Knocking (Hello, who's there)

[Escort_LX]

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

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.

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.

[Rainey]

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.

[bmw540]

Originally Posted by Escort_LX

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

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.

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

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

3DAuto

[AzTumbleweed]

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