running problems

[samanco]

can anybody help me, my galant 2.0 sport 2001 51 was spluttering and hesitating when accelerating from low revs and check engine light was on, i used rac scan tool to determine problem and it brought up o2 sensor 1, i have replaced this part with genuine mitsubishi part and and erased fault code on scanner, the engine light is still off but i still have the same problem. i have recently changed oil and upgraded spark plugs to iridium, however air filter is due a change./wall /wall /wall

[Nick VR4]

Check your spark plug gap would be the first step

[samanco]

i did buy recomended spark plugs but i will gaps

[White Lightning]

How long were you running it with the engine light on? I am just thinking that if the ECU was running in limp home mode it might have been running really rich and if you have driven it like this for a while it may have damaged the cat.

Just an idea ...

[samanco]

if cat was damaged would it be picked up on o2 sensor 2

[White Lightning]

I am not sure ... it certainly wasn't when I had the problem on a (piece of junk)Vectra a few years back. But the cat was so knackered on that it would not even rev above 2500rpm!

[Bat]

Hi,
The O2 sensor can only measure the exhaust gas mixture before the cat. It's only cars that are about 3 years old or less with 2 lambda sensors pre and post cat that can monitor cat performance.
The O2 sensor was probably not at fault but the ECU was seeing the O2 from the misfire and thought the sensor was faulty.
Misfire could be coils, leads or plugs, or possibly wiring to the coils.
Cheers,
Gavin :)

[samanco]

my car does have the two o2 sensors post and pre cat, a while ago light was on so i scanned car at garage and it brought up misfire, and throttle position sensor but light went out by its self and car was running fine, so could possibly be leads or coils will try.

[KEENY]

i had this problem and it turned out to be the dizzy cap. well when i say i had this problem i ment the car was spluttering and hesitating when accelerating and cut out a few times as well.