1997 SS with the D-1 twin intercooler set up, on a stock tune they set up a fireball ignition with this set up (with boost retart box) set to retard upon boost with the replacment MAP sensor, the car runs like absolute crap (missing very badly spewing black) they also put o2 meters on to read the air/fuel ratio, only time it starts to lean out a little is when it starts makin boost and then once i does it pahtens up even more (richer), a shop did all this work all at once, Blower, FIREBALL ignition, retard box, FMU, adjustbale fuel pressure regulator. They have a fuel pressure guage hooked up to the car and when you turn the car to on it only makes it to 30 psi and once the pumps turn off (dual pumps) the pressure drops rapidly down to zero. could not enough fuel pressure cause the injectors to linger open longer (on stock tune) and run very rich? Also, they installed the D-1 with the #14 pulley, this is a stock motor/tune, could this have any effect in why the car runs like crap? vacuum/boost guage read zero vacuum/boost at idle (hooked up right at the intake elbow) and almost 10 lbs at 4000 rpms, car just spewing black smoke. Any and all help is apreciated! Thanks.

-Mark

 

You're running a 14 # D1 on a stock motor? Hope that isn't your daily driver.

Also, sounds like your vac/boost gauge isn't hooked up properly. Try splicing the connector into one of the lines on the driver side of the intake manifold. That should give you a better reading.

As for the fuel pressure, you should be seeing ~ 43 psi with the vacuum line to the regulator unplugged and around 38-40 with the line attached. I can't say how high your fuel pressure would be under boost as that is dependent upon the FMU. You may want to check your adjustable regulator as some of them have been known to blow the diaphram and begin leaking fuel directly into the manifold.

 

i'll check the regulator, could very well be a problem, i'll move that vaccuum/boost line too, cars not mine but nor am i the driver, but i gotta fix it. He took it to a shop got overcharged and still not runnin good, if that FPR is leaking that would make ab it of sence but i was wondering were it can dump into the intake? Only through injectors right? thanks its a good start for tomorrow morning.

-Mark

 

There's a vacuum line that runs from the passenger side rear of the intake manifold to the top of the fuel pressure regulator. If the diaphram starts leaking, then the motor will suck fuel through that hose directly into the manifold. I speak from experience there.

Ps. Don't beat on the car till you have it all figured out.

 

definetly wont be beating on it, yeah my stock fpr went out on my z, replaced it with another stocker, got a much better idle but that was about it, i do remember checking that vacuum line on top before and it was dry so i'm sure its not goin through there, but i will definatly check that again. I'll keep updated.