I'm doing a compression check on my 92gt, i did one side and was going to let the car get warm again b4 i did the other. When i start the car up i get lots of backfiring in the headers. Is this from the unburned fuel? I didn't disconnect the fuel, just the ignition when i was doing it. Just want to make sure it's ok to run it like that. Do i have my wires crossed or something?