RB20 Trouble shooting, could use help!

[Cleveland180]

Hey guys,PROBLEM 1: My Rb is really hard to start, sometimes you can crank it for 5 seconds with no start, and then eventually it will sputter to life. PROBLEM 2: My Rb will not rev, it decides what speed it wants to run at, and after that if you add gas it will pretty much just stop, by stop i mean the engine will shudder and it will jump back down to where it likes to rev...I think the two problems are related and here is the trouble shooting I have done so far maybe someone can make sense of it.

When the vacuum line to the IAC is plugged with a hand it changes the idle to something more smooth, but still wont let me rev.When the O2 sensor is unplugged there is no change in behaviorWhen the MAF is unplugged there is no change in behaviorThe Gasoline is Fresh Sunoco 93 octaneThen intercooler piping is hooked upBrake booster line is not hooked up.

any ideas?

Thanks,Dave

[mott6904]

check for boost leaks and make sure your maf wiring is correct.

[RustspecS13]

zerothread/328569

Try that for your starting problem. But it does sound like you have a leak some where. Spray everything down with carb cleaner to check all your connections, or make a boost leak tester.

Maybe you could try cleaning out your iacv with some brake cleaner too, and make sure its wiring is ok.

~Alex

[240daveTX]

hook up the brake booster line. car wont run right without that

[Cleveland180]

I hook up the brake booster line by tieing into the same line that runs the IACV correct?

Thanks, I also think I made the mistake of doing the orange to orange wire inside the car, sadly i don't get to work on it for another two weeks, but I will hopefully be able to go to it and just fix the problems quickly rather than stand around and make wild a** guesses.

[RustspecS13]

No the brake booster has its own line....its has to be connected to the plenum so it gets as much vacuum as possible.

And the IACV gets its own line to that T's into the AAV thats down by the throttle body.

~Alex

[Yellow4g63]

Someone post up the stock vacuum diagram because I forget how s*** goes to the IAC and AIAC ect ect.

[Cleveland180]

ok, I Think I can Manage that, The IACV and AAV Both share the line that connects to the elbow pre-TB and is there a nipple on the manifold that works best for the brake line?

[mott6904]

I believe the brake booster line connects to a nipple above the iac. There should also be a check valve in that line so the booster holds vac and doesnt allowand doesnt allow boost.

[Yellow4g63]

I think I got mine figured out, going back tomorrow to work on the car some more. Fukin Forward facing intake manifold, Had to pull it to change my Thermostat lol what a pain in the azz.