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Discussion Starter #1
can anyone help with my car? Astra 2.2i z22se. It's developed another interesting problem... Sitting idling, randomly it will develop a misfire when started, sounds like it's only running on two/three cylinders, if I Rev it, it picks up and then runs normally... Sometimes I feel it misfire when stomping on the pedal.. Sometimes it runs fine

What I've done so far: swore at it (no difference) swapped a coil pack, thought this had improved it however when I went to start it it was clearly missing on at least one cylinder.

I don't have any dashboard lights on, or a machine for diagnosis, I've tried running it with aircon on, and it makes no difference, still lumpy and idling at 750rpm.

I did notice too it was self medicating with fuel, revving itself up to 1500 revs when moving with no throttle pressed..

Where do I go from here? New spark plugs I'll do that, if that doesn't cure it I would have guessed a fuel filter would be next thing? (although weirdly it has no problems after 3200rpm and will sit happily in any gear so long as it's revving above this).

Any help or advice would be good, thanks James.
 

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Discussion Starter #2
So I've been doing a bit of reading online, they're suggesting it would be worth while replacing the coolant temperature sensor (£10) as well as the spark plugs, it apparently controls the ecu fuel delivery and it could be that the car is over fuelling the cylinders causing a misfire?

I'm not a mechanic by any means but I can replace basic parts, I would rather be certain I was replacing relevant parts though :rolleyes:


Something I should have mentioned earlier is that I tried it from a cold start and the engine turned over and over and wouldn't start, eventually it started lumpy and after a quick rev idled normally.

I'm guessing these symptoms add validity to a poor fuel mixture rather than an intermittent spark plug? :confused:
 

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I had similar problems on my astra z22se a few years back. Turned out to be a stuck egr valve. Took it and gave it a clean. Problem sorted.

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Make sure it has the right plugs too...
Genuine GM work properly (as do one of the NGK offerings but I forget which).
Coolant temp sensor is one of the things we changed on our z22 when we first serviced it.
Any replacement coil pack should be genuine too..

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Discussion Starter #5
I've replaced the coil pack from another car that was running properly, it's a genuine ecotec stamped coil pack, I'll have a look for this egr valve and see if I can do anything to it if these two things don't cure it.

Thanks James
 

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Ours has no egr.. previous owner removed it and fitted a cheater..
Have a butcher's on Facebook z22se owners and also z22se.co.uk
More specific knowledge there than anywhere else...

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Discussion Starter #7
It definitely has one, I can normally hear the exhaust note change as it opens under deceleration, you can flick it open (no throttle) and close it with throttle imput (if you're sad like me lol).
 

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Discussion Starter #8
It's similar to the exhaust retarder in hgvs, except they usually have a manual button you can use, to save the brakes on hills etc
 
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