I have a 90 5.0 gt vert that I bought from a second owner last summer. When I bought it I was told that he had just put a new magnaflow offroad x-pipe on it. (please forgive me if I don't sound knowledgable about these thigns...truth is I'm not, but I have enough friends who are to get through The biggest problem I noticed was that it got terrible gas mileage. The power was fine, compression was sitting at 150 on all cylinders, etc but I was getting 15 mpg on the highway, as opposed to my friend w/ an 89 5.0 lx getting 25'ish. My guess was that this was the cats, and the engine was not really being efficient at burning gas.
Now on to recently. This past summer it was leaking oil a little bit so I took off the intake manifold (all with the help of friends) and the covers and put all new gaskets on for everyhting (i painted them all while they were off too). Tihs solved the oil leak, but when everything was put back together I got a check engine light . I took it to autozone and they said it was a vacume leak dealing w/ the EGR valve. He said it probably had more to do w/ the cats and o2 sensors than anything I had touched. I also noted immediately after this that when i start it from cold, it stalls out as soon as i put it into drive if i dont' rev it a bit. Once it's goign or i've reved it just like 2 seconds it's fine. Also power has been down a little bit.
Now I'm trying to sovle both that whole situation and the gas mileage. Do I need cats? Do i need to mess w/ O2 sensors? Did I break something? lol
any help would be greatly appreciated. I have plenty of people who know what they're doing helping me w/ actually doign stuff, so if you have any suggestions that would be fabulous.
Now on to recently. This past summer it was leaking oil a little bit so I took off the intake manifold (all with the help of friends) and the covers and put all new gaskets on for everyhting (i painted them all while they were off too). Tihs solved the oil leak, but when everything was put back together I got a check engine light . I took it to autozone and they said it was a vacume leak dealing w/ the EGR valve. He said it probably had more to do w/ the cats and o2 sensors than anything I had touched. I also noted immediately after this that when i start it from cold, it stalls out as soon as i put it into drive if i dont' rev it a bit. Once it's goign or i've reved it just like 2 seconds it's fine. Also power has been down a little bit.
Now I'm trying to sovle both that whole situation and the gas mileage. Do I need cats? Do i need to mess w/ O2 sensors? Did I break something? lol
any help would be greatly appreciated. I have plenty of people who know what they're doing helping me w/ actually doign stuff, so if you have any suggestions that would be fabulous.
3.73 is a great gear for street and track. Go with a off-road x-pipe. It won't only solve your o2 problem but your exhaust will sound alot better (louder). Good Luck!
