What's causing my Jeep Grand Cherokee to misfire?

I have a dangerous misfire on 13 year old Jeep Grand Cherokee 4.0-litre petrol. When partly warmed up, it goes through a spell of chronic misfire on part throttle. However, when 100 per cent warmed up, it reverts back to normal. Any idea what's causing it?

Asked on 24 September 2013 by aceracer

Answered by Alan Ross

Well it could be a number of things.
1.have you checked the ign system/timing
2.ECT (engine coolant temp sensor)
3.TP (throttle position sensor)
4.MAP (manifold absolute pressure sensor)
5.Heated Oxygen sensor (HO2S) control
6.Idle air control valve
7.Park /Neutral position switch
8.ECM (engine control module) supply/earth
9.EVAP (evaporative emission cannister purge valve)
10.IAT (intake air temp sensor)

Unfortunately rather a long list , but would suggest that the check is done according to this list.

Tags: misfire technical issues

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