Following all the response posts from a few days ago, I've been experimenting paying particular attention to pulling away from stationary.
The car will pull away from stationary by engaging the clutch and without applying any pressure to the accelerator pedal.
It does this quite comfortably albeit it does not accelerate quickly, it would be fine pulling away on a quiet road but not say pulling out of a busy junction with a lot of traffic.
Of course after pulling away like this after a few seconds one has to depress the accelerator to come up to speed which is when the brief hesitation occurs.
I then asked myself the question would this work when pulling away from stationary on hill? And yes it did on a moderately steep hill.
I further tried it on quite a steep hill, I couldn't quote the percentage incline, suffice to say it was of such steepness that required the handbrake to be pulled up more forcefully than usual to hold the car on the hill. So, with the car in first gear, and no pressure at all on the accelerator, the engine is on tickover, I engage the clutch slowly and the car pulls away. I was surprised! Therefore I assume the ecu is opening the throttle and increasing the amount of petrol and air into the engine and hence the engine has the required power to pull away on the hill, but without increasing the engine RPM, it remains more or less on tickover.
I'm surprised by all this, being "old school" I thought all cars had accelerator cables to actuate the throttle within the carb or throttle body! That was until buying the Fiat and looking into all this did I realise the throttle is advanced by some sort of potentiometer on the pedal and presumably a solenoid moving the throttle butterfly.
I removed the VVT solenoid, cleaned it with carb spray cleaner, oiled it with engine oil and replaced it - I thought this might bring a result because when I bought the car in April I believed the oil had not been changed for some time, the oil was quite dirty another give away the oil filter had rust on the outside! I've never seen rust on the outside on a car's oil filter before. So driving it after cleaning - no noticeable difference!
I then cleaned the MAP sensor and driving it after there seemed no noticeable difference!
I'll try a further clean of the throttle body on the next session.
It won't be a big deal if this hesitation isn't resolved. And I'm half expecting it won't be! Though I'm finding out new automotive stuff!
