Blackbob

So if you've read my previous thread you know I'm working on a 87" Z31 with various mods and almost none of the stock manifold and emissions parts. VG30 turbo 5spd aftermarket fuel pump(so I've beentold,slightly bigger turbo,modified intake manifold, intercooler,almost whole nine yards. Car initially would run but have no throttle response. We then found a few vacum leaks and sealed them up. The funny thing is no she wont idle at all. We have to hard wire the fuel pump because there is a short somewhere in the system. Turned fuel pressure down to about 35psi which from what I understand is ideal for our setup on low boost. Swapped out the TPS and mass air on it with one of another Z similar setup but a year older. The older Z is mostly stock but runs fine without the mass air unhooked once the car is already running. Will start without the TPS unhooked but wont run higher than idle. Ok,fine,makes sense.....Now the 87 (the car in question) will not start unless the throttle is cranked atleast a 1/4 back and you have to play with it too. Once running it's at about 1-1500rpm but with the assistance or someone hold back the throttle. Once you let go it shuts off fatser then you can say stop.Takes a few seconds to start it up and sounds like it's running on three cylinders. I heard something about a drop resistor but didn't get to much info on it. Right now I have it narrowed down to either not enough fuel or too much fuelwith a combination of a bad MAF cannection maybe,anymore clues ?

~BB~

jfairladyz

Sounds like the idle speed is too low. Which probably means that the idle control is bad or it's circuit has a problem somewhere. The previously mentioned vacuum leaks were probably allowing enough air into the engine to allow it to idle but were becoming a hinderance once the throttle was applied. Then when you sealed up the vacuum leaks you took away the cars ability to idle. Thats all just a theory, but you may want to look into it.

Blackbob

Your theory is very much the truth,like I stated before, alot of the factory props are not equiped. The idle speed is also one of them I belive. So now it is back to square one. I thnk it's about time to consider a new engine wiring harness.