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Remove all the vacuum lines from the intake, label them. Connect the MAP & FPR to 2 of the empty ports using 2 new pieces of hose. Cap all the rest.
I did that but did not disconnect the brake booster at the tree. Should I have? Also when you say all the lines from the intake are you referring to the tree only or is there more I should have capped? I used a lot of propane today and checked everything I could. I went over the engine compartment twice with it. Thank you Sandy
I have never done a compression test. Will that indicate a possible engine leak as RLA said I could have one?
At this point is the EGR block that was suggested worthwhile?
These pictures are of the JY TB. I adjusted the stop screw so they just free up. This is not the TB that has been on the truck since I started this thread. Are these gaps acceptable? The two best fitting valves are on the original TB which is on the truck now. Also the hole in the valve is on the top of the TB, is this correct?
The point of removing all the vacuum lines is to systematically eliminate each and every accessory vacuum system as the source of the vacuum leak. You only need to pull the line off the manifold or throttle body and cap the vacuum source, you do not need to cap the line. The engine will or rather should run even if the vacuum feeds to the MAP and FPR are removed and capped. (pulling the MAP line will set a code but the computer will substitute a fixed MAP value and continue on its merry way and the FPR will simply supply max fuel pressure to the rail). All you are doing is eliminating those systems as the source of the leak. Remove everything and see if it makes any difference in the high idle. If the idle does come down, put each line back one at a time to see which one is the culprit. Make sense?
Yes it does. Thank you. Where I can, can I use my finger to cap it? You also say systematically so I assume you mean one at a time correct? When I previously removed the MAP it threw a CEL but went away when reconnected.
Can't say one way or the other with the gaps... you would have to install the TB and then follow the adjustment procedure. I would set the stop screw somewhere in the middle, install, and then go through the procedure.
Can't say one way or the other with the gaps... you would have to install the TB and then follow the adjustment procedure. I would set the stop screw somewhere in the middle, install, and then go through the procedure.
Before I do that I want to complete the vac leak testing. Pls see my last post that I replied to you about the sequence.
I would take them all off at once and cap each source point with the engine off and then start the truck and see if there is any idle change. If there is no change then the problem is elsewhere. If there was a change then put each line back one at at time to find the culprit. But the reverse would work, doesn't really matter. I would cap each port with a rubber vacuum cap, but the finger approach will work for the smaller ports I think.
I would take them all off at once and cap each source point with the engine off and then start the truck and see if there is any idle change. If there is no change then the problem is elsewhere. If there was a change then put each line back one at at time to find the culprit. But the reverse would work, doesn't really matter. I would cap each port with a rubber vacuum cap, but the finger approach will work for the smaller ports I think.
Ok I am going to get the plugs. The stuff that came with my gauge is not sufficient and does not have the actual caps only plugs which are pretty much useless for what I am doing. Thanks again. Sandy
I got my caps and started capping everything off. When I got to the solenoids on the Driver side I noticed a vac line was missing from the solenoid nearest the firewall. (pic) I can't believe I never saw it but it was well hidden. My only excuse. I am not sure where it is supposed to hook up to. I think the connected port with the line goes to the TB and HVAC but not sure. I terminated the vac test until I know about this missing line.
There should be 3 vacuum solenoids, 1 larger, 2 smaller. The larger solenoid is the EGR control solenoid or EVR. The other 2 are for the AIR system, TAB= Thermactor Air Bypass and TAD = Thermactor Air Diverter. You would have to refer to a 4.9 specific vacuum diagram to see what goes where. There should be one in the engine compartment, usually on the hood or radiator support. Repair the missing line and see if your issue has been resolved.
I noticed in the picture you had caps on the vacuum ports of the solenoids. You understand that you only need to cap the vacuum sources at the manifold, right?
03-09-2017, 01:37 PM
