car wont run in lower rpms at all
 

Im working on this guys 86 NA rx7. I stuck a new motor in it then sold the car to him. when i sold the car it was in perfect running order. It had a great sounding idle because of the street port.

Now he gives me a call telling me that it wont idle at all. the damn thing wont run below like 1550 at all it just dies right away. i tore the entire UIM off and checked everything out. all of it is fine. but when i start the car up i hear a whooshing noise. when that noise stops its runs fine. But it wont run below 1550rpm. i cant find any airleaks. and this noise still wont go away. Checked all vacum hoses.
the engine has only 322 total miles on it. new everything not even broken in yet.

you sure the primary injectors are good (assuming you've ruled out vac leaks)? Do you have to keep your foot on the gas to keep it alive? Take a little while to rev up?

the injectors are fine it doesn take a little while to rev up its starts right up goes up to 2k asap

you said the noise stops & then it runs fine, that kinda rules out a massive vac leak...but you haven't figured out where the noise is coming from? Is it engine noise (i.e. varies with RPM)?

it comes and goes but it never stops. its not the normal engine noise. i tore the UIM off trying to find any leak. i cant seem to put a finger on where the nosie is coming from.

maybe the whooshing noise on the startup is the airpump?

there is no airpump because of the full exhaust

Bump

Man... Vac leak.