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Discussion Starter · #1 ·
Still trying to find my over fueling fault.

Have replaced CTS and have also tonight, just checked the timing and all seems fine.

I am still getting a lack of performance and also, when it's warm, it takes a good few turns of the key before it splutters into life. When cold it starts as is it should.

No fault codes on the ECU. Although the ECU did flash a bit 2 weeks ago. Now it's fine. No codes on it then.

I might go and buy another o2 sensor tomorrow, but I haven't much money, so want to check other avenues.

AstraDan doesn't trust them and as the o2 sensor is about 10 years old, it might be advisable to replace that.

Due to the crap that gets covered on them, their own lifespan etc. It should make some kind of a difference even it it's not that which is entirely the fault.

Any ideas anyone?
 

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When Kirstys o2 sensor was duff on her GSi Cav she got the ecu light at about 4k rpm iirc.

Dunno whether they're the same mate, but I have the o2 sensor of the X16XEL we took out of the Astra... check the plugs are the same, if it's any use I'll send it out for you.
 

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Discussion Starter · #4 ·
Cool, could give it a go. Might eliminate any problems.

Well, originally, my ECU light did the same, but didn't store any codes. It's not doing it at the moment. Maybe it's falling within range.

Is that 02 sensor a 3 pin version?

Cheers
 

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02 sensors can cause bad mpg without a fault light, yes - just had the this on the Vectra - I found a dodgy plug lead beforehand which was causing the odd misfire, and I suspect unburnt fuel had poisoned the sensor over time.

a good way to check is to reset the ECU (which will clear the adaptive map settings) - and keep an eye on the mpg over the next 300 miles - if it returns to normal, but then gets worse again, it's definitely the 02 sensor.

I replaced it for a pattern part from http://www.oxygensensors.co.uk/ - just did 950 miles to £90, so I think it's fixed now :)
 

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Discussion Starter · #8 ·
I have reset the ECU and fueling has remained bad.

I think unburnt fuel and age have killed mine off. I remember cranking the engine after AstraDan and myself fitted new cam belt and rollers, neat fuel will have gone into the exhaust and may have killed off the aging sensor.

I have had a slight miss or stutter on pulling away in 1st gear. Car struggles a bit to start when warm.
 

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doubt the problem is the sensor then Si, if your sure that the ECU was properely reset - resetting the ECU should return it to the default map, which obviously will take time to be modified.

best thing to try is to reset the ECU, and leave the sensor unplugged - although the limp map is probably a bit rich for safety, it won't be so bad as to cause overfuelling to the extent of a misfire - the ECU will also use the CTS instead.

the last thing you want is to replace the sensor, which is then killed by an underlying problem
 
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