After getting to know my 98 GT 5 spd a little more I have noticed some pretty heavy pre ignition when accelerating hard in any gear especially in 3rd-4th-5th at WOT. Maybe I am wrong but the specs call for regular 87 octane fuel right? That's all I run is the 87. Truthfully as much as it pings I'm not sure the fuel alone would cause it. Any suggestions?

 

well, have you given it a complete tune up yet? plugs, wires, fuel filter, air filter and pcv valve? and a round of seafoaming?

how many miles on it?

 

im not an expert here but i do know that mustangs (fords in general) are known for pinging with middle of the line 87. Both my 98 F-150 and my 03 GT will ping a little when taking off but its hardly noticable (only when slowly backing up driveway). Anyway it seems to go away when i put Chevron gas in it...maybe you should try that...good luck ~ garrett

 

Plugs and wires brand new as is the air filter. I can't see a fuel filter causing a pinging although that will be changed soon too. It will not ping if driven like a normal car but once you twist it's tail it starts. The beast has 167000 miles on it and is bone stock. Thanks.

 

Any other suggestions? I'm going to fill up the next tank with higher octane and see what it does. I have seen mention of running a 180 t-stat but am not sure why some do that. Any relation to pinging? If it isn't too hot this weekend I'm going to fart around with it and see what I can figure out.

 

my 98 would do that on 87, but it stopped with a set of 9mm plug wires, i didn't feel like spending any more money on fuel when its 3 bux a gallon, i also can get over 24 miles to the gallon with a little bit of a lead foot.

 

With that many miles on it you should try a tank of 93 octane. This usually helps higher mileage, carbon built up motors, good luck.

 

I run 89 octane at times, it depends upon the mix of fuel. The car should run fine on 87, it's designed with a quiick-burn combustion chamber made to run optimal on 87, but are we always getting 87? Some gasoline brands from my experience don't deliver a true 87, and as a result my car pings. try different brands or in a worst case run 89. As mentioned, de-carburizing, and tune are also something to look into as well, especially due to the age of your car. My car has 18K miles and seldom pings on 87. You shouldn't have to run hi-test, because the engine is not designed for it, it may even decrease performance and idle.

John