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Spi Starts Rough Then Smooths Out


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#1 masslaw

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Posted 12 February 2024 - 10:01 AM

When started first thing, the engine runs very rough, almost as if it is missing on a cylinder.  After a few minutes of driving, it smooths out and purrs just fine.  I'm not sure where to start looking for the cause. Eventually runs well so it is getting fuel.  Eventually runs well so all plugs are firing.  But something doesn't "kick in" right away when first started.  When warm it starts and runs properly



#2 slidehammer

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Posted 12 February 2024 - 01:31 PM

Is the fuel good and fresh? I have noticed if the car has stood and the petrol is starting to go off (something that happens all too quickly these day) the car starts and runs rough until the engine has warmed up. The heat of the engine must aid the fuel to fire properly once it is on the turn. This is with super unleaded, as that is the only fuel I use in the Mini.



#3 masslaw

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Posted 12 February 2024 - 11:59 PM

The fuel is fresh and it's a daily driver so the fuel doesn't stay too long.  I was wondering if engine heat had anything to do with the issue but it doesn't take very long to run"normally", not enough time to get the temp up very much. Driving two blocks is all it needs.  I was wondering whether the PTC (?) heater in the throttle body has anything to do with it.  But that doesn't make sense if- as I suspect - the rest of the cylinders are getting fuel. Can't be a valve issue.  What about an ignition issue?  But if one plug isn't sparking, why would it resume after a short drive?  I've only replaced one of the vacuum hoses with silicon ones but don't suspect any of the original ones left.  Replacing the other three is next on the list.  Really concerned that the initial rough running is harmful to the engine.



#4 Jarvis_SPI

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Posted 13 February 2024 - 08:14 AM

I would suggest time to get the fault code reader on it....https://www.theminif...pi-code-reader/



#5 MatthewsDad

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Posted 13 February 2024 - 11:05 AM

Have you tried the Rover Mems reader? It's available as a phone app. Just plug and play (with correct lead). You'll get some real time data that maybe will point to what's happening as your engine warms up.

#6 R32Egor

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Posted 13 February 2024 - 02:18 PM

I just saw where you are located! And your temperatures right now are about -7°C in the day and down to -20°C at night at the moment! Correct?

I presume the car is in a garage at night?

Are you driving it in that temperature?

 

If so then it could be something to do with the PFC Heater



#7 masslaw

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Posted 13 February 2024 - 03:14 PM

I tried to edit my location but can't figure out how to do it.  Moved about a year ago to Victoria, British Columbia where the temps are much more reasonable.  It's -10 there but  +6 here.  We've has one 10-second snowfall.  It's not garaged. 



#8 FlyingScot

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Posted 16 February 2024 - 08:41 PM

Is the temperature gauge working correctly ? Could be a duff sensor or more likely PTC (manifold heater) or the wiring to it (since its around the exhaust is goes brittle and breaks inside). Also check the MFU (relay pack) is actually powering the PTC.

 

Your location is now correct (not sure if the car club is still the same)

 

FS






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