I have a 2006 sorento ex 3.5L. It had a blown head gasket so I took off the heads and took them to a machine shop to check heads. They shaved the heads to make sure they were flat and strait. I put everything back as it should be replaced water pump while I was there and also timing belt. I turned the crank so the timing marks were lined up, the lined up the marks on the driver side head as they are marked, then lined up the other head sprockets as the timimg marks state. Now that everything is back together I get nothing. I did check and it is getting fire at the spark plug and gas but nothing. I checked compression and it want read anything........ It did backfire one time while turning the engine over. I am lost on this stupid thing now. I would love to have some advise on what to do next. DIY Shadetree Mech.