unstable engine

[sherif3soliman]

the engine keeps getting high and low as if the idle is not working fine,
but i changed the idle and it still doing that,
i thought it might be the fuel pump or the injectors, i did put my friend's injectors and pump,
nothing changed.
so there is nothing to change except for the fuel pressure regulator
i want to check 1st wether its working or its the defected part ????

[PrecisionBoost]

Personally it sounds like the ECU is the one changing the idle.

I encountered a "high-low-high-low" idle issue when swapping daewoo engines one time a few years back, the ECU was for an automatic and we put the engine into a car with a manual gearbox.

In the end we solved the issue by replacing the ECU with a different one from a manual gearbox.

Do you have an automatic or a manual ?

If you had an auto then perhaps there is a communication issue between the ECU and the Auto gearbox.

[MMamdouh]

we had such issue when we swapped the 2.0 engine into the nubira... turned out to be a faulty TPS... the CEL didn't turn on during this high-low-high-low symptom

MMamdouh

[sherif3soliman]

its manual, besides that i didn't come near the ECU nor the engine .
so i am going to clean the throttle and the sensor or change that sensor and try so as to see any changes.
thanks guys for your help,
am going to inform you what will happen