Most main relay issues are black and white. The car either runs or it doesn't. However, I noticed something over the past 24 hours that has me wondering about some performance issues. This may be the key to undiagnosed problems. Believe it or not, I've never had a main relay issue with any Honda I've ever owned. My first trial by fire with the infamous Immobilizer Unit was over the past couple days. My first 6th Gen Accord as well. During the process of figuring out what was up, I swapped the main relay to no avail. After figuring out that the immobilizer unit was the culprit and getting the car started, I decided to leave the new main relay connected even though it was unnecessary. During the test drive, I noticed that the car seemed to be running smoother. I have noticed a very slight hesitation or misfire during the month that I've owned it..especially in gears 1, 2, 3. The idle was perfect and there were really no other symptoms. Just the slight hesitation when under load. With the new relay, the car seemed to be running noticeably smoother. For experiment's sake, I came home from the drive and put the old relay back in. The hesitation seemed to return when I took it back out for a ride. I'm thinking that since the main relay controls both the fuel pump, ECU, and other key parts, a relay that is failing / fluctuating in voltage, etc. could totally cause some of these phantom hesitation and other performance issues. Issues that could be blamed on distributor / inner distributor parts / plugs / wires / etc. I've swapped back and forth twice and am going to swap a third time to be absolutely sure. But it seems that an even slightly failing main relay can cause these issues. Has anyone else dealt with this issue? Or come to the same conclusion? It really seems to be the case.