190e 2.6l o2 light / rough running problem

Jul 15, 2003 2 Replies

This car is a friend's and I've helped with it extensively. Symptom: The car will buck / cut in and out and flash the o2 light Cause: unknown - happens intermittently - car has done this for *years* but recently it happens more regularly.



Attempted fixes:



- new ignition components (wires, plugs, cap and rotor)



- vacuum hose fixes



- general clean-out and checkup of fuel distributor



- new OVP (OLP?) relay



Historical fixes:



- new o2 sensor



- new fuel pressure regulator



It doesn't feel like a fuel issue - even bucking and kicking the car has decent power and will increase in RPMs during an 'episode'. It feels like ignition; like it's missing on a cylinder or two or three.



Any guesses?



I'm going to check wiring and fuses as best as I can to be sure there isn't a short somewhere or a loose fuse causing the computer or other electrical controls to malfunction.



I haven't been able to reproduce the problem in-shop so it's hard to know if it is actually not firing on some cylinders.



Thanks in advance for your help!



Damian


I'd check:

  1. the wire to the O2 sensor for being broken inside its insulation

  1. fuel pump pressure and output volume

  2. the crankshaft position sensor - if this engine has one

  1. otherwise, the ECU - engine control unit - and its connections

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