pre ignition

Z

zee1

Member
 Torquay Devon
Hi all when I was out the other day I went up a hill between two walls and I could here my 2.5 'pinking' I only noticed it when going uphill at fairly low revs maybe 2000- 3000 rpm. My question is why would it be pinking if the ignition etc is all set up from the factory and not adjustable? I have been running it on 97 ron not the cheap 95. Is it possible to use an octane booster? If so which one? Obviously I don't want to damage the cat/ fuel system!!
thanks for your help again,
Steve
 
Pre-ignition is very unlikely on these engines as the sensors should just keep ratcheting back the timing, if it's and M54 (pre-facelift) it's more likely that you are hearing VANOS rattle. Noise alone is not necessarily an issue, but if they get really bad you may have uneven idling, 'soft' pick-up at low rev's and hesitation.
The pre-faclift M54 VANOS had a poor quality material used for the seals which can degrade, according to my indi (ex BMW) good quality oil changed regularly cuts the incidence and they are best left alone unless you actually have rough idle, hesitation or soft pickup. Honest advice IMHO since I had asked him to rebuild mine with upgraded seals as a precaution, but he says it's running spot-on and did not need doing(2003 @46k miles).
 
The car is a 2003 2.5 with 25k on the clock it runs perfectly no uneven tickover and the power delivery is very good. It revs perfectly from low down to high revs. I just happened to hear what I assumed was pinking and thought I would ask on the forum.
thanks for your reply Steve
 
Your initial description Zee1 is exactly what mine used to do on 95 RON. Every tank for the last 2 years has been Shell VPower Nitro 99RON and I've never heard it once since :thumbsup:
 
My e85 2.5 does the same if I use 95 Ron in warmer conditions. Anything higher Ron it is grately reduced or non existant.

Been the same for 10 years so I wouldn’t worry.
 
I have been using 97 ron. I don't have a Shell petrol station close to me to use v power which is why I was asking about and octane booster. Thanks for you replies, Steve
 
Also look out for a Tesco, their premium unleaded supposed to be 99 ron
 
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