i have a 2000 auto gt. sometimes at high rpms right when or before it shifts i hear a metallic rattle in the motor(pedal to the floor between 1st and 2nd gear). my uncles 98 4.6 truck does it too but worse. is this a problem with these motors. what is it. my uncles has been doing it for five years. my car has 60,000 on it now. it does not happen all the time at high rpms. it sounds like spark knock. i use 87 octane and the sound comes from the upper portion of the motor.
rattle spark ping possibly
- Thread starter dastang2
- Start date
Matt's 03 GT
Member
You may try running a test tank of 89 octane. It sounds like detonation and is something you should definetely take care of asap.
You should also check the spark plugs to be sure they are not loose. When they start to back out these motors are known to spit plugs out...
Good Luck,
Matt
You should also check the spark plugs to be sure they are not loose. When they start to back out these motors are known to spit plugs out...
Good Luck,
Matt
Use a higher octane ? I've been wondering about this. Isn't the factory engine managment calibrated to use 87 ? On a stock car wouldn't using a higher octane be a waste of cash ?
The differences between 87 and 89 is marginal at best. Octane rating is simply a measure of when the fuel detonates or "sparks up" when in the combustion chamber. If your octane is too low, yes you will get a ping because it is detonating too early. Give 89 a shot, it won't make much of a difference or a difference at all as far as the ECM is concerned.
Under most conditions, 87 octane is fine. Under adverse conditions, knock will occur. The 4.6 SOHC has no knock sensor for spark retard. Higher octane gives you more protection from knock. Given the small price difference between 87 and 91+, I'd just run a full tank of 91 or higher octane and see if the problem persists. If not, you have two choices - start running higher octane regularly, or get it checked out. I'd recommend getting it checked out by a Ford tech either way.
FWIW, I have been running either 89 or 91 in my Mustang for years. The price difference is minimal. If you buy 500 gallons a year and pay an extra $0.10 for gas, you are paying an extra $50 a year. Only an extra $100 a year for shelling out an extra $0.20 a gallon for premium. You could make that up by simply taking it easy on your tires and making them last an extra two months. I get better mileage out of premium gas (1-2 mpg) as it is, so I fail to see it as a "waste of money." I consider it cheap insurance.
Yes, although i think the GT's are technically borderline to requiring 89 octane.
Evern since new, my GT has occasionally detonated in warmer weather at upper RPM's. Doesn't do it all the time in the summer, but enough to worry me.
So i ran a tank of 89 octane through and it did not do it anymore, so i've run 89 since.
The cause? I do not know. My car has done it since practically new.
the98stang
Active Member
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