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Discussion Starter #1 (Edited)
Rough idle and SES light after intake manifold replacement

Hi all,

Intake manifold, all appropriate gaskets, plugs, plug wires, T-stat, and injector O-rings replaced about 8 weeks ago. Engine ran fine until about 2 weeks ago, when rough idle started and SES light simultaneously came on. I replaced IAC twice, but rough idle and SES light came back within a couple days. Engine otherwise runs smooth as silk; no problems. Any thoughts? Haven't yet pulled any codes.
 

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Could be a vacuum leak or egr malfunction, maf malfunction, etc. Once you pull the codes you should have a pretty good idea. Did you retorque the manifold after a heat cycle?
 

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Without pulling the code, you are just guessing. I learned the hard way on that one before.

Did you retorque the manifold after a heat cycle?
First I heard of this. Then again, people are re-torquing everything these days, a little excessive if you ask me. I bet a lot of mechanics don't even torgue them in the first place, so as long as they were torqued on install, you are ahead of the game.

Al
 

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Hi all,
... etc ... rough idle started and SES light simultaneously came on. ... etc ... Engine otherwise runs smooth as silk; no problems. Any thoughts? Haven't yet pulled any codes.
I have no idea what year your car is ... but when my 1995 did that I found it to be the tee in the vacuum line that operates the EGR, hole melted opposite the side leg. Dorman replacement and I added a shield behind it .... and I have a spare now in the glove box. http://forums.tccoa.com/7-engine-4-6l-5-4l/142542-vacuum-line-replacement-article.html#post1818514

Now, my '92 ..... did need a new IAC, but that's a different apple. :smile2:
 

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Discussion Starter #5
Could be a vacuum leak or egr malfunction, maf malfunction, etc. Once you pull the codes you should have a pretty good idea. Did you retorque the manifold after a heat cycle?
Pulled the code. Said it's the egr management valve. Looks like the vacuum hose to it is dried out/cracked. Could be the problem. Damnedest thing, though...SES light stopped glowing yesterday driving home from work without my fixing anything. Now idles fine again. WTF??!!
 
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