Blackbob Posted April 29, 2006 Share Posted April 29, 2006 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~ Quote Link to comment Share on other sites More sharing options...
bjhines Posted April 30, 2006 Share Posted April 30, 2006 I gotta say it... TPS???? Quote Link to comment Share on other sites More sharing options...
Blackbob Posted April 30, 2006 Author Share Posted April 30, 2006 nope...everything checks out ok. The Idle air valve was assumed to be the culpret. But I haven't been able to do more test since a few days ago. I'll keep you posted. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted May 4, 2006 Share Posted May 4, 2006 I had all kinds of problems with setting up my idle with my vg30et. i found that with my mods (sound similar to yours) my idle air control (valve on drivers side of engine) the hose that goes from the intake piping side of the turbo to this valve would not let me adjust the idle, and by the time I got it to idle, but adjusting fuel pressure, timing, throttle plate position etc, the car ran like crap. In a quick summary, we tested this theory by using a visegrip to pinch off that rubber hose (approx 3/4 dia). The car suddenly ran smooth. To this day, i still have a welded up nut with a tiny hole jambed inside the pipe to restrict the air flow. Its been that way for years now. On another side note, i thought that I didn't need that valve, so I removed it.. wrong.. car idle just surged back and forth from normal idle, to 2000rpm back and forth. BTW how did you test/setup your fp? at idle with the vacuum hose removed and plugged? I'm running about 25psi using the above measurement method. Scott Quote Link to comment Share on other sites More sharing options...
Blackbob Posted May 4, 2006 Author Share Posted May 4, 2006 I had all kinds of problems with setting up my idle with my vg30et. i found that with my mods (sound similar to yours) my idle air control (valve on drivers side of engine) the hose that goes from the intake piping side of the turbo to this valve would not let me adjust the idle' date=' and by the time I got it to idle, but adjusting fuel pressure, timing, throttle plate position etc, the car ran like crap. In a quick summary, we tested this theory by using a visegrip to pinch off that rubber hose (approx 3/4 dia). The car suddenly ran smooth. To this day, i still have a welded up nut with a tiny hole jambed inside the pipe to restrict the air flow. Its been that way for years now. On another side note, i thought that I didn't need that valve, so I removed it.. wrong.. car idle just surged back and forth from normal idle, to 2000rpm back and forth. BTW how did you test/setup your fp? at idle with the vacuum hose removed and plugged? I'm running about 25psi using the above measurement method. Scott[/quote'] First off scott let me say you have answered one question that no one seemed to be able to answer. Secondly, to answer your question I never removed the vacum for the fp(assuming you're refering to the fuel pressure regulator) because this one was aftermarket. With the regulator unplugged it didn't respond much different.....then again to be honest I don't really remember. See the car would't and still will not idle at all. It wont even surge unless you hold the throttle 1/4 back while you try to start it. To get an idea of what I'm talking about if you unplug the TPS and MASS air on your Z. What it's doing is that. But both the mass and TPS are good. Just the idle air is missing becuase the builder removed it. Yesterday I removed the plugs and it was as follows. #1 was righ,#3 was too lean, # 5 was rich, # 2 was hit with what looked like either a valve or a piston, # 4 was soaked in oil,# 6 was rich. After seeing that I realized that the guy who cought himself builder it did a shitty *** job. So now I'm back at square one...again..... Quote Link to comment Share on other sites More sharing options...
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