[slingblade05]

first of all what is detonation lol?
and how to fix it lol
1991 mustang

[itschristorres8]

well first off...those are really good questions lol i'd like to know too ..

[DaveT]

usually knocking back timing wll stop detonation also using higher octane gas will help and if the car has knock sensor it should autatically knock back timing to prevent it and if your car has one (I am not usre if it does) it may be bad

[matrixpuba]

right. either pull some timing or use a higher octane number. if you hear what sounds like marbles in a tin can, its detonation. next comes a broken piston lol

[Zak]

lol

[88BlueGT]

+1 Try running a higher octane and see if that helps. If not, than lower your timing and you shouldnt have any problems. What I would do is run 91 octane. Drop your timing to 10 degrees and see if it pings (it definetly shouldnt though). Than work your way up one degree at a time until it starts to ping. As soon as you hear pinging knock it back one degree and set it there. This whole process should take 10 mintues and possibly save your motor.

[interfac9]

What about negative timing? Can it cause detonation too?

[superbean]

Originally Posted by interfac9 What about negative timing? Can it cause detonation too?

if timing was that far out, it would run like total ass and not even get a chance to detonate.

if your car is detonating, and you have a working knock sensor...

1) air fuel is too lean -
Culprits -
Clogged Fuel strainer on the pump
Weak fuel pump
Low voltage to fuel pump
Clogged fuel filter
dirty injector
Fuel pressure low
Fuel leaks
Maf signal is dirty
Maf ground is dirty
vacuum leaks

2)Timing -
Culprits -
Timing too far advanced for octane
Base timing incorrect
Coolant temp sensor malfunction
cam timing incorrect

[interfac9]

any way to test the knock sensor? I have no codes. I run Amoco Ultimate religiously, 93 Octain, wit the SCT Tune backed off 4 degrees in all three ranges. Got on it on an onramp this morning and got marbles... c My 4D has been on me about the pinging for a while, and it comes and goes, an not consistent with new tanks of gas.

[interfac9]

base timing adjustment... How? I don't know the OHC motors.

[ChrisJ]

What plugs you running brotherman and what gap?

[88Saleen]

just wondering what all your guys were running for timing? stock is 10 degrees advanced correct?

[86_Notch]

Originally Posted by slingblade05 first of all what is detonation lol? and how to fix it lol 1991 mustang

add more timing j/k

[interfac9]

Originally Posted by ChrisJ What plugs you running brotherman and what gap?

Last change was to Motorcraft iridiums with stock gap. Usually use copper but figured I would try out the iridiums.

[interfac9]

Originally Posted by 88Saleen just wondering what all your guys were running for timing? stock is 10 degrees advanced correct?

I didn't know stock timing was that advanced on these cars...

[fateisajester]

Detonation is when your fuel is ignited before the piston has reached the end of its up stroke. Just like it sounds, detonation is an explosion in the cylinder, which is bad. A common misconception is that the fuel is supposed to explode to make the engine work. Infact, the engine turns due to an expansion of gas (similar to the way some people air up new tires by lighting eather inside it)

[Hunt_chevs]

i run mine at about 15*advanced

[Chris951]

Change your plugs and set your timing around 12 dude

[interfac9]

Originally Posted by Chris951 Change your plugs and set your timing around 12 dude

Now keep in mind I'm currently using an SCT canned tune.
12* advanced on THAT?