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Car was running lovely, revs were a little up and down so I have all the leads a push.
I pushed the king lead, and engine suddenly cut out. Now it won't start again?
This car needs a witch doctor - it must be haunted.
Where did you push the king lead - at the coil or at the dizzy? It sounds like either the lead itself has busted inside, or where you pushed it has caused a weak point to give way. You ought to be able to firmly push the connectors without anything giving way. Check either the dizzy cap or the coil depending where it was you pushed it when it stopped. (If it's at the coil you can test for continuity using a multimeter.
Or a dodgy connection at the coil - I seem to remember the original problem had signs of weak sparks, or I might be getting confused with something else.
Could be.
What would you suggest next action is
I bought and just fitted new plugs, it's hunts when cold between 400 and 800 rpm. When warm it hunts around 1100 and 800.
Checked everywhere I can think of for an air leak. It may be my imagination but I think it fluctuated slightly when I push down on the TPS wiring/sensor.
Fuel pressure should be fine, as you can see wideband gauge, this shows the fuel/air mix
This is a video when warm (you can see the temp, it's spot on)
Also tried ANOTHER CTS, genuine Bosch this time.
its not about the middle its about the number. when revved it heads up to 17:1, very lean.
stolen from google but exatly what i wanted to say:
When discussing engine tuning the 'Air/Fuel Ratio' (AFR) is one of the main topics. Proper AFR calibration is critical to performance and durability of the engine and it's components. The AFR defines the ratio of the amount of air consumed by the engine compared to the amount of fuel.
A 'Stoichiometric' AFR has the correct amount of air and fuel to produce a chemically complete combustion event. For gasoline engines, the stoichiometric, A/F ratio is 14.7:1, which means 14.7 parts of air to one part of fuel. The stoichiometric AFR depends on fuel type-- for alcohol it is 6.4:1 and 14.5:1 for diesel.
So what is meant by a rich or lean AFR? A lower AFR number contains less air than the 14.7:1 stoichiometric AFR, therefore it is a richer mixture. Conversely, a higher AFR number contains more air and therefore it is a leaner mixture.
Leaner AFR results in higher temperatures as the mixture is combusted. Generally, normally-aspirated spark-ignition (SI) gasoline engines produce maximum power just slightly rich of stoichiometric. However, in practice it is kept between 12:1 and 13:1 in order to keep exhaust gas temperatures in check and to account for variances in fuel quality. This is a realistic full-load AFR on a normally-aspirated engine but can be dangerously lean with a highly-boosted engine.
Let's take a closer look. As the air-fuel mixture is ignited by the spark plug, a flame front propagates from the spark plug. The now-burning mixture raises the cylinder pressure and temperature, peaking at some point in the combustion process.
The turbocharger increases the density of the air resulting in a denser mixture. The denser mixture raises the peak cylinder pressure, therefore increasing the probability of knock. As the AFR is leaned out, the temperature of the burning gases increases, which also increases the probability of knock. This is why it is imperative to run richer AFR on a boosted engine at full load. Doing so will reduce the likelihood of knock, and will also keep temperatures under control.
There are actually three ways to reduce the probability of knock at full load on a turbocharged engine: reduce boost, adjust the AFR to richer mixture, and retard ignition timing. These three parameters need to be optimized together to yield the highest reliable power.
as an aside off boost the afr should be around 11.2:1, this should go to around 13.9ish on boost.
Watching that video, obviously our cars are totally different but mine idles like that unless on the choke on first start and I thought that was down to incorrect fuel/air mixture as my fuelling is well out at the moment
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