86customanche Posted August 3, 2015 Share Posted August 3, 2015 This HOSE (wire) is from the firewall on the passenger side and is not connected, where does it go?The engine starts, runs ok for a few seconds, then very rough, rpm drops to a couple hundred, then either cuts off or returns to normal. Sounds like a missing cylinder for a few moments. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted August 3, 2015 Share Posted August 3, 2015 It's not a wire. It's a vacuum hose. It should be plugged in to the heater control valve in the lower right of your picture. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted August 3, 2015 Share Posted August 3, 2015 It's not a wire. It's a vacuum hose. It should be plugged in to the heater control valve in the lower right of your picture. :agree: When you turn on your heat from the inside of the truck, this vacuum hose recieves vacuum which pulls open the heater core valve. This allows coolant to flow through your heater core thus giving you heat flowing through your vents. Link to comment Share on other sites More sharing options...
86customanche Posted August 3, 2015 Author Share Posted August 3, 2015 Thanks, I've reattached the HOSE in the proper spot. Link to comment Share on other sites More sharing options...
docivy Posted August 3, 2015 Share Posted August 3, 2015 Any difference in the idle problem with it attached Link to comment Share on other sites More sharing options...
86customanche Posted August 4, 2015 Author Share Posted August 4, 2015 I had already pulled the plugs (see picture) when I discovered the disconnected hose. If that tiny hose could cause the problem I'm having then certainly it should have been better attached, i.e. Clamped, tied, screwed into place. But indeed a good question, but I'll probably go ahead and install the new plugs before the next attempt to run it. Link to comment Share on other sites More sharing options...
docivy Posted August 4, 2015 Share Posted August 4, 2015 A vacuum leak will with no doubt cause running issues Link to comment Share on other sites More sharing options...
86customanche Posted August 5, 2015 Author Share Posted August 5, 2015 With new plugs it still has difficulty running smooth and usually cuts off. Link to comment Share on other sites More sharing options...
1989 Eliminator Posted August 5, 2015 Share Posted August 5, 2015 Check the following vacuum hoses: MAP vacuum hose going from MAP sensor to throttle body. Vacuum lines running along the passenger side of the engine compartment to the passenger side front bumper. There is a vacuum bottle up front there and if any of those lines are cracked/broken then that is obviously an issue. Vacuum line going from fuel pressure regualtor to intake manifold. Vacuum line going from intake manifold to EGR valve. Vacuum line going from intake manifold to cruise control (if equipped). I personally moved my vacuum bottle from the passenger side front bumper to just under my coolant bottle by the firewall. I then cut the vacuum lines shorter. Shorter lines means less possibility of a vacuum leak. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted August 5, 2015 Share Posted August 5, 2015 You might want to do a go 'round on your vacuum lines. Especially the ones on the drivers side. The HVAC line, cruise, and CAD lines don't have a lot of effect on the running, more so the big one off the manifold, MAP to TB, EGR (if it's still there) and brake booster will have large effect on the engine. Any open vac ports on the manifold will definitely cause issues. What you're explaining reminds me of a MAP sensor (or the line to it) that can make your engine run like crap. If you have any cracked, cut, broken, chafed or otherwise compromised vac lines, they should be replaced. Grommets on the VC as well need to be newish and tight. The vacuum harness is cheap enough to replace, and bulk vac line is super cheap for all the other connections. Link to comment Share on other sites More sharing options...
86customanche Posted August 5, 2015 Author Share Posted August 5, 2015 Thanks for the suggestions. Need to learn what CAD, MAP, TB, EGR, VC, etc... are. (Note, Dad here trying to get the truck running to exercise it every couple of weeks while owner son is out of state for a few years). Link to comment Share on other sites More sharing options...
outlaw star Posted August 5, 2015 Share Posted August 5, 2015 Thanks for the suggestions. Need to learn what CAD, MAP, TB, EGR, VC, etc... are. (Note, Dad here trying to get the truck running to exercise it every couple of weeks while owner son is out of state for a few years). CAD: Central Axle Disconnect or Control Arm Drop MAP: Manifold Absolute Pressure TB: Throttle Body or TBI: Throttle Body Injection (depends on which engine) EGR: Exhaust Gas Recirculation VC: Vacuum Canister I believe there was a thread somewhere in here that lists all the abbreviations. Link to comment Share on other sites More sharing options...
86customanche Posted August 6, 2015 Author Share Posted August 6, 2015 It's running better now, or at least for the 15 seconds I ran it. I actually had to use the key to turn it off! I pulled all the vacuum hoses and checked for blockage and cracks. I removed and cleaned the idle air control (IAC) valve; it was very dirty. Link to comment Share on other sites More sharing options...
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