lack of knock sensor, result?

Would a missing/broken knock sensor cause the engine to operate like total poo?

Describe symptoms, please.

The knock sensor has no real result WRT engine performance unless you have serious carbon deposits or are running really crappy fuel - then you'll lose power. Why? Because the knock sensor will generate a signal in the event of preignition/detonation (more the latter,) and will advance timing until the detonation problem goes away (meaning smoother combustion.) The ignition timing will "chase the ball" going back and forth across the knock threshhold, trying to get maximum efficiency and economy while avoiding damaging detonation.

Lacking a knock sensor entirely simply means that the ECU will not be able to detect preignition/detonation, and can eventually result in engine damage (iff you're running crappy fuel for a long time, or don't clean the crud out of your engine...) If everything is working in proper trim, the knock sensor is simply "along for the ride" - it only generates a signal when something goes amiss.

While I agree with 5-90 on the knock sensor, it seems to me that one poster mentioned that when he put a late model short block in his Renix, a block without a provision for a knock sensor boss, he ended up plugging in the knock sensor to the harness and tying it up out of the way. I don't remember if he had reported problems, but that is what he did.

Sounds about how i understood it. i replaced a renix block with a used one and the KS broke (of course). it idles ok but nothing above idle is good. guess ill try something else... thx guys

Wallyman said:

Sounds about how i understood it. i replaced a renix block with a used one and the KS broke (of course). it idles ok but nothing above idle is good. guess ill try something else... thx guys

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Indexing the distributor properly is critical to getting the injection correct. Try moving a tooth or two back and then forward to see if there is any improvement.

5-90 said:

Describe symptoms, please.

the knock sensor will generate a signal in the event of preignition/detonation (more the latter,) and will advance timing until the detonation problem goes away (meaning smoother combustion.) .

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I think you got that backwards 5-90. It retards the timing until the ping or detonation problem goes away.

The lack of a ping sensor can lead the ecu to run with too much advance.

But if you don't have pre-ignition ping, you are OK. If it does knock, try premiun. If it's a knockin, don't go rockin.

old_man said:

I think you got that backwards 5-90. It retards the timing until the ping or detonation problem goes away.

The lack of a ping sensor can lead the ecu to run with too much advance.

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Thanks - I always get those two bollixed up.

To me, "retarding" the timing means firing it later, while "advancing" the timing makes it fire earlier. You'd fire it earlier to get your P-V curve back if you're detonating, and you usually work to fire a bit later than stock to improve the P-V-theta timing (peak pressure resulting in increasing volume at 12*ATDC, to maximise leverage on the crankpin.)

Thanks guys. I got it. Just retarded the timing a notch, PERFECT!

5-90 said:

Thanks - I always get those two bollixed up.

To me, "retarding" the timing means firing it later, while "advancing" the timing makes it fire earlier. You'd fire it earlier to get your P-V curve back if you're detonating, and you usually work to fire a bit later than stock to improve the P-V-theta timing (peak pressure resulting in increasing volume at 12*ATDC, to maximise leverage on the crankpin.)

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Unless we're talking about something different, you retard, that is fire later, to combat detonation.