[jims87iroc]

i recently installed a 5.7tpi in my 87 iroc. it had the 5.0tpi from the factory i swaped all existing components. i now have a lean idle condition and repeated stall in closed loop operation. my qwestion is. does anyone know if the components are compateable (injectors etc,) please respond or direct me to someone who can. all my thanks JIM

[Dave Birdwell]

How do you know the idle is lean? did you have it on a scanner? Did you use the TPI and fuel rails from the 305? Did you use a 350 chip? Does it idle fast or slow? Does the IAC motor try to control the idle?
In closed loop the mixture is computed from the input of the sensors. In open loop it's ran by a set paramiter of info.
Give me some more info and I'll try to help you out!
Dave

[68SS396]

If you used the original 305 injectors then there's your answer. The TPI's are the same but the injectors are different between the 305 and 350.

[jims87iroc]

this reply is for dave birdwell. i used the 305 fuel rail and injectors. i checked block learn at idle with a scan tool it read consitantly high about 140. i also set tps and min idle to spec. it has a new o2 senser and no vac leaks,timing is right. i also checked part #s for injectors that year 305 & 350 injectors are not the same, could this be the cause. thanks for your help. JIM

[tom3]

You can sometimes help this with an adjustable fuel pressure regulator. Increase the pressure some and see what happens. When idling roughly, might just try unhooking the vacuum line to the present regulator which will give some increase. Also, does this 350 have a computer compatible camshaft. Excess duration and overlap may cause problems. tom