I changed out the intake manifold (chasing an oil leak) in my sisters 93 1/2 ton truck. I have it all back together but when I tryy to start it the trouble begins. I turn the key and the truck will crank then back fire through the throttlebody and start up. I set the initial base timing to TDC as indicated and have checked and re-checked the firing order. When the back fire occures it blows the vacuum lne apart that serves the pcv valve. When I attach the hose while it is running it idles fine but when I give it throttle it will blow the hose off again and run. Any suggestions. I am leaning towards a stuck egr valve or that I have a vacuum leak under the throttle body?
Monday, July 31st, 2006 AT 11:13 AM