Engine back together VERY rough idle
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Senior User
Joined: Nov 2008
Posts: 190
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From: Broomfield, Colorado!
Engine back together VERY rough idle
Hey all.
Just got everything put back together after the rebuild. It runs great except for the idle. its bumpy and almost dies sometimes and is just really, really rough. once i start accelerating, it drives perfect though. Im on break between jobs right now so i dont have time to do any investigating until tonight, so i was hoping to get some ideas from ya'll.
So far here's my plan:
-Replace fuel filter
-clean Idle Air Control Valve(should i replace it?)
already cleaned the MAF, tried turning the idler screw up a bit. smoothed it out a little but obviously wasnt the culprit.
-I sprayed carb cleaner around at the vacuum lines, didnt find anything wrong there. only check engine code thats coming up is egr excessive. the car has always been throwing this light, i've never figured out why. all egr components had been replaced with no success at getting rid of the light.
So what does anyone think? any ideas would be great!
Thanks!
Just got everything put back together after the rebuild. It runs great except for the idle. its bumpy and almost dies sometimes and is just really, really rough. once i start accelerating, it drives perfect though. Im on break between jobs right now so i dont have time to do any investigating until tonight, so i was hoping to get some ideas from ya'll.
So far here's my plan:
-Replace fuel filter
-clean Idle Air Control Valve(should i replace it?)
already cleaned the MAF, tried turning the idler screw up a bit. smoothed it out a little but obviously wasnt the culprit.
-I sprayed carb cleaner around at the vacuum lines, didnt find anything wrong there. only check engine code thats coming up is egr excessive. the car has always been throwing this light, i've never figured out why. all egr components had been replaced with no success at getting rid of the light.
So what does anyone think? any ideas would be great!
Thanks!
Thread Starter
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Senior User
Joined: Nov 2008
Posts: 190
Likes: 1
From: Broomfield, Colorado!
Well after a bit of research i have decided it may be the intake manifold gasket leaking. mainly because the symptoms seem to match, and there is a hissing noise.
If i spray some carb cleaner on it, the rpms should rise for a moment, correct?
If i spray some carb cleaner on it, the rpms should rise for a moment, correct?
Logistics Pro
Joined: Jun 2009
Posts: 4,816
Likes: 83
From: Cedar Rapids, IA
Yep. Your symptoms are consistent with a vacuum leak. Before disassembling the intake you may want to fist make sure the intake air tubing between the MAF sensor and the throttle body is properly connected and not cracked.
-Rod
-Rod
Thread Starter
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Senior User
Joined: Nov 2008
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From: Broomfield, Colorado!
Update: Sprayed along all vacuum lines AGAIN, 2 times actually. sprayed all around intake (hissing noise was from intake), cleaned IAC(was humming as it had before when i had issues with it).
What on EARTH could be going wrong here? i'm at the point where i may just take it to the shop for diagnosis, but would hate to do so.
What on EARTH could be going wrong here? i'm at the point where i may just take it to the shop for diagnosis, but would hate to do so.
Junior User
Joined: Dec 2010
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I had the same thing and sprayed carb cleaner everywhere with no RPM change. Finally replaced the intake gaskets and magically, no more problem. You can not think that carb cleaner will reveal all vacuum leaks. It doesn't.
Thread Starter
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Senior User
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From: Broomfield, Colorado!
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Logistics Pro
Joined: Jun 2009
Posts: 4,816
Likes: 83
From: Cedar Rapids, IA
Do you happen to have access to a scan tool with datastream mode so you can monitor various sensors and parameters to identify one or two that are not responding like they should? Maybe you have a lazy fuel injector, and out of range engine coolant temperature sensor, or some other sensor that is unplugged.
-Rod
-Rod
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Thread Starter
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Senior User
Joined: Nov 2008
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From: Broomfield, Colorado!
Ya i have a craftsmen scan tool with live data. im thinking i may take the intake off and inspect it. i have an appointment at the auto shop on tuesday, but i would like to avoid the fees from that if i can identify the issue. the symptoms just sound so indicative of an intake manifold leak that i cant stop thinking that its the issue.
one thing im questioning is that the gasket i got for the lower intake looks like the one in this set:
Buy Felpro Intake Manifold Gasket Set MS 98005 T at Advance Auto Parts
but the one in this set:
Buy Felpro Intake Manifold Gasket Set MS 95739 at Advance Auto Parts
looks more like what my chilton manual showed. im thinking maybe the bead of RTV where it specified (Apply RTV silicone gasket material at the junction points of the heads and manifold.) may not have been enough.
Do you think this may be a cause of my issue?
one thing im questioning is that the gasket i got for the lower intake looks like the one in this set:
Buy Felpro Intake Manifold Gasket Set MS 98005 T at Advance Auto Parts
but the one in this set:
Buy Felpro Intake Manifold Gasket Set MS 95739 at Advance Auto Parts
looks more like what my chilton manual showed. im thinking maybe the bead of RTV where it specified (Apply RTV silicone gasket material at the junction points of the heads and manifold.) may not have been enough.
Do you think this may be a cause of my issue?
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