Another S52 swap... but this time with a newb!

[jahnaboi]

Anyone have a vacuum line diagram? For some reason I seem to have a vacuum leak so my car doesn't want to idle but I know I connected every line where it should be....

I currently have the vacuum lines connected as so...

Crankcase (valve cover) - 2 lines - 1 large to throttle body boot 1 small to icv nipple
FPR to intake manifold near Intake Temp sensor
ICV - 2 big : one from intake manifold to icv, and one from icv to throttle body boot

Am I missing something? My car is making a noticeable "air is leaking from somewhere" sound. None of my gaskets on my intake manifold are bad and I highly doubt its my injector o-rings as they are still pretty new.

This leak wasn't here last time... and it just popped out of no where... could it be a faulty icv that isn't opening up causing back pressure to build up hence the horrible idle that won't stay up on its own?

[e30serg]

Do have a stethoscope? A length of vacuum line will do. Maybe it's one of your gaskets, even though they are new? Did you torque everything correctly?

[jahnaboi]

Yea, that's the thing. I took my intake manifold off 3 times to double check everything... I mean everything... =/ There's no blistered/busted vacuum lines, or anything that is loose. I just don't understand. It started on Friday night. At around 2 am in 40 degree weather I decided to flush my coolant several times as there was some rust from it sitting for a while in the engine when I bought it. So after I flushed the system about 4 times, just buttoned everything up and put it back in the garage. Keep in mind, it ran / idled perfectly when I put it in the garage and turned it off.

So I wake up the next morning, start the car and it started then shortly after the idle dropped then stumbled then died. So, I was like okay... weird. So I start it back up and it doesn't even want to idle so I give it some gas to maybe warm up the car and see if it'll act any different yet nothing. When I let the gas go, the idled dropped then died... No idea how it could go from running great to dieing and sounding like it has a mean ass vacuum leak... any inputs?

[e30serg]

Is the intake the only thing you removed? It's gotta be around there. No stethoscope? Maybe re-torque and re-tighten all bolts and clamps? Maybe you knocked something loose? If you can hear it without using anything to help, it must be pretty big.

[e30this]

What about the hose on the back of the intake that goes to the ICV??
If one of the clips is broke then it will cause idle issues. I had this problem with mine.

If you cant seem to find it by looking around then grab a can of brake clean and while the car is running spray it around all of the vacume lines and the intake.
If the idle jumps then you found the area where your leak is.

[vr4boy]

i had a vacuum leak at the one of the nipples on the brake check valve that caused my idle problem.
it doesnt looked plugged basing on the pic of your booster.
check it out....
btw:
i drilled and tapped my extra temp sensor in the head-was not too hard-make sure you're perpendicular to the drilling surface and go slow....
hope this helps and very nice swap;-)

[jahnaboi]

Hey bud, thanks for the compliment. As far as that hose, it is connected to the intake manifold but I'll try putting a clamp on it to make sure. This is annoying me so much... I wanna drive this thing!

On the brighter side... The temp gauge adapter works fine! Woot. Reads accurately too as anticipated. Also, my vanos rattle isn't present anymore! 30 bucks to fix that stupid shit compared to a dr.vanos unit. Although maybe down the line I'll grab a dr.vanos unit but not at the moment.

I'll try looking over everything again...

[e30s52]

Is your IAC still hooked up?

[jahnaboi]

What do you mean is it still? At the time while the car was running it was still connected. Don't see what that has to do with anything.

By IAC I'm assuming your talking about the ICV?

[e30this]

Did you try what I said in post 262??

[e30s52]

Idle air control valve. maybe it came loose and you have air slipping past it somewhere.

[jahnaboi]

I checked the all the hoses that deal with any sort of vacuum. I removed the damn intake manifold off again...

While trying to diagnose the car while running, the noise sounded like it was coming from the rear half of the intake manifold... towards the firewall.

I'll try your method when I put it back again e30this. Even with the leaking vacuum sound, I found this much out... With the hfm plugged in... it ran like shit and would idle. When I unplugged it, the car immediately acted different and was more responsive... any ideas? Could it be a faulty hfm causing my idle problems/throttle problems? Don't see why it would work then the next morning not work....

[itsbrokeagain]

I checked the all the hoses that deal with any sort of vacuum. I removed the damn intake manifold off again...

While trying to diagnose the car while running, the noise sounded like it was coming from the rear half of the intake manifold... towards the firewall.

I'll try your method when I put it back again e30this. Even with the leaking vacuum sound, I found this much out... With the hfm plugged in... it ran like shit and would idle. When I unplugged it, the car immediately acted different and was more responsive... any ideas? Could it be a faulty hfm causing my idle problems/throttle problems? Don't see why it would work then the next morning not work....

could be..did you crack the intake manifold pulling it on and off by any chance?

[jahnaboi]

Lol... I wish I cracked the intake manifold... would be easier to deal with than putting it on and taking it off only to find out nothing ...

I triple checked the intake manifold for cracks anywhere and everywhere... even put Permatex everywhere where it didn't need any, be just to eliminate more probabilities...

[Mohammed_A]

i had the same problem once with a m50 motor, my problem was the intake was warped somehow and even the gaskets could not seal it....

does your motor have a crank case valve??? if it does then check that...