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[Essex_Andy]

Last weekend engine oil change, new oil filter and new fuel/petrol filter. (done this plenty of times and 100% confident on my ability etc)

Since then the car 'lurches' occasionally on part/light throttle. Then other times runs 100%.

Plugs are 2 years old. So are the HT leads.

No fault codes, no EML either?

This weekend I'll remove the plug caps and check for oil but oil level hasnt changed since oil change and oil level was constant before oil change.

I fitted OEM cam cover gaskets about 18 months ago.

Sounds/feels like a miss-fire and occasional backfire...but sounds like a back fire into the intake not 'bang' from exhaust.

Any ideas?

[feeutfo]

filter right way round? Oil in plug wells?

[Essex_Andy]

Petrol filter deffo right way round...been under and checked it this evening.

Can only think oil in wells or maybe O2 sensors in exhaust? ? ? ?

Yet no smell of burning oil and no change at all on dipstick? ? ? ?

[VX1]

Last weekend engine oil change, new oil filter and new fuel/petrol filter. (done this plenty of times and 100% confident on my ability etc)

Since then the car 'lurches' occasionally on part/light throttle. Then other times runs 100%.

Plugs are 2 years old. So are the HT leads.

No fault codes, no EML either?

This weekend I'll remove the plug caps and check for oil but oil level hasnt changed since oil change and oil level was constant before oil change.

I fitted OEM cam cover gaskets about 18 months ago.

Sounds/feels like a miss-fire and occasional backfire...but sounds like a back fire into the intake not 'bang' from exhaust.

Any ideas?

I would have replaced the plugs and leads if they are two years old. Replaced the plugs on my brothers astra over the weekend and when i looked at the old plugs they certainly needed replacing thats for sure.

Paul  

[Essex_Andy]

Set of leads for a V6 is about £80-90

I'm intending to replace it before the end of the year and dont want to 'throw' money away.

[tunnie]

accidentally disturb an o2 sensor on the zorst while doing the oil filter?  :-/

[Essex_Andy]

dont think I did..I have one of them there three leg adjustable spider filter wrench thingies that fits my 3/8's ratchet.

Just thinking what can cause a miss-fire but no error code or eml? ? ?

I'm 99% its fuelling/spark related. Have to see what the plugs are like on the weekend.

Thing is all is good when car/engine is cold....as soon as engine temp gets to norm miss-fire/splutter/lurching appears? ? ? ?

[Essex_Andy]

I did give a bloody good squirt of carb/choke cleaner into the throttle bodies and cleaned the MAF in meths.

Why I think possibly fouled plug(s)

Also new air filter just to rule that out.

[Andy B]

.....
Thing is all is good when car/engine is cold....as soon as engine temp gets to norm miss-fire/splutter/lurching appears? ? ? ?

as Tunie says then ... O2/lamda sensor. The car runs off the temp sensor till warm then switches to lamda.

[Essex_Andy]

I dont need to bleed the fuel rail if changing fuel filter?

I thought pressure from the pump will/should prime the system?

[Essex_Andy]

.....
Thing is all is good when car/engine is cold....as soon as engine temp gets to norm miss-fire/splutter/lurching appears? ? ? ?

as Tunie says then ... O2/lamda sensor. The car runs off the temp sensor till warm then switches to lamda.

Ok lamdas out and clean up in carb cleaner

[dbug]

I dont need to bleed the fuel rail if changing fuel filter?

I thought pressure from the pump will/should prime the system?

Didn't when I changed mine - and no probs.

[feeutfo]

.....
Thing is all is good when car/engine is cold....as soon as engine temp gets to norm miss-fire/splutter/lurching appears? ? ? ?

as Tunie says then ... O2/lamda sensor. The car runs off the temp sensor till warm then switches to lamda.

Ok lamdas out and clean up in carb cleaner

Surely there would be a code if the 02 sensors where unhappy?

[Essex_Andy]

Now I'm confused.....since starting this thread the car has run fine 90% of the time.

Do I live with it until the replacement car arrives hopefully by December or investigate and possibly make it worse?

[SteveMJ]

Is the dipstick and oil filler cap correctly seated?  If not there could be an air leak that will confuse the ECU.   The actual airflow is not through the air flow sensor.

Steve