No idle after lower intake manifold gasket replacement
01-20-2009, 07:30 PM
#1
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Thread Starter
No idle after lower intake manifold gasket replacement
I just got done installing new upper and lower intake manifold gaskets on my 90 F150. While installing the upper intake manifold I sprayed the throttle body and IAC out with carb cleaner. When we tried to start it up it just idles for a second then stalls. Also, the truck used to pop right off with no need to give it gas. Now I must work the throttle to get it to start. The fuel pump is running and the truck is timed correctly (or as close as possilbe with a poor idle) at 10* BTDC with the jumper removed. The truck ran 100% before the install so I'm under the impression that I messed something up with the TPS or IAC by blasting it with carb cleaner. The truck runs great above idle, but I must keep my foot on the gas to keep it running (fun with a manual trans). Thanks in advance for any advice!
01-20-2009, 08:52 PM
#3
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Did you get the throttle linkage put back correctly, or forgot the gasket under the IAC? It just seems like Its something small and easy to miss. Just enough to annoy you. sounds like something I would do! Keep tryin dude, It can't be to bad.
01-20-2009, 09:21 PM
#4
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I hope it's just something simple. I checked the plug and its fully connected. There is a new gasket on the IAC (just checked that earlier too lol). The resistance of the IAC was about 8 ohms, which is supposed to be in spec according to autozones repair guide. I'm wondering if the IAC is stuck closed cause if memory serves me right, when I sprayed carb cleaner into the throttle body, no cleaner (or very little) leaked past the butterflies until I opened them manualy. If the IAC is stuck in the closed position the engine would starve for air and die. This project is beginning to be an expensive learning experience 
Thanks for the quick responses guys!!! 
Thanks for the quick responses guys!!!
01-20-2009, 10:15 PM
#5
Senior Member
Does the truck idle on it's own after it gets warmed up? (20-30 seconds)
If not, then the IAC is probably not your problem. It should start and idle with the IAC unplugged. Have you checked to make sure the butterflies are moving? The cleaner might have loosened up some gunk that gelled up again and stuck them shut.
If not, then the IAC is probably not your problem. It should start and idle with the IAC unplugged. Have you checked to make sure the butterflies are moving? The cleaner might have loosened up some gunk that gelled up again and stuck them shut.
01-21-2009, 07:49 AM
#6
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No, I drove the truck last night and it won't start or idle on its own hot or cold. I drove it around for about a half an hour last night to get it warmed up and evaporate any carb cleaner left. It runs fine with a little throttle but let off and it sputters and dies. 
I'm going to try and check the codes tonight after work.
I'm going to try and check the codes tonight after work.
01-21-2009, 06:00 PM
#7
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Thread Starter
He's fixed!!!
I went out after work to make sure the IAC worked and that the throttle body was clear of gunk. I started the truck and was looking around the engine compartment and had one of those gut fealings (not the kind you have after too many beers). Anyway I thought the vacuum line running to the EGR looked off so I pulled it and the motor smoothed right out and ran great. Turns out I installed the green vacuum line onto the blower box to the right and installed the line to the blower box onto the EGR. Swapped the two lines and now she runs great. Thank you oneFITTYman and aliens8mycow for your help!!! 
