Cadillac Repair: 1994 seville sts, voltage dips, solinoids

Question
i had my exhaust pipes redone w/ 2 1/2" pipes, a hi-flow magnaflow cat, and 2 19" edelbrock rpm mufflers. this was yesterday afternoon. after about 2 hours of driving, my check engine light went on, my trannie was shifting odd, and my battery voltage dipped below 10 volts. Can this have been caused because my computer needs to be reprogrammed or is it something else?   oh and my alternator is 3mo old.

Answer
Hi Gordon, Changes in the exhaust system, specifically the back pressure, can have an affect on the egr valve operation and turn on the check engine light. The fact the battery voltage dips below 10 volts may or may not be related to the exhaust install but when that happens it confuses the computor and as a result shifting, because there are electrical shift solinoids inside the trans that control the gear changes, as well as other things will be affected and the service engine light would turn on. I would get the codes read and return to the shop that did the exhaust work and see if they disturbed anything that would cause these problems. You shouldn't have to pay for them to check to car over at the exhaust shop. As an example an oil change was done and then the engine wouldn't restart afterwards because there was a wire near the oil filter and when the tech removed the filter with a big pliers he damaged the wire insolation and blew the fuse. Start with the inspection, get the codes read and then have the battery and chargeing system tested if nothing else shows up. Happy Holidays. Bill