sounds like a knock sensor is service light on
The knock sensor is located under the intake manifold on the passenger side of the engine. It can be accessed from under the vehicle. Look above and to the slight left of the oil filter on the back of the engine. The knock sensor will resemble a small battery terminal with a bolt through to the engine.
Added info to question: Vacuum also coincidently went from steady 20psi to 15psi/knock - small backfire/miss on acceleration from idle. Knock is steady at idle.
Honda makes the quietest small engine. And be prepared to pay big $ for them too.
I have one question for you: how is a 350 in a 1998 GMC not a small block??
The Knock Sensor (KS) is mounted on the engine, above the alternator and used to sense engine detonation. The knock sensor is a frequency amplifier with the sensor designed to resonate at approximately the same frequency as the engine knock. This allows relatively large signals to be sent to the Electronic Control Assembly (ECA) without electrical amplification and with a relatively small sensor. The ECA uses this information to alter the ignition timing to optimize ignition timing while reducing the occurrence of spark detonation.
I own an 02 Highlander, and sometimes I get a knock when engine is under load, like going up a hill or when accelerating. This is engine knock caused by low octane gas. When I use a mid grade or premium octane, I do not get the sound at all. .
Something is contacting in the engine, my guess is the fan. Have someone sit in your car and accelerate for you and look around to see if you can find anything hitting. If not, take it to someone.
usually on the side of the engine by the crankshaft. The knock sensor provides the computer the position of the crank shaft to give it the right information to get correct timing. A bad knock sensor will cause it to run ruff or not at all The knock sensor senses spark knock or pinging and sends that info to the ecm. The ecm then in turn retards the timing until the ping stops. You can test the knock sensor with the engine running, with a timing light attached watch the timing marks as you tap the engine block with a small hammer, you will see the timing retard briefly.
Ah, the anti-knock sensor on your 1992 Toyota pickup with a V6 engine is located near the engine block. It's a small, important part that helps prevent engine knocking and keeps things running smoothly. Just take your time, be gentle, and you'll find it nestled in there, doing its job to keep your truck happy and healthy.
The Knock Sensor (KS) is mounted on the engine, above the alternator and used to sense engine detonation. The knock sensor is a frequency amplifier with the sensor designed to resonate at approximately the same frequency as the engine knock. This allows relatively large signals to be sent to the Electronic Control Assembly (ECA) without electrical amplification and with a relatively small sensor. The ECA uses this information to alter the ignition timing to optimize ignition timing while reducing the occurrence of spark detonation.
The Knock Sensor (KS) is mounted on the engine, above the alternator and used to sense engine detonation. The knock sensor is a frequency amplifier with the sensor designed to resonate at approximately the same frequency as the engine knock. This allows relatively large signals to be sent to the Electronic Control Assembly (ECA) without electrical amplification and with a relatively small sensor. The ECA uses this information to alter the ignition timing to optimize ignition timing while reducing the occurrence of spark detonation.