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Discussion Starter · #1 ·
Car: Vauxhall Astra Hatchback, 1.4, Petrol, Manual, 5 door, Engine is Z14XEP

Update: I have already replaced all spark plugs, coil pack, used Redex a few times. 02 sensors have come back on OBD2 scanner. I have also disconnected MAF sensor and issue persists.

Issue: A handful of times the car has started and had an obvious misfire within the first 30 seconds of the car being started which then goes away and doesn’t come back. Now the car starts up and the rev counter needle moves ever so slightly up and down around 800 and 1100 ish revs. I can’t seem to find the issue causing this. In addition to this, the swirl flap has a delayed reaction on startup, it’s also knows as Air Intake Manifold Control Valve which I have ordered.

Please let me know if there is anything else I can try/test?

Just thinking out loud, can it be something to do with the injectors, camshaft sensor, crankshaft sensor, purge valve? Once the car has started and I rev a little in neutral it seems to go away. It only happens on startup at the start of the day when engine is cold.
 

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Are the O2 sensors the only codes you are getting? That may be your answer.

Can your scanner monitor O2, fuel trim, and MAF sensor data real-time? That can help narrow down issues.

Did you check the spark plugs for proper gap?

Cleaning the throttle body can help with poor idle (assuming you can do that on the 1.4). Especially the edges of the butterfly valve and the section of the body that interface with the edges.
 

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Discussion Starter · #3 ·
Are the O2 sensors the only codes you are getting? That may be your answer.

Can your scanner monitor O2, fuel trim, and MAF sensor data real-time? That can help narrow down issues.

Did you check the spark plugs for proper gap?

Cleaning the throttle body can help with poor idle (assuming you can do that on the 1.4). Especially the edges of the butterfly valve and the section of the body that interface with the edges.
I’m not getting any codes at all. I have done real time tests on all of the above and they came back ok. I have also removed the EGR valve and throttle body, cleaned and refitted. Spark plugs also replaced and checked. Let me know if I can check anything else. The swirl flap has a delayed response on start up so do you think this could be the cause giving it a rough idle on start up?
 
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