Just installed a m20b20 (motronic 1.3) that has been rebuilt with all new piston rings and bearings, the head was rebuilt at a professional shop and pressure tested and all new gaskets for the whole engine. Everything built as it is recommended. Fired her up and everything looks and sounds good and healthy. Idles perfectly when engine is cold and with no hesitation to throttle response.
The problem appears when the engine is warm (operating temperature), the idle suddenly goes down to 500rpm and even lower and the engine will hesitate badly when giving throttle and almost dies out and the car cannot be driven at all.
Things that has already been changed:
CPS
TPS
ICV (used)
AFM (used)
Spark plugs, Coil, wires and everything related
Fuel pressure regulator
Injectors (used)
Fuel filter
New fuel tank installed with all new fuel hoses everywhere
Fuel pump replaced some time ago before engine swap but not driven many miles. (I have tested the pressure right before the rail and seems to be high and good)
All vacuum hoses
Blue coolant temperature sensor
(the 3 items replaced with used parts was from my old engine so known good ones with no difference)
Only observation is that when I pinch (block) the return fuel hose from the back side of the fuel pressure regulator when the engine is warm the idle returns to normal (750-800) and the car will accept throttle and no hesitation and I even was able to drive it no problem with good power on the road.
Any suggestions? And why only when hot? I can take a video if that helps.
The problem appears when the engine is warm (operating temperature), the idle suddenly goes down to 500rpm and even lower and the engine will hesitate badly when giving throttle and almost dies out and the car cannot be driven at all.
Things that has already been changed:
CPS
TPS
ICV (used)
AFM (used)
Spark plugs, Coil, wires and everything related
Fuel pressure regulator
Injectors (used)
Fuel filter
New fuel tank installed with all new fuel hoses everywhere
Fuel pump replaced some time ago before engine swap but not driven many miles. (I have tested the pressure right before the rail and seems to be high and good)
All vacuum hoses
Blue coolant temperature sensor
(the 3 items replaced with used parts was from my old engine so known good ones with no difference)
Only observation is that when I pinch (block) the return fuel hose from the back side of the fuel pressure regulator when the engine is warm the idle returns to normal (750-800) and the car will accept throttle and no hesitation and I even was able to drive it no problem with good power on the road.
Any suggestions? And why only when hot? I can take a video if that helps.