I just finished putting a fresh 305 in my RS. The mods are an LT1 cam, open element filter, hedman headers/y pipe, and lower temp fan switch (if that even counts as a mod). I have my timing set at 7* btdc. It runs strong around town...but when I'm on the highway for about 10 minutes, the service engine soon light comes on. It stays on until I park the car for a while. I don't notice any difference right away when it comes on, but when I get off the highway I have no power whatsoever. Has anyone had, or recognize, this problem? Any recommendations would be really appreciated.

 

Scan for error codes. My first guess is that you'll find at least a "32".

 

Will you please tell me what a code 32 is? Also, does OBD1 store intermittent codes? I can't remember if it's only OBD2 that does that.

 

A '32' is an EGR system fault. GM's OBD ECMs store error codes for the last 50 engine run cycles. There is no such thing as a "pending" DTC in the older ECMs - it's either a fault, or it isn't.