Unknown Vacuum Line

[rquaale]

I redid my head gaskets a couple of months ago and ever since I put it back together it ran super rough and kept throwing a misfire in cylinder 6 I traced it down to dead injector and it runs better most of the time. There is a vacuum line connection (I think) under the intake plenum that does not connect to anything its not pvc valve and when its covered the truck runs perfectly fine but if I remove the rubber cap i have over it the engine almost stalls and dies and runs real rough but smooths out when it gets covered again. Any idea where it is supposed to go. Its on the underside on the back and it also points towards the firewall.

 

[PlumCrazy]

Is it the line that is supposed to go to the fuel pressure reg? or the line that feeds
HVAC panel for the recirc door actuator?
Sent from my DROID RAZR using Tapatalk 2

 

[stmitch]

Does the truck have EGR? There is an EGR controller that mounts to the back of the coil pack that is vacuum operated, and ties into the fuel pressure regulator, and HVAC bulb like PlumCrazy mentioned.

 

[rquaale]

I think it has an EGR valve but there is nothing by the coilpack but there is something that looks like it should be the EGR valve that bolts directly to the front of the intake plenum and I have absolutely no idea where it goes because I cant see any hoses that dont connect to anything and there is no hose on it. But i can hear a hissing where i think the EGR valve is and now everything is blowing through my defroster. And after looking around online I think that the line that goes under the plenum must connect somewhere and im just not seeing it.

 

[Lil-Pony]

What year is your truck

 

[rquaale]

What year is your truck

98 ranger xlt, king cab with the hidden doors, 3.0L V6, rwd
I have to work until straight until fri so i wont be able to try anything complex until then but will keep checking back here daily and trying simple stuff

 

[rquaale]

ok i went out today and turned on my a/c and it blows through my defroster so i replaced the egr valve gasket and nothing. I also uncapped the what im guessing is the vacuum line and my engine almost stalled out and then it picked back up but had a very rough idle and my check engine light came on dont know why and the closest parts store that can read it is an hour away, but as soon as i put the cap back on the engine picked back up and smoothed out. any help would be greatly appreciated.

 

[stmitch]

Disconnecting the vacuum line allows unmetered air into your engine. That causes the computer to over compensate which causes a rough idle. Disconnecting the line is basically causing a vacuum leak, and doesn't really mean anything as far as diagnosing your issue.
If your truck has egr, and is a 99, there should be a small black canister bolted to the rear of your coil pack. That's the egr controller I mentioned. There will be small diameter plastic lines that run from that cylinder to the fuel rail, driver fender well, and the back of the upper intake manifold. Double check to make sure those lines are connected properly, and not damaged.

 

[adsm08]

Pics. Need pics.

 

[rquaale]

Pics. Need pics.

cant get pics of where it is because it is underneath the intake plenum so there is no way to get a pic of it
also it throws a code for the egr pressure feedback sensor cant remember which but had it cleared and let
it warm up idleing and then drove it for over an hour and the check engine light did not come back on. so i
dont know if that helps or not

 

[Rearanger]

I think it has an EGR valve but there is nothing by the coilpack but there is something that looks like it should be the EGR valve

An EGR will have a connection to the exhaust system, either a metal tube or a flange mount.

everything is blowing through my defroster.

You have not hooked up the blend door actuator system (HVAC). Does your truck have a vacuum reservoir - a large plastic canister maybe somewhere near the firewall which that missing vac line may go to?

 

[rquaale]

Ok i went out there this morning with my gf (tool gopher) and took off the intake plenum and she noticed a wire similar to the one that goes on top of the egr valve and it fit over the port so i hooked up bolted the plenum back on and after taking it down the road everything started to work the same as before. the wire comes from a very large bundle of wires and most of them run to a black box on top of the plenum so I dont know what that wire was but it seems to have fixed my issue. Im taking my truck on a road trip this sat and going through some mountains so I'll know if it works under load or not.