I have a 1992 Ford Escort and it had a spark knock whenever the car was hot and it died on me on the highway. I have not been able to get it to start since. I was wondering if there is any chance that I didn't burn a piston or damage a rod bearing. I heard that octane fuel will cure spark knock. However I am not sure if it will cure it after the car has already quit. I wanted to see someone else's opinion before I tried to drain the lines and replace the gas with a higher octane gas. Thanks. Also the car turns over a little sluggish, but all the belts move.
Also here is an example of the spark knock sound my car was making. It died trying to make it up a steep hill.
YouTube - Spark Knock

EGR is designed to reduce combustion chamber temperature. If not working properly, spark knock will occur.
A compression check needs to be performed while spinning it over. Higher elevated compression readings would mean heavy carbon deposits in the chambers and they act as a sponge to soak up unburnt gasoline causing a very lean burn.
Low readings would mean engine damage like a hole in the piston or burnt valve.
How hot did it get? Forget the octane boost, you have some red flags here and some basic diagnosis should find it.

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Originally Posted by kitch428

EGR is designed to reduce combustion chamber temperature. If not working properly, spark knock will occur.
A compression check needs to be performed while spinning it over. Higher elevated compression readings would mean heavy carbon deposits in the chambers and they act as a sponge to soak up unburnt gasoline causing a very lean burn.
Low readings would mean engine damage like a hole in the piston or burnt valve.
How hot did it get?? Forget the octane boost, you have some red flags here and some basic diagnosis should find it.

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The temperature gauge stayed normal the whole time but when the car died I could see mild smoke coming from the hood and the smell of oil burning. What would I use to perform a compression check

How to perform a compression test
When diagnosing an engine to see what's wrong with it, or checking an engine to see if it's in good shape, often the first step a mechanic will take is to perform a compression test on it. A compression test is relatively quick and simple to do, and doesn't require any tools except for a socket wrench, a jumper cable, and the actual compression gauge itself, which is generally fairly cheap (they run from $20 to $40). It provides a pretty good picture of how well the engine is performing, and if there's something wrong with it, exactly what *is* wrong. Of course it can't diagnose every possible engine fault, but for a test that only takes a few minutes of time and a little gauge for equipment, it provides a remarkable amount of information about the state an engine is in.

What to look for in a compression gauge

A compression gauge with threads on it, which screws into the hole, is preferable (rather than the kind which you simply hold in the hole with your hand). Make sure it matches the size of your spark plug tubes, and that its pressure range goes up to the normal compression level for your model of car.

To perform a compression test:

1. Remove all the spark plugs from the car. (You don't just take out the spark plug in the cylinder you're testing; The test is actually performed with all the plugs out of the car.)

2. Remove the wire which leads from the center of the distributor cap. That's the cap where all the spark plug wires go; The spark plug wires form a circle around the rim of the distributor cap, and then there's another wire in the center of the cap which goes to the ignition coil. Remove that one; Don't unplug the end of the wire that goes to the coil, just take off the end that plugs into the distributor. Ground this wire by connecting the tip of it to one end of a jumper cable, and the other end of the jumper cable on the engine block.

3. If your car has EFI (electronic fuel injection), pull the fuse for the EFI system to disable it while the test is being done.

4. Install the compression gauge in the spark plug hole of the cylinder you'll be testing.

5. Hold the throttle open as far as it will go. The throttle cable is the cable which gets pulled by the gas pedal; Hold open the throttle arm as if someone were pushing the gas pedal to the floor. Keep the throttle fully open while the test is being performed.

6. Have somebody crank the engine several times. As the engine is cranking, watch the compression gauge for a reading. Write down the compression level.

7. Repeat for each cylinder of the engine.

Now you have approximate compression readings for each of your cylinders. Compare them against the "normal" reading for your car in the repair manual. (You do have a repair manual for your model of car, don't you?) Although your readings should be at or close to the readings in the manual, it's actually more important that your readings for each cylinder be close to each other than that they match the manual exactly. If there's a significant variance in the readings (more than 10 or 20 psi), it usually indicates a problem somewhere in the cylinder block, head, or valves. Also look at how quickly the compression rises; It's normal for compression to be low at first, but it should quickly shoot up to the normal level. If the compression increases slowly with each crank, this usually indicates worn piston rings, which are a real pain to change because it requires rebuilding the whole engine.

. . Spark Knock (Detonation)

Spark Knock is a knocking, rattling or pinging noise that may be heard when he engine is accelerating or is working hard under load (driving up a hill, towing a trailer, passing on the highway, etc.). Spark knock means the fuel is detonating.

Detonation is when the fuel explodes erratically instead of burning smoothly. It occurs when there is too much heat and compression in the combustion chamber. It is similar to preignition, but preignition is when the fuel ignites before the spark occurs because of a hot spot inside the combustion chamber. Preignition can burn a hole right through the top of a piston (see photo above).

Detonation is very bad for your engine because over a long period it may cause the head gasket to fail, the rings to break, piston lands to crack and/or rod bearing damage.

CAUSES OF SPARK KNOCK

The things that usually cause spark knock (detonation) are:

(1) The EGR valve that is not working. The EGR valve is supposed to open when the engine is accelerating or lugging under a load. This allows intake vacuum to suck some exhaust in through the EGR valve to dilute the air/fuel mixture slightly. This lowers combustion temperatures and prevents knock. Inspect the operation of the EGR valve, and check for a buildup of carbon deposits on the valve pintle or valve port that may be blocking the flow of exhaust back into the engine. Clean off the carbon deposits with a wire brush and carburetor cleaner, or replace the EGR valve if it is defective.

(2) A bad knock sensor. Your engine has a knock sensor that should detect detonation and tell the computer to retard the ignition timing. If your engine requires premium grade fuel, but you are using regular or mid-grade fuel, the knock sensor should detect any detonation that may occur when the engine is working hard under a load and cause the PCM to retard timing. This reduces power a bit but protects your engine against detonation. However, if the knock sensor is not working, spark timing will not retard when it should. Consequently, you may hear a pinging or rattling sound (spark knock) when accelerating, driving up a hill, or when the engine is lugging under a heavy load.

The knock sensor can be tested by tapping on the engine near the sensor (not the sensor itself) with a wrench while watching spark timing and/or knock sensor input on a scan tool to see if it sends a timing retard signal.

NOTE: Overadvanted ignition timing can also cause the same thing (spark knock). But on most late model engines, ignition timing is not adjustable and is controlled by the engine computer. The only way to change the timing advance would be to flash reprogram the PCM.

(3) Excessive carbon buildup in the combustion chambers and on the tops of the pistons. This is usually more of an issue with older, high mileage engines or vehicles that are only driven for short trips and never fully warm up. Treating the engine with a dose of top cleaner or a fuel system additive that also removes carbon from the combustion chamber can usually clears this up. Some repair shops use a machine called a MotorVac to perform an engine carbon cleaning procedure. The machine uses a concentrated detergent to flush out the fuel injection system and combustion chambers.

(4) Compression ratio too high. If an engine has been rebuilt and the cylinders have been bored to oversize, it will increase the engine's static compression ratio. Or, if the cylinder head has been resurfaced to restore flatness, this will reduce the volume of the combustion chamber and also increase the engine's static compression ratio. These changes will increase engine power, but also the risk of detonation on regular 87 octane fuel. Such modifications may require using higher octane 89 or 93 octane premium fuel and/or retarding spark timing. Engines that are supercharged or turbocharged are also at much higher risk of detonation because the forced air induction system increases compression. This usually requires using premium fuel.

(5) Cheap gas. Regular grade gasoline is supposed to have an octane rating of 87. If the gas station or their refiner is cutting corners and the fuel is not 87, it may knock. The fix for this is to try a tank of mid-range or premium gasoline. Be warned, though, that some stations cheat on this too, and don't always give you the octane rating claimed on the pump. Premium costs more, but may be required to reduce the knocking. Or, if you always buy gas at the same gas station, try a different gas station. Don't buy the cheapest gas you can find. BP, Shell and Mobil are all good brands.

(6) Engine overheating. If the engine is running too hot because of low coolant, a cooling fan that isn't working, a plugged radiator, bad water pump, sticking thermostat, etc. it may cause the fuel to detonate.