buzz12586

After my car has warmed up for a while and I accelerate kinda hard I hear this loud pinging noise that almost sounds like a diesel and then my check engine light will come on. I checked the codes and I got 42 and 43 which have to do with the EST. As soon as the light comes on the knocking stops. My friends dad said that my knock sensor could have gone bad. Where is this located and how hard is it to replace?

aklim

KS going bad is one option. The other is that the KS connector is bad. They are hard to do from the top so you will need to go from below. This is a single sensor wire with the end that looks like the one for the fan switch except the fan one is in the head and this is in the block. I chased a bad KS and kept getting codes till I changed that connector. Supposedly the KS usually is bad if it leaks.

Now, this KS, unlike some others runs into the water jacket in the block. This means that when you unscrew it, coolant will come out. DO NOT TO THIS WHILE THE ENGINE IS HOT OR EVEN WARM. You will not like what happens when you pull that sensor and the coolant is hot. You need to make sure the radiator cap is on so the coolant doesn't come out as fast as if it were not. If you are quick, the loss of coolant is minimal but some splashing is definately in the cards.

buzz12586

So the fan switch is in the head??? No wonder the new one I bought didn't fit. I am dumb. Thanx for the help.

aklim

On the drive side between exhaust ports 1 & 3 is a sensor. That is your temp sensor. On the pass side betwen cylinders 6 & 8 is the fan switch if you have 2 fans. The plug to the KS looks just like the fan switch plug except it is NOT on the head but on the block and probably in the middle.

aklim

I wonder if you have other issues because even without the KS, should you be hearing that kind of knocking you describe? How is your idle oil pressure? How is your compression? Do your plugs exhibit a tan color or are they varying in color? What compression and what octane gas are you using?

buzz12586

My idle oil pressure is fine. I am not sure about compression or the plugs. I am about the change the plugs though cuz I don't know the last time they were changed. I am running 87 octane.

aklim

Plugs should all look alike in condition. A tan color is a good sign. You could run a compression test with a test gauge. Also change fuel filter and see if that changes anything. What sort of engine? Any mods? You might have to go up in octane.

How many psi at warm idle? Too low and you might have worn bearings.

buzz12586

Engine is a 305 TBI mods are in sig. It is about 15 psi at idle.

1fastformula

Did you break down and buy the premium like I told ya????? Look familiar??
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Originally posted by 90rocz
Sounds like an "ignition timing" or a "lean condition" rattle, either caused by overheating, or clogged fuel filter, dying fuel pump etc...If you can pull up the codes by using the Assebly Line Diagnostic Link (ALDL) it will be really helpful...You used to be able to get little aluminum keys with instructions from Autozone just for this..
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Definately Pinging.....I hope you are running 92+ octane fuel. If so you need to check your timing. Might need to back it down. My ole' L98 di the same thing. I accelerated and the pinging started then all of a sudden Check light comes on. Good news is that if you reset computer, your car should run like it did.

PINGING!!!!!

Later


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Just try it...5 gallons at least and run it. TRUST ME ON THIS!!!! My '87 carbed did the same thing and when I went to 93, all was good!!!!

Think of it this way....It is alot cheaper and easier to change fuel to see than to go about changiong everythnig else

Later

aklim

One way to tell is to run the car almost empty and dump in a few gallons of race gas. If it pings then, you have a problem. When my old motor was going out, I could not hear it but the KS picked up a lot of knocking. Race gas didn't do anything but thicker oil helped keep it down. That was how we knew the engine was going south. Compression also was uneven and oil pressure was low, about 20 psi. Now idle warm with 0W30 Mobil1 is about 27-33 psi depending on weather.

buzz12586

I checked my timing and it is at 0* which it is supposed to be. I may try running higher gas just to see if that stops it but I don't see why it would all the sudden start doing this. I think that the EST works because when we checked the timing I left it connected the first time and the timing was advanced, then when I took it off the timing was at 0*. Is there any other way to check the EST?

aklim

With the EST disconnected it should be 6 deg advanced.

buzz12586

The sticker under my hood says that for my car the timing should be at 0*. I just put in 89 octane today to see if that fixes the problem. If not I will try a tank at 93. I still don't think I should have to run higher octane though, I think there is another problem. The pinging only occurs once my car has gotten to about 170-180*. Before that there is no pinging at all. And to fix my eariler post my oil pressure at warm idle is about 28 or so.

aklim

I think you want to check around at a dealership because most chevy engines are at 6 deg and the Chilton books and haynes also say 6 deg.

TheGreatJ

Chilton and Haynes are bad about getting their info crossed up. The TPI motors time at 6*BTDC and the TBI305 times at 0*.

You may have excessive carbon buildup on top of the pistons. Run some octane boost and split a can of SeaFoam between the gas tank and the intake plenum (just let it suck it through a vacuum line.) That should help.