daves280z Posted April 10, 2015 Share Posted April 10, 2015 Hi, I've had my Z for about 6 months now and just started to do some updating and now I'm looking for help. My 78 280 was running fine except for an exhaust leak so I replaced the intake manifold gasket thinking that was the problem While removing the intake and header I found the leak was actually coming from the EGR tube broken at the header. I went ahead and replaced the intake gasket and deciced to just get rid of the EGR as many others have done. I blocked off all the EGR holes to delete it. While everything was apart I decided to replace all vac lines and fuel hoses. Then I decided to clean the throttle body while it was all apart. Got all that done and put back together and went to crank. It cranks but races to 3000 RPM's for 2-3 seconds and then idles down and cuts off if you don't give it any gas. If you give it gas it races back to 3000 RPM's and keeps doing the same routine. Ive checked back over all the plugs and vac lines, the only problem I see is the wire that goes into the bottom of the throttle body where the BCDD is, broke off at the connection where it screws into the BCDD. I'm not sure what you call that sensor and I'm not sure if that would be causing the idle issues or not. Any help would be appreciated. Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 10, 2015 Share Posted April 10, 2015 That wire actually powers the solenoid in the BCDD. There's no sensor in there. Did you take the BCDD off or apart while you were cleaning the throttle body? Sounds like a vacuum leak of some kind. A leaky BCDD might be the problem. Crank means engine turning over, or crankshaft spinning. Crank is what the starter does, it used to be done by a human with a crank handle, that's why people still say crank. After cranking comes ignition, then starting, then running. Quote Link to comment Share on other sites More sharing options...
daves280z Posted April 10, 2015 Author Share Posted April 10, 2015 Nope didn't take it apart. I've been going thru the fsm and noticed my air regulator was on backwards and it could cause high idle, turned it around and still same problem. I did check to see if the flap in it would still move and it did. Cleaned the connector to it was corroded, didn't help. I will get my circuit tester from work tomorrow and check the wiring harness. Quote Link to comment Share on other sites More sharing options...
NewZed Posted April 10, 2015 Share Posted April 10, 2015 You could also turn up the idle speed, using the idle adjustment screw. That lets in metered air so the engine will stay running. Then spray carb cleaner at various potential leak spots. Your EGR work is a prime suspect also. Quote Link to comment Share on other sites More sharing options...
Redwine automotive Posted April 11, 2015 Share Posted April 11, 2015 Hi,NewZed is on target sounds like a big vacuum leak, check your work at the manifold gasket. Quote Link to comment Share on other sites More sharing options...
daves280z Posted April 12, 2015 Author Share Posted April 12, 2015 Yep you were right, like a idiot(slaps forehead) I for got to plug the hole on the bottom of the intake where the EGR tube was. Plugged it and back to normal. Thanks for the help. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.