Not sure whats up now, but I think I may know. Before I go through the trouble of taking the upper plenum off again I want to know what you all think it could be.

I had some broken pieces from the vacuum lines under the plenum. They are all patched together basically and it works fine. I decided to make my own vacuum lines using brake lines, and a tube bender. Over all it was pretty simple to do, but now the engine starts, but ran like crap. Before it would fire up just fine and run around 1200RPMs. Now it sits around 900RPMs and sounds like its going to die on me, and is really rough. I do not believe I have any of the new hoses crossed and connected wrong.

Now I think that one of the hoses I made is to small and hoping that is causing the issue. There are three line sizes. I kept the original big line that connects directly under the plenum and is a pain to get at The second largest line runs from where the dogbone is all the way under the throttle body and connects there. I think I need to replace this line either back to the original, or make it out of something larger. The rest of the lines are the same size. All of my vacuum lines are the same size as the small original lines.

So before I swap out that throttle body vacuum line, do you think that could be it? If not what else could it be?

I am half tempted to just switch it all back to the original vacuum lines and see if that corrects the issue.

My engine is a built V6 from whitehorse. Since I just put it in last week it has been ran about 30 minutes and just driven around the block. The whole time it ran smooth as butter, and now its rough Here I thought I was doing something good and now it turning bad

Any help would be great.

Thanks,

Ken~

900+/- 50 is the normal idle for a 2.8. But since you said yours is built it's hard to say what it should be. Have you let it run long enough for the IAC to readjust to no vacuum leaks? Does it smooth out when you advance the throttle?
Check all the wiring connectors in the area that you have been working in. Something may have gotten bumped or unseated

Well just to rule everything out I just finished putting it back the way it was and now it won't stay running I just looked in the Haynes manual and I can't find which way the lines go. Maybe I am loosing my mind here, but I swear I did 1 vacuum line at a time. Now when I start the car it will try to start, and if I give it gas will start, but then pop and turn die. Try again and same thing happens. I then thought maybe I switched the two vacuum lines that connect the EGR vacuum solenoid. So I switched those and tried and same thing.

I have gone over and over again on every connection and they are all connected, everything is plugged in. I even thought maybe I ran out of gas so I put in 2 gallons and still nothing.

Why o why did I have to mess with it

I know last weekend after I put it in and started it, it fired right up and pretty much stayed at 1200 - 1400 RPM's the whole time I had it running. I let it run a good 30 minutes or so just to check for leaks.

So what did I fubar??

Ken~

On the first pic i notice that the hose , not the intake side , but the other end is supposed to connect on the firewall , that's the way it is on mine . 88 Gt 2.8L



i took your pic as an example

[This message has been edited by Robert 2 (edited 03-28-2009).]

Correct it does connect to the firewall and run to the front of the car. It also then connects to the medal line that runs under the plenum and connects to the side of the plenum next to the thermostat housing. Mine is too big for the hose that is attached to the firewall. In order for me to make this work I went and bought a bigger hose to connect to the medal plenum tube, and then used a coupler to attach it to the smaller hose that is attached to the firewall. This works, but does leak a little bit.

I have a forum member sending me the correct part now

Thanks,

Ken~

II it's leaking that is a vacuum lost and also, that is the vacuum for the brake booster

getting a vacuum line crossed shouldn't stop your motor from running unless you messed up the line that connect to the MAP sensor. You said that you have a built motor, does it have an aftermarket camshaft? An aggressive cam will make your motor idle more roughly than a stock cam. if you dont have a cam, then it's something else. if you have the haynes manual, check the troubleshooting part because i know it has a section for rough idle.