Rough Idling

PJalbanesi

Member
Mar 31, 2017
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I recently removed my intake manifold m, throttle body egr spacer and all that good stuff to remove my valve covers and after putting everything back together when starting the car it idles high when first started then casually surging up and down, anyone know what I could of done wrong??
 

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I hooked up the two hoses on the manifold and I put new gaskets on the manifold and throttle body idk where the leak could be coming from

I only responded to you because this same exact thing happened to my friend awhile back and it turned out he had his intake spacer installed wrong...
this caused a leak. I know you didn't mention anything about a spacer but I figured it was a similar situation anyway as he was installing valve covers as well.

Ended up with the same symptoms as you. He had to remove everything and retrace his steps.
 
There are ways to identify a vacuum leak, which require spraying some fluid (starter?) and see if the idle changes. I am not an expert mechanic or anything but I have managed to keep my car running since 96. Hopefully someone else can come in and chime in
 
You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. It includes how to dump the computer codes quickly and simply as one of the first steps. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix. :D

It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 250,000 hits, which indicates it does help fix idle problems quickly and inexpensively.
 
Did you remove just the upper or also the lower intake

IF just the upper
did you repace the upper to lower intake plenum gasket
did you torque down the bolts properly and go back and retorque them after a heat cycle
did you hook up all the vacum lines

If you removed the lower
did you let the lower intake setup before you torqued it down
did you go back over the bolts several times to ensure accurate torque
did you put some spray tack or RTV on the intake gaskets to make sure they did not slip
 
I only responded to you because this same exact thing happened to my friend awhile back and it turned out he had his intake spacer installed wrong...
this caused a leak. I know you didn't mention anything about a spacer but I figured it was a similar situation anyway as he was installing valve covers as well.

Ended up with the same symptoms as you. He had to remove everything and retrace his steps.
Thanks for the advoce, my thermometer gasket was ripped on the top replaced it and she runs like a champ
 
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