Vauxhall Nova (1983 - 1993) - 1.2i misfire under acceleration-idle speed ?

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Thu 16 Aug 2007 20:47
1.2i misfire under acceleration-idle speed ? - none
Have been asked to have a look at a basic Nova 1.2 i
The car starts fine from cold (and hot) but during the warm up period there is a very noticeable misfire under acceleration - it's ok when stone cold or hot. The temp gauge barely moves off the blue bit even after an hours running, and the idling speed is erratic at all times - usually a bit to fast.
I intend replacing the thermostat, plugs and leads - but any info on sorting the idle speed would be a great help. TIA

Slight tweak to subject line to identify model and problem. - PU
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Fri 17 Aug 2007 01:13
Nova 1.2i misfire under acceleration-idle speed ? - Dynamic Dave
You'll find replacing the thermostat will probably help with the idling speed & misfire. As the engine isn't getting up to temperature the electronics controlling the fuel mixture are probably making it run too rich (think back to days when cars had manual chokes)
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Fri 17 Aug 2007 10:25
Nova 1.2i misfire under acceleration-idle speed ? - Ruperts Trooper
Small engined Novas always ran cool, temp gauge just above the blue on our '90 1.2 carb model.

Even if it is running cold, the injection system shouldn't cause a misfire or uneven running, it needs the extra fuel if it's cold - it'll just use a lot more fuel!

Personally, I'd start by using Redex Injection Cleaner to get rid of any condensation in the fuel tank and to un-gum the single injector - we are talking about a 13-15 year-old car here.
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Fri 17 Aug 2007 22:42
Nova 1.2i misfire under acceleration-idle speed ? - none
Thanks for replies.
So nothing to adjust, clean or tweak then ?
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Tue 25 Jun 2013 11:09
Nova 1.2i misfire under acceleration-idle speed ? - DJ Drive K

Hi all, i gotta 1.4i 1991 nova, and once warm-hot, it misfires badly at low revs under load. i've renewed HT leads ,dizzy cap, rotor arm, and the plugs are only 2000 miles old...and a bit black when i took them out.

I have tried Redex, and no change.

MPG is down compared to normal also.

Now, the heater inside car is rubbish in the colder months, so i do have a new thermostat and water pump to be fitted when i get time...or when the car starts to play up. Would a busted thermostat give misfiring problems? I read nova's do run cold, mine has done in the year i've had it, the engine has only done 44000miles.

I still have ignition coil to renew, but is it more likely to be the thermostat causing the misfire once warm. Strikes me its an engine temp issue, or could it be the Lambda sensor? I have no warning lights on the dash though to suggest this.

Will do water pump & thermostat next week as i'll be off work anyway, but just tryign to understand whats going on.

many thanks. Marty.

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