between shifts there is a loud rattle sound in front end almost sounds like something is loose?

1999 SATURN SL1
140,000 MILES • 4 CYL • FWD • MANUAL
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DOMINIC28AB
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I have a 1999 saturn sl1 5-speed the car runs great except for when rpm's get up to about 3000 between shifts there is a loud rattle sound in front end almost sounds like something is loose.If I stay under 2500 rpm's there is no noise at all. My check engin light comes on abut every 3 days for about 4 or 5 hours and then goes off for a few days. Before light comes on it seems to idle a little rough on start up then is ok again. Thank you in advance for your help.
Jun 2, 2010 at 6:37 PM
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JACOBANDNICKOLAS
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Hi,

The first things I recommend checking are the heat shields on the exhaust system as well as the catalytic converter.

Often times the heat shields will come loose or break and rattle at a specific RPM. However, that wouldn't set the check engine light. What I suspect is that the internal components in the catalytic converter are loose. If that is the case, you can hear a rattle and if they partially block the exhaust airflow, it can have a rough idle and set the check engine light.

Do this. Take a rubber mallet and tap on the exhaust to see if you can reproduce the sounds. Have a helper locate the source of the sound.

If you look below, I attached a pic of the exhaust system. I highlighted the catalytic converter and circled all the heat shields.

I hope this helps. Let me know if you have other questions.

Take care,

Joe

See pic below.
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Jan 17, 2022 at 7:12 PM