Tap or knock!

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10-20-2002, 06:29 PM

tsefreeflow

I'm Chillin

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Join Date: Oct 2002

Location: Phoenix, AZ

Posts: 194

Tap or knock!

Ok I thought that my car was tapping because of octane but the octane change did not help anything. Does anyone have any idea what would cause a tapping or light knocking noise at only 4000 RPM +- 500 RPM? I put 91 octane and boosted it up to 100+ and now left it at 91, did nothing, put in MMO and did nothing. Could maybe a loose rocker do that? I always thought if that was the case it would knock all of the time? anyway I am at my wits end on this one.

1990 300zx NA (beautiful first year)
1980 Triumph Spitfire (last year)

10-23-2002, 10:48 AM

tsefreeflow

I'm Chillin

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Join Date: Oct 2002

Location: Phoenix, AZ

Posts: 194

Re: Tap or knock!

can anyone help me here?

1990 300zx NA (beautiful first year)
1980 Triumph Spitfire (last year)

10-24-2002, 03:40 PM

L0ki

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Re: Tap or knock!

possibly a faulty or incorrectly gapped spark plug(s) you tried a new set ?

Rusty Datsun x 3

10-25-2002, 08:10 AM

tsefreeflow

I'm Chillin

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Join Date: Oct 2002

Location: Phoenix, AZ

Posts: 194

Re: Tap or knock!

No I have not tried that yet. I will have to look into that one. Never would guess that would cause the problem though. Thank you!
Could you explain, for my ignorance, how this could cause this to happen?

1990 300zx NA (beautiful first year)
1980 Triumph Spitfire (last year)

10-25-2002, 05:41 PM

L0ki

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Posts: n/a

Re: Tap or knock!

well if the gap was too small then the spark would be too strong and cause it to detonate ....

or maybe a wierd plug ....

are you running a stock engine or do you have a higher compression ?

Rusty Datsun x 3