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Discussion Starter · #1 ·
I have this wierd grindng noise now at high RPM's, I think it's my clutch, it's being replaced in 3 days so not sure..also I have a rattling noise at high fuel flow, not necessarily high RPM's, but the more gas, the louder the rattling...it's been to 3 shops, they don't know, ck'd for leaks, nothing, new cap, plugs, wires, filters, not replaced fuel injectors yet, am getting my o2 sensr replaced too cause it idles like hell...anyways...any info would be much apprecated, as this seems to go away, then get worse...I am the second owner, the 1st guy did no maint, but I do everything, timing belt, oil, filters, etc....
 
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Discussion Starter · #3 ·
there is no dealer, but I do have a shop, what is it, cause we can't figure it out, please tell me so I can have it fixed...
 

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maitaru said:
I have this wierd grindng noise now at high RPM's, I think it's my clutch, it's being replaced in 3 days so not sure..also I have a rattling noise at high fuel flow, not necessarily high RPM's, but the more gas, the louder the rattling...
Hmm. On the surface, this doesn't sound good. If you hear a "rattling" (would "knocking" better describe it?) that varies in intensity with engine load, you might be talking about something as serious as a spun rod bearing or it may be as simple as spark knock (detonation.)

Is the "rattling" a pronounced mechanical "knock" that sounds like someone is hitting the crankcase from inside with a hammer? Do you hear it at idle? Can you isolate the rattling to the top or bottom of the motor (i.e. is it louder from from under the hood or if you listen underneath the car)?

Have you noticed any change in power output? Does the temperature gauge show any indication of overheating? I'll assume the oil level is okay, but you might want to have the oil pressure checked out.

If you can describe the sounds a bit more, it might help with suggestions. Also, what engine is this?
 
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Discussion Starter · #5 ·
it's a 95 4 cyl MTX, the oil pressure's been checked, and it comes from the top, not at idle, only while going and when I push the pedal down past my vehicles point of current aceleration. I did notice that in cold climates (20 F and below) the knocking goes away. I originally thought it was a fuel injector not giving fuel to my vehicle(as I understand it we have 2?) but they actualy checked out fine. I don't think it' pre detonation, cause I had the cap, rotors, plugs, wires installed by a shop, thinking I did a bad job of gapping them, and I tried changing plugs, everything...no overheating, ever, no power drop unless I use cheap gas, then it's a little bit worse(the knocking)...I am going to try getting my engine cleaned out....at a shop...they put this stuff in there, hook it up to an air compressor, and blow it out.dunno too much about it, several of my friends have suggested it.
 

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maitaru said:
it's a 95 4 cyl MTX, the oil pressure's been checked, and it comes from the top, not at idle, only while going and when I push the pedal down past my vehicles point of current aceleration. I did notice that in cold climates (20 F and below) the knocking goes away. I originally thought it was a fuel injector not giving fuel to my vehicle(as I understand it we have 2?) but they actualy checked out fine. I don't think it' pre detonation, cause I had the cap, rotors, plugs, wires installed by a shop, thinking I did a bad job of gapping them, and I tried changing plugs, everything...no overheating, ever, no power drop unless I use cheap gas, then it's a little bit worse(the knocking)...
Actually, your car has 4 fuel injectors, one for each cylinder. It really sounds like you are experiencing detonation or possibly pre-ignition. The signs:

- "...when I push the pedal down past my vehicles point of current aceleration" (i.e. lugging)
- "...unless I use cheap gas, then it's a little bit worse(the knocking)"

point to it.

Changing the cap, rotors, plugs and wires won't help if the ignition timing is way off. Have the base ignition timing checked out to see if it's too far advanced.

Some general causes of detonation/pinging:

- spark timing too far advanced.
- lugging the engine (driving in too high a gear for the current vehicle speed) can aggravate detonation. What RPM do you normally shift at?
- defective EGR system. If there's no check engine light, it's still possible the EGR passages are blocked by carbon build-up.
- using low-octane gas. Try a tank of 92 or higher and see how it does.
- excess carbon build-up. Bits of carbon can glow incandescently in the combustion chamber, causing pre-ignition.
- overheating (running too hot increases the likelihood of detonation.
- incorrect heat range on spark plugs
- defective knock sensor

I'd look carefully at the EGR system next if the ignition timing is correct.

I am going to try getting my engine cleaned out....at a shop...they put this stuff in there, hook it up to an air compressor, and blow it out.dunno too much about it, several of my friends have suggested it.
Ask about "decarboning" procedures they might have.
 
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Discussion Starter · #7 ·
I tried the higher octane gas, not much change, it always comes back after awhile...I shift at 3k/4k, that's the other thing, the EGR valve/component, I forgot to check that....where do I get the ignition timing ck'd at? and the knock sensor...I thought those were only in diesel engines....I will ask about "decarboning" procedures...thank you so much...I was really thinking something was gonna blow! I will take it in for the timing and stuff....and will prolly replace the sensors myself...or if you reccommend taking it somewhere I will..I'm pretty good with most stuff on my car as far as replacements, just not as much on trouble shooting...thanx again
 
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