I recently installed a new upper and lower edelbrock performer intake and i also installed bbk 70mm throttle body and spacer my 5.0 is a 1987 no masss air sensor. My car ran fine before i installed the peroformance parts but after i put it all back together the car idles at approx 3 thousand rpm. I can adjust the timing so that it is at about a thousand rpm but the car will not move it back fires horribly when it does backfire is when its set at 3 thousand rpm if i wanna drop the idle about a thousand without changing the timing i can disconnect the map sensor but all that does is make nothing but black smoke (unburnt fuel) i need help i dont know what i can buy or change or what i should have installed when i put on all the performance parts and i was wondering if anyone had any ideas?

 

Sorry i cant help you

 

Sounds like a vacum leak...maybe the lower intake has a leak.

 

use a vacum gauge and check it for leaks...mine did that at idle and my carb was leakin a vac

 

you're problem is that you cant do performance mods to a speed density 5.0 without gettting the a/f ratio retuned therefore your car is running like sh*t. soo convert it to mass air

 

You can do those performance upgrades, even though it's speed density.....disconnect the IAC and adjust the throttle blade stop screw all the way back.....if the idle speed is still too high, you have a vacuum leak that needs to traced and corrected, or a faulty IAC. If the cam is still the stock one....it's a matter of identifying what's causing the problem. My 2¢.

 

well its been a long time since this post and i sold the car and got a new mustang lol......that car was a vacume leave...the uppper intake was cracked in 3 places.....guy who bought it put the stock intake and throttle body all back on it and it was faster...realll fast