Timmie

Ok, I got a weird vacuum leak.


but first the setup.
a in a 91 camaro Rs.
a 3.4 base block dressed up as a 3.1.
pacesetter headers
milled heads
comp cam 260H cam ( complete kit )
airpump delete pulley. ( removed vacuumline completely, it goes now from the intake straight to the fuel lines. no T splitting here.
no vacuum orbb. again, no T splitting, it goes straight to the cruise control.
we also changed the heater control valve ( the thing that diverts water to the heater core )

now the second I move the slider from off to vents-heater-defrost. the car WILL stall, ( sometimes with an exhaustbackfire )even when I would rev it, the second I touch the panel, it will die.

anyone here got an idea ?
also tried to deattach line that goes in into the T fitting with check valve.

I attached it so that I had ( on the back of the manifold )
1)map sensor
2) brake assist
4)cruise control
the otther line on T-fitting I plugged off.
yet aagin, the second I touch the controls the car dies....

Edwardgp

Have you looked up under dash I think there is some vacuum controls up in there that go bad. These control the heater vent door I believe.

Project 3.4 Camaro

I hate to say it, but you really do have to start at the source on something like that...you will have to locate the solenoid to the door directing air flow, and go from there, which probably means pulling the dash out, and possibly pulling the wiring harness apart as I seem to remember some of the vac lines going through the wire harness conduit.

Edwardgp

I was trying to be gentle but Timmie you might have a project ahead of you.

Project 3.4 Camaro

And unfortunately since it immediately stalls, he can't just go around spraying a flammable substance around vacuum line till the engine speed changes, and I am reasonably certain he doesn't own a smoke machine for finding vac leaks, lol.

Edwardgp

Well Timmie keep us informed and since summer is coming up you will have time to get a manual to help along with asking questions here on this forum.

Maverick H1L

iTrader: (8)

Heater controls use a completely separate harness, coming out of the passenger's compartment to the lower right of the heater box (engine side of the box if you're right-hand drive). ALL wiring and vacuum stuff is in this harness.

Does anything happen when you move the temp control slider from cold to hot (the temp control slider controls flow of heat in and out of the core via the control valve via a secondary vacuum director)?

Disconnect the vacuum lines for the HVAC controls and switch them. May be backwards.

Timmie

I think i'm gonna start with something basic and install an orbb of power
then I check what its gonna do with it attached.

starting to think its gonna be somekind of combination of.
no orbb ( less vacuum reservoir ) + less vacuum total due to camshaft = almost no vacuum to keep engine happy..

Timmie

installed the reservoir, and the engine doesn't stall right away anymore. ( also put the timing right )
but yet still when I move the heater control switch to a position that isn't airco or OFF, ( Vent -heater-defrost ).
it sometimes starts surging.

so I think I have vacuum problem behind the HVAC.

btw, how do you know when the hvac is bad.
I mean, I hear hissing when I move the switch to different positions, ( specially if you put it into defrost. you could really hear het gow phhheww. ( always had that )
even if you set the contact off, and you moved the switch, you could hear it. when you moved the slider from off or vents, or heater to defrost.



I never heard it when it was 1 position for a while

Timmie

what do you mean with that ?

Timmie

looks like it has nothing to do with vacuum.
since the engine also stalls when the fan comes up.

so I checked something else, and I checked I could change the heater controls when I disconnected the blower fan.
and yes, it works.
so actualy my engine starts doing freaky stuff when something big uses power. I think its probably because I installed the new heads ( painted )
and that now all the electrical **** connected to the heads don't get enough ground.
So I'm probably gonna put in some more ground from the back of the block to the chassis. that will do the trick I guess.

Edwardgp

Yes sir I made my own grounding straps.

Timmie

edwardgp ?

you keep saying strange things....

Maverick H1L

iTrader: (8)

The HVAC vacuum control switch is on the back of the control head and is held in by 2 screws. From the sounds of it, it's either a vacuum motor line gone bad or the control switch. Go to a junkyard and grab one. Be warned... You need to take yours with you and make sure it will bolt up right. I know from experience that one from a Blazer (or was it a Caddy? IDR) won't fit our control head.

:edit: And what edward is referring to is the fact that it seems you need some new grounds to your engine. Start with the braided strap at the back of the passenger's side. I put an 8 gauge wire on there to make sure. Then, disconnect the battery and clean the crap out of the block and terminal where the negative batt terminal bolts to the engine. Do the same for the little ground next to the battery as well. Better yet, do the same for EVERY ground you see.

Timmie

look where I'm located, I only know 3 USA junkyards, 1 in belgium 2 in holland, and both ask ridiculus prices.
think about 3 dollars less then what you pay for a new part at the dealer....
I know 1 guy that asked 128 for a dodge taillight that costed 140 at the dealer NEW.

I already thought about that grounding.
gonna do that tomorrow.

Edwardgp

Maverick You said it much better than I could have. Yes made my own grounding straps soldered ends on the wires and I was good to go.

Maverick H1L

iTrader: (8)

Well, there's always eBay. Sorry I can't help more with that as I need to keep mine...