C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Error code 43... knock sensor?

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Old Jun 28, 2006 | 03:53 PM
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vander
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Default Error code 43... knock sensor?

Hi all. I have a 1985 and occasionally when i give it gas, it will make a banging/knocking noise between 1800 and 2400 rpms then the check engine light will come on. When i used the paper clip to get the codes, it flashed code 43. According to what i have read this means Knock sensor circuit- Check ECM wiring. Replace knock sensor.

What is a knock sensor?
Why is my engine making that noise?

Thanks. -joe
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Old Jun 28, 2006 | 05:45 PM
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St. Jude Donor '10-'11-'12-'13
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Knock is the sound you are hearing when you hit the throttle. It can be caused by a number of things (very lean condition, incorrect timing, poor fuel quality, poor fuel delivery, etc). Either way, it is not good. There was a thread not too long ago that had some good info about knock vs detonation vs pre-ignition, etc.

The knock sensor is a "listening" sensor that is screwed into the engine block, just forward of the starter. It detects that sound you are hearing and relays the information to the computer (ECM). The computer will then retard the ignition timing until it no longer "hears" knock, but there is a limit to that (set in the PROM).

If it just started doing this and you didn't mess with the timing, it is probably a fuel issue. Bad gas? Clogged filter?
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Old Jun 28, 2006 | 09:35 PM
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ok, so step one, replace the fuel filter. what difficultly level am i looking at?
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Old Jun 28, 2006 | 10:04 PM
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Fuel filter replacement is fairly simple, though you'll need to get the car up on ramps or jack stands. The FSM (Factory Service Manual) details this procedure. You can order one from www.helminc.com. If you plan on doing your own work to the car, it is a great investment. The Haynes or Chiltons manuals don't have the trouble shooting charts or the level of detail that the FSM has.

A fuel filter change is always a good idea, especially if it hasn't been done in a while. A fuel pressure check would also be in order, but that requires a guage and (to do it safely) a passenger in the car to monitor the pressure during acceleration.

Pulling and analyzing a spark plug or two will also tell you a lot about how the engine is running.
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Old Jun 29, 2006 | 08:04 PM
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Originally Posted by byebyeL98
Pulling and analyzing a spark plug or two will also tell you a lot about how the engine is running.
Spark plugs are like the dipsticks of the combustion chambers. Look at the plugs and in a helms manual you will see a chart (with pics) of what it tells you.

If you are not well versed in working on vehicles, find someone near you that will help. This will allow you to learn from them.

GL,
Scott
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