Hello everyone:

My question is that I sometimes hear a knocking ( valves sound, don't exactly know) that happens when going uphill but the thing is that it does this like 1 in a 1,000?

This is what I've found on that matter:
Knocking happens because as you compress air, the temperature of the air increases. The temperature may increase enough to ignite the fuel before the spark plug fires. Source:HSW (http://auto.howstuffworks.com)

In the car manual it reads that the recommended octane is 87 but I think is 89. Also that only happened when I used Exxon 87, I then tried again Gulf 87 the Knocking went away I think the fuel quality has lots to do. :grinyes:

Escort LX 97 US
PS. I sometimes(1 in a million) hear it does it but last like .050 sec. and the sound is very fainth. I think I answered to myself, but suggestions are welcome.

I've got an 88GL and it knocks (always has since new) when going uphill using regular 87 octane gas. I've always had to use mid-grade to keep it from knocking. I reckon that the problem is easily solved by spending a few extra cents per gallon.

Hello everyone:

My question is that I sometimes hear a knocking ( valves sound, don't exactly know) that happens when going uphill but the thing is that it does this like 1 in a 1,000?

This is what I've found on that matter:
Knocking happens because as you compress air, the temperature of the air increases. The temperature may increase enough to ignite the fuel before the spark plug fires. Source:HSW (http://auto.howstuffworks.com)

In the car manual it reads that the recommended octane is 87 but I think is 89. Also that only happened when I used Exxon 87, I then tried again Gulf 87 the Knocking went away I think the fuel quality has lots to do. :grinyes:

Escort LX 97 US
PS. I sometimes(1 in a million) hear it does it but last like .050 sec. and the sound is very fainth. I think I answered to myself, but suggestions are welcome.


How stuff works is a pretty good site for general automotive info. Here's another pretty good description of what octane rating is and why it matters.

3DAuto (http://3dauto.com/viewterm/183/1/)

and also a pretty good description of detonation and some of the other related terms, concepts etc.. Hope that helps.

3DAuto (http://3dauto.com/viewterm/2568/1/)

On the older cars they will knock if the timing is off. Newer Escorts do not have adjustable timing.