/c on..rpm drop very bad and sumtime the engine die even during drive at low speed(gear 1 looking for parking) what maybe the causes??
hi dking... just a few suggestions :
1. have you checked all vacuum ports in and out of the intake manifold if they are connected properly including from the rocker cover to the air ram, manifold to rocker cover, throttle body vacuum hoses to the Fast Idle Control (FIC-MMC) unit located at the firewall, and from FIC to the intake manifold, connection to the EGR valve way under the throttle body, stuck to the intake manifold? Vacuum leaks commonly cause this sort of problem to G92/3 SOHCs (and sends false message throttle body's ISC at fault)... vacuum press too low in the vacuum circulation system will fail the FIC to actuate proper air control (purposedly force rev by the ISC leaking air from throttle body) into the intake, causing engine burdened by the a/c compressor drag to lose out. Or the ISC unit at the throttle body itself, especially the gears inside it - at fault and unable to open the valve that leaks air into the manifold.
2. have you tried advancing the ignition timing (by 1mm @ 2deg+-) and see if it's getting better or no improvement? Advancing ignition in the cylinder improves vacuum pressure a bit but this method is limited as it may lead to severe knocking. It it works - it does mean your vacuum circulation system have a leak or spoiled ISC motor/circuit.
3. If you have SAFC-II, check you TPS positioning voltage signal - might as well adjust the TB's TPS (Etc. > Sensor Chk > Thrt :) 0.49V to 0.51V position (if running on stock cams), or seek advise from mechanics who can tap a voltmeter to the TPS and do the adjustment. TPS set [V] value being lower than 0.40V can also cause the same symptom, unless your engine's ignition is high (nearly max out). Reminder - if you do so, you may see the fuel pressure increase - adjust the FP accordingly after adjusting the TPS.
Other than that -
a. are you using adjustable cam gear and adjusted it to be advanced?
b. are you using reprofiled camshaft, hi cam or wild cam?
c. are you experiencing miss ignition (little disturbances to the engine) while cruising at RPMs lower than 3400? (these disturbances clears out when throttle opened up)