1994 Chevy K1500 P/U 5.7 liter 350 4X4 5 speed. When the truck is under a hard pull the valves start knocking, the knock sensor adjust the timing and the check engine light comes on. The code for the light is "not detecting knock sensor". I have changed the pcv valve (which was suggested) and no change. This has went on for about 5 years. Doesn't matter the grade of fuel I use. Routine maintance and tune ups have been done to this truck. The converter was taken off 7 years ago because it was clogged. The truck runs rich after the timing adjust. The light resets itself when it is turned off. ( the code is saved)
2007-03-25 15:07:40 · 8 answers · asked by bamafan1550 1 in Cars & Transportation ➔ Maintenance & Repairs
hi, a common misconseption on this noise is the valves are banging or knocking, the noise ur hearing is actually caused by preigntion detonation, in other words, the fire is starting in the hole b4 it is supposed to, the plug has to be the one to start the fire, if there is excessive carbon build up on the piston and or valves it can devolop a "hot spot" and actually start the power stroke prematurally, what i would recommend is getting some type of "induction service" and injector clean, and i am not talking about running a can of stuff thru the gas tank, that stuff works but not good enough, try to find a shop in your area that sells BG products and get a induction service, if u cant find BG find something similiar, there product is very good. that truck and computer was designed to run on 87 octane, another thing that might be causing the knockin is the mass air flow sensor, i would take it to someone and have them look at it.
2007-03-25 15:54:31 · answer #1 · answered by onefast1990stang 1 · 0⤊ 0⤋
Have you checked or replaced the knock sensor? Its not the valves you're hearing, the engine is pinging due to overadvanced ignition timing. If you've futzed with the distributor, put it back where its supposed to be. Then check the sensor and wiring, which is on the side of the engine block. Use spark plugs with one heat range cooler will help the pinging. And you've got to run at least 2 tanks of high octane before you see the effects. Change vacuum lines, fuel and air filters and O2 sensors as well.
2007-03-25 15:25:55 · answer #2 · answered by electron670 3 · 0⤊ 0⤋
out of your description, an oil replace is so as. The knock ought to be incorrect gas octane - too extreme or low. in case you're utilising 87, attempt utilising 89 for a pair of tanks. in case you employ 89 or larger, attempt the decrease octane. A ticking sound that will advance over the years in many situations means a valve adjustment is needed.
2016-12-15 08:51:47 · answer #3 · answered by ? 4 · 0⤊ 0⤋
Excessive carbon build up on the valves may also be causing pre-detonation which the knock sensor will not be able to correct.
If it is a high mileage or a rough service motor it may be time to open it up and see if it's time for a valve job, or possibly a rebuild.
2007-03-25 15:33:24 · answer #4 · answered by konstipashen 5 · 0⤊ 0⤋
disconnect the positive battery terminal for a couple minutes. Other than taking it in to have it reset that is the most generic way to clear it. but it sounds like your timing advance system is not working.
2007-03-25 15:18:48 · answer #5 · answered by Kill_Me_Now! 5 · 0⤊ 0⤋
The wire is broken or the sensor may not work right.
2007-03-25 15:13:32 · answer #6 · answered by Spring loaded horsie 5 · 0⤊ 0⤋
the knock sensor is bad,and not adjusting the timing.
2007-03-25 15:16:03 · answer #7 · answered by Anonymous · 0⤊ 0⤋
It sounds to me like your valve springs have gotten weak over the years.
2007-03-25 15:19:29 · answer #8 · answered by sasyone 5 · 0⤊ 0⤋