Surging idle

Muddytazz · Nov 25, 2011

Ok, beings as I'm new to the dodge world I'm trying to learn all I can. Prior to this 97 I've solely been a chevy guy. So I'm needing help here.

Whether the 5.9 is cold or warm, sitting in park or in drive at a stop or light, the idle will surge up and down. I know this is not normal, is it just a matter of something dirty or could it be a bad part? I have NOT seen the check engine light once turn on since I bought this truck. Could it throw a code without the check engine light turning on?

Any help in me fixing this would be helpful.

bigbadram1500 · Nov 25, 2011

Anytime my truck has thrown codes, the engine light has come on first.

Muddytazz · Nov 25, 2011

Well hopefully that is eliminating a bad part theory.

Badger · Nov 25, 2011

Codes can definately be thrown without the check engine light triggering. Take it to an auto parts store and have it read. It's free to do. Also check your plenum for oil.

Muddytazz · Nov 25, 2011

This has had the plenum upgrade on it before I bought it. Would my ScanGaugeII work for checking codes?

Badger · Nov 25, 2011

Yep scanguage will work. The factory fix doesn't fix the problem forever. They just replaced the gasket. The steel plate was just reused or replaced with a new steel plate. If it was done with a Hughes plate it was done right but the gasket could still fail if installed improperly. Might as well check it since its easy to do. If that's good, and the codes read fine check all your vaccum lines and run some seafoam through it.

Muddytazz · Nov 25, 2011

How do I check the plenum thing myself?

Badger · Nov 25, 2011

Pull the intake off. Then open the butterfly on the throttle body and look in with a flashlight. It should look nice and clean. If there is any oil or residue your plenum is kaputzky and you need to do a gasket swap.

Muddytazz · Nov 25, 2011

Well that'll have to wait a while as I can't afford to have my truck down for more than a couple hours a day right now.

Badger · Nov 26, 2011

I feel ya there. It can be done in a day though.

txbass06 · Nov 26, 2011

If it doesn't show a code you could pull the TPS sensor or IAC and clean them up

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Muddytazz · Nov 26, 2011

Ok, being new to all this computer controlled, throttle bodied stuff, point me in the right direction. Pics would be great.

I'm used to running and working on carb'ed motors. Could and still can rebuild any 4 bbl to superb working order in under an hour.

txbass06 · Nov 26, 2011

Here's a pic of the TB side of the TPS

And here's where it's located. It'll be the only sensor on the drivers side of the TB

The IAC is on the back, passenger side. Not 100% sure if it's on the intake or TB but I'll snap you a couple pics tomorrow.
Easy way to check that is unplug it and see if it changes the way your truck runs. If there's no change, then there's your problem

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Mopar1973Man · Nov 26, 2011

Here is a failed plenum gasket...

Muddytazz · Nov 26, 2011

Is that looking in from the topside of the throttle body thru the butterfly's?

Badger · Nov 26, 2011

Yes it is.

Muddytazz · Nov 26, 2011

Just popped the air cleaner box off the throttle body and looked down the throat and its black in there :flame:

Was told it had the correct fix done to it. Looks like I'll be saving some money from some of the old toyota and chevy stuff I have for sale to fix it.

V-10 RAM · Nov 26, 2011

I posted a TBS in the 2nd Gen Tech Section under got my plenum plate today. My Jeep 5.9 Limited looked as if it was a blown gasket after following the TBSs it turned out to be a PCV that was letting oil pass into the manifold.
Check out the second TBS it tells how to check a leaky gasket.

Badger · Nov 27, 2011

Muddytazz said:
Just popped the air cleaner box off the throttle body and looked down the throat and its black in there Was told it had the correct fix done to it. Looks like I'll be saving some money from some of the old toyota and chevy stuff I have for sale to fix it.

Theres your sign.

V-10 RAM · Nov 27, 2011

muddytazz said:
just popped the air cleaner box off the throttle body and looked down the throat and its black in there Was told it had the correct fix done to it. Looks like i'll be saving some money from some of the old toyota and chevy stuff i have for sale to fix it.

read the tbs before you start fixing.

Surging idle

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