A buddy of mine has a 94 with the 4 cyl. SOHC. A manual transmission and about 130K on the odometer. In higher gear at higher speeds he has started noticing what sounds like typical detonation.The sound has become more noticable in recent months but definitely isn't detonating to the point where the engine loses serious power. When he runs 93 octane the sound goes away and comes back with 87 octane. Anyone else have the same stuff going on? Is this common for this year/engine combination? Any help would be greatly appreciated.

 

has he changed the plugs and wires recently, or when was the last time he did

 

Changed plugs and wires at the same time about 5-6 months ago which based on his driving is probably about 10,000 miles. I checked the plugs to see that they were the correct type and cleaned and gapped them. Still happens.

 

sounds like carbon build up. Some guys on here swear by seafoam to clean it out. Maybe one of them will post with the procedure, as I have not used it myself.

 

seafoam works but leaves camel snot in your tail pipe if the carbon buildup is that bad.

 

i would try seafoam i dont know how to use it but everyone says it works wonders
my engine was knockinso i just built it...ha