Just got a 87 Iroc z. I have a rattle noise up front during acceleration under load. However, when I accelerate over 80mph hard the check engine light will come on and no more rattle even at low speeds. When I turn the car off and back on, no more check engine light but the rattle is back. Thoughts?

 

Is the rattle spake knock? this would sound like marbles under the valve cover. If so, It sounds like you have a sensor reading bad causing the engine to run lean, When the check engine light comes on the ECM goes into LHM and runs on a pre- defined fuel mapping which is rich. I assume this is a 305 TPI set up?

You will need to know what that code is being left by the check engine light. It should store the code even when the light is out.

 

Yup sounds like marbles. It’s a 5.7l 350 fuel injected. I’ll read the codes. Thanks for the help.