i have noticed since i bought my mk2.5 that it tends to “pink” in 4th gear under load, ie. going a bit slow or up a hill. doesn’t seem to pink in the other gears but i haven’t really tried to provoke it.
Apart from the noticeable noise will it do any harm? Is there anything I can do to cure it?
thx!
Check the timing, the grade of petrol and that you change down earlier to avoid labouring the engine.
Yes, pinking can cause damage.
will check the timing when the weather permits, i use esso standard stuff generally, or occasionally murco. I drive about 300 miles a week so can’t really justify the expensive good stuff!
Does the mk2/mk2.5 have a knock sensor? if so would this stop pinking from happening when working normally?
Esso standard 95 octane?
yep thats the stuff, pretty much 75% of the time anyway.
Yes, it has a knock sensor which should stop engine knock. They are very reliable but will generate a fault code if a fault is detected.
ah right, will have to borrow a fault code reader at some point i guess. Although if the knock sensor was gone i wonder if it would knock/pink through all the gears?
Yes, and it should put the MIL on. Are you sure it is pinking? There is/was an issue with syncro chatter, can’t remember the full details on that off the top of my head but it was more noticeable under light load going up a slight incline.
i’m fairly sure, the noise happens in time with accelerating and grows more noticeable the harder i put my foot down. it drops off at a certain point speed/rev wise. I think if it was something rattling it’d be more constant…not sure on syncro chatter,thats a new one on me.
I attempted to conduct a bit of a test on it this morning on the drive to work. Doesn’t seem to pink when cold, but was after about 30 mins of driving, but only in 4th, changing up to 5th or down to 3rd made it disappear, and it would only pink going up an incline or labouring the engine, pinking progessively getting louder as i gave it more throttle, lifting off made the noise recede.
any ideas? 
In the short term i’m thinking a few doses of redex and changing the plugs maybe might help?
Agreed. It might be a partially clogged injector, so that’s where I’d start - check the plugs to see whether one is in worse condition than the others, and give it a good dose of injector cleaner.
update- still got the pinking unfortunately. a change of plugs and few doses of redex haven’t had any effect… any ideas anyone?
If it is pinking under load in 4th gear then I do not understand how it would improve by changing up to 5th, it should be worse. It is unusual for “modern” engines to pink, are you positive it is not a vibration noise set up by labouring. Best not to labour an engine anyway really.
yeah tell me about it, i had a mk4 astra that pinked aswell, my bad luck i suppose. I’m pretty sure it’s not vibration as it’s directly tied into the amount of throttle i apply, it fades in, and comes on stronger if i put my foot to the floor.
It’s not like i’m labouring it hugely, it pinks around 3000-3500 rpm in 4th gear when the engines warm.
who knows?!
If it is pre-ignition (pinking), it has to be ignition timing too advanced, or, in the old days it could have been a carbon build up in the cylinder head glowing and igniting the fuel on compression too early.
You could have the ignition timing checked with a timing light, E Z P Z.
if the ignition timing is controlled by the ecu and monitored by a knock sensor it is automatically adjusted no? i was under the impression that you can only adjust the timing on older (mk1) mx5s.
just a thought, could it be the fuel filter is naffed?
The 2.5’s like ours have adjustment on the back of the cam shaft. ECU and knock sensor can only do so much.
thanks, good to know!
I now doubt my words. Sorry ,but I’ve been reading re. timing not noticing they were talking about Mk1’s. I’ve sent a p.m. to Roadster Robbie to get the definitive answer. I’m away with no internet for 10 days, when I return I’ll post any new info…
Cheers, Marpar.