Post queries regarding your Mk3 Cavalier's fuel system (including ECUs) and exhaust here
#161891 by cavalier1990
Wed Mar 22, 2017 11:24 pm
Hi

Not really a biggy but noticed that not long after start up and putting light load on the engine it is spluttering like very choky and flat, low power. It isn't lurching or anything just you can hear engine sounds like it is very rich mixture, chuggy, and foot is down and not going so fast. It only happens about a minute or so after start up then it's gone. Recently replaced stat, not sure if maybe CTS or something over fueling perhaps.

Can CTS cause too much fuel at cold when it needs it anyway? Can it make it too rich somehow?

I can live with it but just wondering if is sign of something else developing or going to get worse. It is the 1.8 CNZ if you hadn't already guessed! :)
#161893 by Robsey
Thu Mar 23, 2017 12:11 am
Oh eck...
Chuggy and flat...
Could it be something daft like anbient dampness in the distributor or leads?
Or a leaky induction / vacuum pipe.

Not enough to cause a mis-fire, just a weak spark.

In your situation, I would go through the motions of a service inspection.

Check that : -
Plugs, leads, rotor and distributor cap are all clean and dry.

Check the operation of the hot / cold air deflection flap in the air intake housing.

Ensure that all vacuum pipes are secure and free from leaks or cracking.

And how old is the engine oil.

A faulty coolant temperature sensor often causes the idle revs to surge upto about 3000 rpm when the engine is cold.
Despite only being 'in the loop" when the engine is warm, a poorly lambda sensor can cause an over-rich mixture.
And - be aware that faulty sensors don't always put the engine light on.

And last but not least -
Ensure that all electrical connections are clean, dry and securely fastened.
Including the amplifier and coil on the passenger side inner wing.
And the battery leads of course.
And all the ground tags.

In my early C18NZ days (1995 to 2011), the usual weak spots were the lambda sensor, vacuum pipes and damp in the electrics of the coil and amplifier.

And as anyone will tell you, the C18NZ always has a slightly irregular flutter from the exhaust on idle.
#161903 by cavalier1990
Thu Mar 23, 2017 8:09 am
Engine runs sweet as a nut as soon as this stops. It sounds basically like flooding rather than spark I'm sure. Everything you mentioned has been checked previously and all sound especially after the rebuild. I'm wondering if it might be the lambda as I always had that problem with emissions at mot, although it was running quite well otherwise, no soot or anything.

Ticksover fine just when you put in under load and give it gas. First thing in morning I pull out drive up a slight incline you can hear it and feel it. Will of course give it a once over again. I did change the ICV a month ago, and if I'm thinking straight it did kind of start around about that time, although not saying it is related, and I think it did do this from time to time before but not as regular. Maybe that being replaced has exposed something else at fault.

I'm trying to see if we get a warmer morning (whenever that is) if it is worse or better. Trying not to be too picky with a 22 year old engine mind you!
#162204 by cavalier1990
Tue Apr 18, 2017 8:51 pm
Never noticed anymore problems with this as the mornings have been warmer, but this morning was cold and could feel the slightly flooding/choke but clears very quickly. Seems like overfuelling when it is cold i.e. air is cold. Would think CTS if it got worse and worse, but as it clears quickly not such a problem, will live with it and let it develop as they say, if indeed it is going to develop!
#162205 by Robsey
Tue Apr 18, 2017 9:01 pm
Just noticed that it is a 1.8...
Is the hot air induction pipe fitted and in good condition.
And is the hot / cold control flap working properly.
I think it is controlled by the very thin red vacuum pipe along the back of the induction trunking to the top hat.
#162226 by cavalier1990
Wed Apr 19, 2017 7:34 pm
Robsey wrote:Just noticed that it is a 1.8...
Is the hot air induction pipe fitted and in good condition.
And is the hot / cold control flap working properly.
I think it is controlled by the very thin red vacuum pipe along the back of the induction trunking to the top hat.


It has the hot pipe and is ok, not sure if flap is opening/closing right enough.

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