high speed rattling

[bunyun76]

i have a 91 X 4.0, 2wd and it has about 200k worth of mileage on it maybe more but i guess i will never know for sure. Anyway, my question is i noticed that at high speeds around 70 and above if i continue to have the throttle set to try to accelerate i get this ratttling noise coming from the engine. But if i eaz off enough to maintain my speed the rattling goes away. THis is very annoying especially in highway areas going uphill since the car is constantly in acceleration mode. What could it be other than that she runs fine.

 

[Howard]

The rattling you are referring too sounds like pre-detonation or pinging. This can be caused by a number of things. Excessive carbon build up inside the combustion chamber. An air leak in the inlet manifold area leading to a weak mixture. Bad spark plugs or leads. Dirty IAT and MAF sensors.