Premium fuel

mmikey82

mmikey82

Well-known user
Jul 17, 2009
2,369
1,527
manchester
From now on i will be using premium fuel only thanks to my local Costco who have put a petrol station at my local store, and sell premium for the same price as normal unleaded at Asda (y)
 
Hi Procomm, I guess Mako's concern is the increased octane level will lead to what used to be called pinking. He may have a point.
Even without a knock sensor you should be able to hear it if it's going on. Sounds more like a rattle than a knock. usually on acceleration, at part throttle in particular. The fuel pre detonates before the spark has fired, before the the engine is at the appropriate point in its stroke, too early and you can be igniting the fuel too far in advance of the piston reaching TDC and reducing power output, not to mention the risk of a holed piston as the excess heat cannot escape as the valves are closed. In the good old days it was a sign that your ignition timing was out. Frankly I'm not sure if it's possible to adjust this on the cougar. I believe the timing is now controlled by Anti Knock sensors and similar sensors inputting to the ECU.
And please forgive me if I'm telling you what you already know.
 
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I did a test a while back only using BP Ultimate 97 octane for about a month..near the end I was getting an overrun pop.

Now only using standard 95 and not getting this issue..although I did force the IMRC open at the same time I switched so that could have caused it rather than the fuel.

In terms of extra miles per tank I didnt notice any difference
 
mabo said:
Hi Procomm, I guess Mako's concern is the increased octane level will lead to what used to be called pinking. He may have a point.
Even without a knock sensor you should be able to hear it if it's going on. Sounds more like a rattle than a knock. usually on acceleration, at part throttle in particular. The fuel pre detonates before the spark has fired, before the the engine is at the appropriate point in its stroke, too wearly and you can be igniting the fuel to far in advance of the piston reaching TDC and reducing power output, not to mention the risk of a holed piston as the excess heat cannot escape as the valves are closed. In the good old days it was a sign that your ignition timing was out. Frankly I'm not sure if it's possible to adjust this on the cougar. I believe the timing is now controlled by Anti Knock sensors and similar sensors inputting to the ECU.
And please forgive me if I'm telling you what you already know.
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your forgiven, there isn't a huge increase in octane between standard 95ron and premium 97-99ron which is why only earlier model c1's had the knock sensor fitted which was precautionary as the car was designed by Mercury to run on the American 85ron it was subsequently found that the likely hood of pinking was so low because of the self tuning of an ecu that the knock sensor was removed
 
err
i thought the reason for higher ron fuel was for high compression or hot engine's which suffer from detonation at tdc when used with lower ron fuels.

this is certainly the case with melina who slightly pinks with normal fuel...this goes when used with ultimate.
have i got this wrong or am i misreading something..

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yea thought so...i googled it:giggle:

https://www.torquecars.com/articles/fuel-octane-ratings.php
 
the bp ultimate diesial(i can't spell the f***** ether:LOL:) makes my transit much faster but oddly the shell vpower dont..

the only issue i do have with running the transit on it is if i go back to normal it runs like an absolute dog for the first 30 or so miles.

melina loves both and i can confirm that the bp ultimate REALLY does keep things clean...
 
Hmmmmm.....when I have used Shell V Power I have heard a small rattle under acceleration, but never really gave it anymore thought. I also get banging and popping when lifting off the accelerator, so sounds as though this is the issue that someone mentioned earlier with the fuel pre-igniting? Or have I got that wrong? Anyway, the small rattle that I have heard many times is still there, even after changing back to Tesco cheap fuel, so have I done damage to the pistons etc? She seems to run ok, never had any issues.
 
TopCat1127 said:
Heat shield Tim
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I thought about that Tony, but it sounds more like it's coming from the engine, rather than through the exhaust. It only lasts a couple of seconds and it's only at certain revs. As far as I know all heat shields are in place and not loose. I've had heat shields loose on other cars but this is a different sort of rattle. I've never really thought too much about it, as, as I said my coug runs really well and never had any issues with her.
 
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