Pinking can be caused by several things, a lean mix, timing being advanced too far, wrong plugs, carbon deposits or a bad batch of fuel.

If it develops out of the blue I'd try some fresh fuel from a different source from you last filled up - just in case it's a dud batch.

Re. the O2 codes - if (for example) the mix is out then that can throw the O2 sensor out of parameter. What voltage readings is it showing on live data?

 

Thanks Taurus,

I just idled the car on the driveway with a few blips on the throttle to test out the range.

At idle (during warm up) it jumped between about 150 to 750 mV, though mostly hovering in the 600+ mV range.

When I gave it some throttle (hovering around 3500 rpm) the voltage dropped to about 70-150 mV.

Engine temp got to about 90 before I shut it down.

 

Those readings suggest it's running lean - maybe an air leak? Worth checking.

The basic reading ought to switch between Lean/Rich about every second - but a rough guide is 0.2v is lean, 0.8v is rich. It's OK when cold, probably due to the richer mix, but when hot it might be too lean - which would cause pinking of course.

 

Hi Taurus, thanks for your help.

I checked for intake/vac line cracks or loose connections, everything at least seems ok.

Engine bogs badly on cold startup now, but gets better after about 30 seconds. Still getting pinking under load.

I then tried unplugging the MAF sensor and took it for a drive. On a warm engine, it ran considerably better than before. Still some pinking (combustion chamber carbon?) but the car has more power through the revs and doesn't bog.

I then let the engine idle before shutting it off, and alternated between plugging the MAF back in/out/in/out a few times. Every time the MAF was plugged IN, I noticed that the idle quality and engine vibration became noticeably worse and more ragged. When unplugged, it idles very nicely for a 3 pot and the engine vibration seems more consistent.

OPCOM still shows no codes for MAF, but I'm wondering if its already given up the ghost?? There's ~103k miles on the car and the original MAF and I know not to try cleaning them.

 

Well if the MAF dud then that would throw the mix out. Since you suspect it's dead then you've nothing to lose by trying to clean it - spray with carb cleaner and allow to dry thoroughly before refitting. If it fixes it great, if it kills it you're no worse off.

 

Cleaned MAF yesterday, let it dry overnight, refitted this morning. No luck, same terrible running with it plugged in. New Bosch MAF on the way.

Is there any way to check if the knock sensor is working properly? If I let the engine idle and tap the block lightly with a hammer, would that normally trick the ECU to retard the timing when I'm running live data?

 

I literally had exact same issue on my 1.0,

I replaced the Lambda sensor and still same, Then I replaced the MAF sensor and never caused a problem since. Same error codes too.

 

The new MAF came in this morning, plugged it in and cleared the old missing-MAF codes.

I tried giving the car an 'Italian tune up' (driving it very hard at high rpms to hopefully burn out carbon deposits) for about 20 minutes, it runs great overall with no hesitation or flat spots, but still have pinking at low rpms.

When the tank runs low enough I'll have to try a different station to see if petrol quality is an issue.

At least the bogging issue has been resolved.