GS-R knocking

Last summer, my '94 GS-R started having a problem with a very light knock under load at low rpm. The problem has slowly gotten worse in that the knock is noticeably heavier now. Not really a problem - yet
- but it has gone from curiosity to annoyance. The car has 145K of hard use. Generally maintained well but may be coming due for some routine items and about 30K since its last valve adjustment. I use Mobil 1 but I only change it twice a year. Engine all original and stock except for a header to replace the noisy A-pipe. Other than the knock, the engine runs great like always.
Any ideas?
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Try Premium gas.
Check ignition base timing.
Motorvac service to remove deposits from combustion chamber.
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I should have mentioned that I only use premium per Honda reco.

Good idea.

Is there any way to determine if this is needed?
Thanks for the suggestions.
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The first thing that you should do is to adjust the timing--If you have never done this before--have a mechanic do it for you.
If that does not solve the problem, you should have a complete tune-up. Mechanics use a Diagnostic Computerized Engine Tester when performing a tune-up. That means the mechanic can easily find and repair any problems that are the cause of the "knock". When I had a "knock" problem--I solved it by adjusting the timing but there are other causes. Also, attempt to find out whether or not your car has a "knock sensor". If it does have a knock sensor--it might need to be replaced.
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Your GS-R has anti-knock sensors. This means it retards the timings when the car pings. Usually, the computer should throw a engine code when they malfunction, as it's doing in your case. Maybe something else is wrong with your engine? Too much carbon in the intake? worn plugs? cables? distributor cap?

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Nightd00d wrote:

exactly like this myself and had to work it out.... no codes, lights, help from a NG, etc, just crackly acceleration and crappy idle... Dealer couldn't even correct it, although they said, they knew what it was and charged me a lot to "adjust the problem".
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