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Discussion Starter · #1 ·
Only recently realised that on the wife's ST If you turn on the ignition without dipping the clutch to start, all the usual lights come on the display and the normal ones go out eg airbag etc but oddly, also the oil pressure warning light!............Hold on, the engines not running. Why is this programmed to go out when there is no oil pressure yet? It's certainly not this way on my Focus RS, that stays on until the engine starts. As long as it does it's job after that initial procedure and the engine running, its ok but I do find it odd.馃

JohnD
 

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I had a look at mine but it has the electronic dash. Interestingly, when you turn the ignition on, there actually isn't an oil light!
When I put the "performance gauges" on, there's an oil pressure indicator, scaled 0-70psi.
So - when I start the car, the oil pressure sits at about 60psi. But it only stays there for a couple of minutes, after which there's a step change and it drops to around 30psi. Clearly there's something controlling this for cold start-ups. It's not a viscosity thing as it is a clear step change, not gradual.
It stays constant around the 30 psi level if you just drive "normally", and the boost gauge doesn't show anything.
Push the car a bit, see some boost, and the pressure goes up to 55-60 before falling back to 35 when you ease things back.
 

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Its probably like the Focus RS in as much as there is no real oil pressure measurement going on, its purely an 'expected' oil pressure considering oil and water temps and current engine rpm. Is there really no oil pressure sender unit on the block???
 

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Discussion Starter · #6 ·
Its probably like the Focus RS in as much as there is no real oil pressure measurement going on, its purely an 'expected' oil pressure considering oil and water temps and current engine rpm. Is there really no oil pressure sender unit on the block???
This was discussed on the Focus RS forums but there seemed no definitive answer. If it was the case, then using a different grade (weight) oil should have no effect on the gauge reading. I currently use Motul Sport 5/50 (USA spec. for this engine) as opposed to the Europs spec of 0/40 in the Focus RS and there does appear to be a very slight increase in the oil pressure reading on the gauge. If we assume the oil temp gauge is real, why not the oil pressure?
You must have at least, a genuine working oil pressure warning light. It could be the difference between catching the engine just in time and facing an engine re-build.

JohnD
 

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Discussion Starter · #7 ·
I had a look at mine but it has the electronic dash. Interestingly, when you turn the ignition on, there actually isn't an oil light!
When I put the "performance gauges" on, there's an oil pressure indicator, scaled 0-70psi.
So - when I start the car, the oil pressure sits at about 60psi. But it only stays there for a couple of minutes, after which there's a step change and it drops to around 30psi. Clearly there's something controlling this for cold start-ups. It's not a viscosity thing as it is a clear step change, not gradual.
It stays constant around the 30 psi level if you just drive "normally", and the boost gauge doesn't show anything.
Push the car a bit, see some boost, and the pressure goes up to 55-60 before falling back to 35 when you ease things back.
Excuse my ignorance here as the Fiesta is the wife's car so I know a bit less about it than my own Focus but is the 'performance gauges' an addition on the very latest spec? Her car is the '20 Performance Edition.

JohnD
 

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Its probably like the Focus RS in as much as there is no real oil pressure measurement going on, its purely an 'expected' oil pressure considering oil and water temps and current engine rpm. Is there really no oil pressure sender unit on the block???
Here you go...

Product Line Engineering Font Machine

Rectangle Font Number Parallel Screenshot

Item 10 is the oil pressure sender.

Rectangle Font Number Pattern Screenshot


Item 11 is probably the reason why I notice stepchanges in the pressure shown on the gauge -
Rectangle Font Circle Pattern Number
 
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