Engine Performance problem
2000 Vauxhall Corsa 4 cyl Front Wheel Drive Manual 70k miles
Over the past few months, I have been trying to track down the cause of a hesitation issue with my girlfriend's Corsa.
During accelaration, at some point approx between 2 and 3k rpm, the car loses power and the revs stop rising. After maybe half a second, the power returns and the car accelarates normally again. All well and good unless you're trying to get out of a junction - not good. No engine management lights appear when this happens. The issue seems to be more noticable when the car is warm for example when coming off the motorway and then stopping at a junction and setting off again.
To try and track down the problem the following have been tried:
Changed Coil pack with one from known working car
Changed Crank sensor (to fix another problem)
Changed Air flow meter with one from known working car
New Plugs and filters
Checked and WD40'd all connections and block connectors
The next (and last) thing on my list is the coolant temperature sensor. One thing I have noticed is that the middle copper core bit of this sensor, the bit that the spade connector slides onto, actually seems to spin round in the sensor body. Is this normal? I was just wondering could this be causing a loose connection. I can send a picture if need be.
Hesistation, stumbling, jerking and lacking the power could be caused by the following a lot of checking to do to nail this problem
About the CTS is shouldn't do that, best to replace it-
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)
Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include: Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires