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Bone stock car knocking on load

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Old 10-29-14, 10:34 PM
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Originally Posted by Barry Bordes
The stock plugs run a lot of gap. About .060" if I remember right.
I found that a HKS Twinpower was the best addition to a nearly stock (and up to 550 hp) engine.
It is easy for the spark to blow out with boost and a wide gap.

Could the pick-up coils have their plugs reversed?

You might try to decarbonize the rotors... maybe you have a buildup of carbon.
Chevron Techron is a great injector cleaner but also cleans internal carbon buildup.

Also, do people still use Seafoam as a cleaner?

Some thoughts,
Barry
too bad the gap cant be adjusted. but i don't think an all stock car should be having issues regarding plug gap and weak spark. I still dont know how a lack of spark can cause preignition knock.

i dont think i have carbon buildup, because the engine is literally a new replacement from mazda, not a rebuild.

Originally Posted by Dvst8
post a sound clip if you can
I don't particularly like reproducing the sound it makes, it scares the crap out of me.

Originally Posted by dguy
No it isn't. The car wont run with the pickups reversed.
THIS is good to know, i was just about to start digging into the car to check when i read this.

Could a partially clogged stock downpipe cause this? the car seems to lack a lot of power in the top end of the rev range. 5000+.
Old 10-31-14, 12:44 PM
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I've seen people have similar issues with a plugged cat.

Seeing as yours is USDM and has both the pre cat in the downpipe and the second cat it could be that one or both are getting clogged up. Its easy enough to check, or swapping on an after market cat less downpipe never hurts anyway.
Old 10-31-14, 02:16 PM
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Would be nice if you had a PFC and could log the knock. Know anyone who could loan you one for a just cause?
Old 11-01-14, 01:53 AM
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Originally Posted by FD3Cam
I've seen people have similar issues with a plugged cat.

Seeing as yours is USDM and has both the pre cat in the downpipe and the second cat it could be that one or both are getting clogged up. Its easy enough to check, or swapping on an after market cat less downpipe never hurts anyway.
I'll be installing a 3" downpipe in the next week or so. I'm hoping its just that.

Originally Posted by rx7 SE
Would be nice if you had a PFC and could log the knock. Know anyone who could loan you one for a just cause?
I don't know anyone in my area with a power FC. but changing the computer would probably change or mask the issue wouldn't it? especially if the map didnt work with my car.
Old 11-01-14, 08:50 AM
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Originally Posted by Azriel_Strife
I'll be installing a 3" downpipe in the next week or so. I'm hoping its just that.



I don't know anyone in my area with a power FC. but changing the computer would probably change or mask the issue wouldn't it? especially if the map didnt work with my car.
Changing the ecu could do a number of things. But generally when ppl install the PFC a lot of the weird quirks that the rotaries tend to have go away like the 3800 hesitations and such. Also you could pull timing, and log the knock to see if that truly is what you're hearing. If its audible your knock levels would read really high on the PFC.
Old 11-01-14, 02:23 PM
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The plan is go to full stand alone in the spring anyway. Microtech with custom harness and 350rwhp tune with 14-15 psi.

i hope my downpipe cures it in the meantime. i'll also be doing a fuel filter replacement and relocation. and I may check the sock in the tank also, but from what i am reading the sock doesn't cause issues very often at all.
Old 11-02-14, 01:24 AM
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Stock precat is out, man its heavy compared to the stainless one. just gotta get some header wrap so i can put it back in!
Old 11-05-14, 08:07 PM
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Well, i got the new downpipe in, but unfortunately i broke the o2 wire reinstalling it. i'll have to get another o2 sensor..

good news is, i can't hear any knock anymore. and boy did it wake the car up!
Old 11-06-14, 09:37 AM
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Originally Posted by Azriel_Strife
Well, i got the new downpipe in, but unfortunately i broke the o2 wire reinstalling it. i'll have to get another o2 sensor..

good news is, i can't hear any knock anymore. and boy did it wake the car up!
eeeexcellent
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