few mysteries i need help with solving

Hey all...
Well, I bought my fiero, and Im loving it...however, Im having a few minor problems. Ive spoken to a few other fiero owners and they have heard of similiar issues. If anyone knows whats going on here, please let me know!

1) Check engine light comes on. It only does this at about 220 degrees or so, and I always notice it when I take my foot off of the exhelerator. Ive heard that it could be an 02 sensor, so nothing absolutley serious that needs to be fixed right away? My fiance thinks it might have to do with the exhaust...or be incorporated with the next issue
2) Loud rattling noise coming from the exhaust when car is first started. When in neutral, the noise goes away, and once its driven for 5 minutes or so, totally gone. We installed new exhaust hangers, assuming that that was the problem, because they seemed a tad loose. It didn't help at all, and heard from others it might be cat converter. Any ideas?

Thanks!

The rattle could also be the exhaust pipes behind the engine near the firewall. Pop the deck lid and then start the engine. If it starts rattling take a long wooden stick and poke it down on things in the area of the rattle until you place it on something that you will really feel the vibration on the stick. There will be your source of the rattle.

Steve

I'd be happy to help you solve the check-engine light mystery. While I don't have any experience with Fieros, diagnosing engine problems is similar to any other older fuel injected GM car or truck. First, locate the ALDL connector (it SHOULD be mounted under the dash, some have a protective cover that pops off) It looks something like this :

|O|O|O|O|O|O|
|O|O|O|O|O|O|

Take a paper clip and bend it in a u shape, then insert each end into the 2 right-most top holes. (I've marked them red for you) Then turn the key to the run position but DO NOT START THE ENGINE.:nono:
After a few seconds, the check engine light will start to flash codes. Codes are displayed with each digit about 1 second apart and each seperate code 3 seconds apart. The first code should always be 12. ( one flash followed by 2 flashes after a 1 second pause) When all codes have been displayed it will repete them again starting with 12. Once you have recorded all stored codes, turn off the key and remove the paper clip.

Let me know what codes, if any, display, and also the year and engine type (2.5L L4 or 2.8L V6)

PS - the worst a bad oxygen sensor will do is decrease performance and fuel economy, it's safe to drive a car with a bad oxygen sensor. However, if you live in an area with emmisions testing your car may fail the test. :uhoh:

Many time when the check engine light comes on it will spit out error code 32 EGR problem, which can be caused by a vacuum leak in the EGR system, somewhere. A real PITA to locate, however some leaks are in the small vacuum lines that run under the intake manifold. They tend to crack with age. Find what the error code comes out for more information. Old car with many miles many sensors could be going bad.

Hey, Your Check Engine Light Is Coming On Because Your Catalytic Convertor Is Shot. It's Rattling Because It's Worn Out, Clogged, And Broken Up.when You Let Off The Gas The Engine Can't Get The Air And Fuel Out At The Rate It Needs To Because The Back Pressure Is Too High. It's Running Rich At That Point And Causing The Check Engine Light To Come On. If You Let It Go It Will Eventually Start Dying On You Because It Can't Breathe.