Hey guys, Of late I have started to notice a pretty scary sounding rattle when climbing in speed as you pass the 1500rpm point. The noise seems only every to appear on take off so to speak, through first, second and occasinally very faintly in 3rd. And only ever as you speed up slowly, if your up it the noise isn't there. This noise sounds alot like 2 metal plates vibrating against each other, and sounds like it is more towards the back of the engine not sure on location exactly. Has anyone had this, was it major etc
Sounds like detonation..... This is not good, I suggest not driving the car till you get it fixed. It could be as simple as having a batch of bad fuel, but more likely to be afr related (i.e running lean). Check for vacuum leaks.
This noise has been around for some time, have had diagonostics run if that may have picked it up, also have had a mechanic look at it, and their conclusion was just that, a plate rattling up against something. Is there anything else it could be?
i've been noticing this on mine just reccently- mainly in the heat, but i'm thinking it could be exhaust / cats related. Actually gonna climb under this afternoon and see if there's any loose shields (possible around cats or starter motor).
Exhaust ? Could be a heat shield or cats or exhaust touching somewhere. Does it only happen when under load when engine/gearbox will twist a bit ?
Same Issue Sounds like the same sound as mine, still trying to work out what the go with it is accept mine is doing it up until it gets over 2300rpm but then it is fine
I'd say so. I've never known a car to detonate under slow acceleration or low loading. Maybe if you were to high a gear at half to full throttle while it struggles to pick the revs up on regular fuel. Since the noise isn't there when she "ups it" then it sounds nothing like detonation.
Detonation at low revs..... Detonation can occur at low revs/load. If you have a leak, at low revs/load it will suck air (vacuum) which will lean out your mixture. Zeds already run around 15.5 afr's in that region under normal circumstances, so 'leaning out" is easily achieved. When you go WOT the leak now becomes a boost leak which blows air and makes your mixture richer. Add the fact that most fuel maps already dive to afr's of 10 or 11, and you find yourself dumping heaps of excess fuel into the cylinder. Not much chance of detonation with an afr of 9:1
Car won't det. under low load. low revs and high load, yes. Any rev and high load with a lean and/or low octane afr will ping like mad, but as I was trying to point out, she wasn't putting the foot into it. I do understand where you're coming from though.
IceTeazZe did you ever determine what your problem was? I've had an almost identical 'plate rattle' lately but I believe it's more gearbox area related than engine. I'm hoping to have Niall look it over in the next week or two. Shed some light on it for us...
ozjustin or iceTeazZe if yous do find out ur problems please let me know mine is exactly identical 2 everything that has been pointed out and that rattle is really starting 2 piss me off
Well I think IceTeazZe fixed the problem by shearing the front of her Zed clean off with a truck http://www.aus300zx.com/forum/showthread.php?t=286983
mine did that right on 1500 to about 1600rpm, but stopped as soon as it was past there. IB and Zcar91 came around they said it was the VCT, nothing really to worry about, might go away, and it did.
These odd noises can be very misleading sometimes. I had a simialr thing on a Cortina many years ago, a vibration that only occurred at around 2000 revs. Tried everything, the RAA said it was the rad fan out of balance so I replaced it - no difference. Finally found it one day. One of the 3 bolts holding the alternator had sheared off but the head was still holding in the hole so it appeared Ok. Replaced the bolt and vibration gone. Not suggesting this is the cause here but could be something just as obscure.
