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Merc320, UK Car Mechanic
Category: UK Car
Satisfied Customers: 298
Experience:  City & guilds pt 1 & 2
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Corsa D, Z14XEP engine. 120380 Km. Engine hunting. No fault

Customer Question

Corsa D, Z14XEP engine. 120380 Km. Engine hunting. No fault codes logged on 3x scanners. Voltage on map sensor goes up and down but not the MAP pressures. When driving, it is OK.
JA: Which particular sensor are you asking about? And have any trouble codes been triggered?
Customer: MAP (manifold pressure) sensor. On current data on scanner the voltage will fluctuate but not the manifold pressure (stays at 101Kpa). I don`t know if this is software on the scanner or that the sensor might be faulty.
JA: What is the make/model/year of your car?
Customer: Opel Corsa D, 1.4I, 2010 model. Z14XEP engine code.
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: I have my own workshop. I have blanked off all the vacuum lines going out of the inlet manifold to try and narrow down an air leak on the inlet manifold? On current data the O2 sensor stays at 0.917V which suggests an air leak. Eng computor is also over fueling on current data to compensate for extra air. Can smell the CAT overworking itself because of excessive fuel.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Please connect me.
Submitted: 4 months ago.
Category: UK Car
Customer: replied 4 months ago.
Just did a cylinder leak down test. Found valves leaking on no2 cylinder.
Expert:  Merc320 replied 4 months ago.


I would suggest removing inlet manifold and check for a bigger leak than that.

Please keep me informed.

Is the manifold aluminium or plastic. The plastic ones crack regulary.

Customer: replied 4 months ago.
Manifold is plastic.
Expert:  Merc320 replied 4 months ago.


I cant tell you how many of those i have fitted.

Please keep me informed

Customer: replied 3 months ago.
Why would the map sensor reading be 94kpa with ign on. Then after start up it will lock at 101kpa. Idling a bit uneven. Then on DTC there is no fault codes but I erase in any case while idling, the idling will jump once, then stabilise. Then the map sensor reading will be at 28kpa? Idling 100% evenly.
Customer: replied 3 months ago.
Input voltage at map sensor is 4.98V & output 3.83V which equates to 94Kpa after no fault code has been erased. With mechanical vacuum gauge connected the vacuum reads good in the top green of mitvac gauge.
Expert:  Merc320 replied 3 months ago.

I will opt out and see if anyone can shed a light on this.

Customer: replied 3 months ago.
Ripped the throttle body apart, cleaned and refitted. Seemed OK and also had the Engine computor software updated.
Expert:  Merc320 replied 3 months ago.