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Posted: 29 Jul 2014, 23:15
1.9 petrol been running great for 6 months, just started pinking slightly this week and I wondered why? Could be coincidence, but it happened the first time I put max load uphill in 4th after filling up with petrol at a different petrol station (Esso). Could it be a bad batch of fuel?
Posted: 30 Jul 2014, 05:23
Change of octane rating, ambient air temperature etc all play a part in igniting the fuel at the right moment. I used to get it with Beetles in very hot weather - sounds like small chains being dragged underneath the vehicle. You could always retard the timing just slightly to compensate I suppose. Certainly the best way to tune older engines (particularly those with points) was to adjust the timing until it would just begin to pink under load then back it off until this stops and you'd have almost perfect timing. Engines without timing marks were often tuned that way.
You could fill up elsewhere, the problem go away and you draw the conclusion that it was the petrol when in fact it was a fairly hot day with the vehicle under load. Conversely - it could be a change in fuel source.
Posted: 30 Jul 2014, 07:52
Petrol is a 'Coctail' of ingredients, the quality and octane varies between brands despite all complying with strict standards . If this is the first time you have heard 'pinking' then I would say the change in 'supply is the most likely cause.
Posted: 01 Aug 2014, 14:02
Thanks guys. I presume its not a huge problem, or indicative of something more sinister, as I am just off on hols next couple of weeks.
Posted: 01 Aug 2014, 23:17
Nope. If it does persist you may just need to nudge the dizzy round a very tiny fraction so it doesn't pink (mark it first ofcourse) but I suspect it will just vanish on its own.
Posted: 03 Aug 2014, 08:16
May I add that when it is pinking, damage to pistons can result, so try and avoid it happening. If this were I, I would pop along to the nearest garage that sells two different grades of petrol and put some higher grade (octane) stuff in, to "top up" the octane grade you (may) now have in there. Most filling stations (that offer it) call it "Premium grade" and the higher octane rating is shown on the pump.
Slight aside :- I always use (when available) the higher octane ("premium") petrol. It is a bit dearer, but I swear I get better MPG which compensates for the higher price and the van runs better on it (as does the Scirocco and the BSA motorbike). Mind you, the van runs on LPG 90% of the time
Posted: 03 Aug 2014, 09:08
Its almost impossible to make a DG pink just by changing fuel.. unless there is a problem with the fuel.. (as suggested put some higher grade of fuel in) or a problem with ignition system...
I would go back to basics and check the timing etc and ensure nothing else is going on.. Sure its pinking???
Full throttle up a hill in 4th.. what speed??
heavy camper trying to hold up a hill in top gear is never a good recipe.. change down and allow the engine to "breathe".. they are happier spinning a 3500 rpm than loaded at 2000....