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Old 03-16-2011, 08:59 AM
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Hemi idle issues

Hello again,
My Hemi has been idling rough for the past few months and it seems to be getting worst and worst. It occurs when its warm or hot mostly under load or even just sitting in park.

The engine will idle down almost to the point where it will stall and then come back up again. No error codes are being thrown which makes this frustrating. I have been told it could be my EGR valve. Anyone else have a similar issue?
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Old 03-16-2011, 11:59 AM
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Re: Hemi idle issues

How many miles? Have you cleaned your throttle body? I just cleaned mine and it helped...use a little isoprobyl alcohol and a CLEAN rag/towel with minimal lint. I will be cleaning out the intake mani with some seafoam in about 1k miles...heard that helps too and others swear by the stuff. And the EGR is def another option...I am also thinking about adding a catch can, heard that helps keep our Hemi's clean!!! Hope that helps a little
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Old 03-16-2011, 12:21 PM
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Re: Hemi idle issues

In addition to mileage, what year is it? Do you know the maintenance history of it? When's the last time the plugs were changed? What type was installed? If it's an 05, have the spark plug wires ever been checked/changed?

08Hemi's right on the EGR and throttle body issues. There are other things it could be too, but let's hear about year/mileage/maintenance history first.
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Old 03-16-2011, 12:37 PM
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Re: Hemi idle issues

Quote:
Originally Posted by jeepgcoman View Post
In addition to mileage, what year is it? Do you know the maintenance history of it? When's the last time the plugs were changed? What type was installed? If it's an 05, have the spark plug wires ever been checked/changed?

08Hemi's right on the EGR and throttle body issues. There are other things it could be too, but let's hear about year/mileage/maintenance history first.

Its an 07, just turned 70k miles. I bought it with 61k miles and since then maintenance has been spotless. I had the plugs/wires changes at around 65, trans fluid and diff fluids all changed, and have been spot on every oil change.

I did call my mechanic and he mentioned that the throttle body may be the culprit too, especially because I have an K&N. He said sometimes that oil gets down in there and can cover the airflow sensor and gunk up the throttle.

So, as a first option I should just clean that out? Is there any instructions on how to do that? Im assuming you just take the tunnel off and spray up in there?
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Old 03-16-2011, 02:55 PM
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Re: Hemi idle issues

Quote:
Originally Posted by 08Hemi View Post
How many miles? Have you cleaned your throttle body? I just cleaned mine and it helped...use a little isoprobyl alcohol and a CLEAN rag/towel with minimal lint. I will be cleaning out the intake mani with some seafoam in about 1k miles...heard that helps too and others swear by the stuff. And the EGR is def another option...I am also thinking about adding a catch can, heard that helps keep our Hemi's clean!!! Hope that helps a little
Where do you get a catch can and how does it install?
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Old 03-16-2011, 04:37 PM
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Re: Hemi idle issues

Quote:
Originally Posted by noquarter View Post
Its an 07, just turned 70k miles. I bought it with 61k miles and since then maintenance has been spotless. I had the plugs/wires changes at around 65, trans fluid and diff fluids all changed, and have been spot on every oil change.

I did call my mechanic and he mentioned that the throttle body may be the culprit too, especially because I have an K&N. He said sometimes that oil gets down in there and can cover the airflow sensor and gunk up the throttle.

So, as a first option I should just clean that out? Is there any instructions on how to do that? Im assuming you just take the tunnel off and spray up in there?
Cool. NO SPRAY! Take the TB off, get some 91% isoprobyl alcohol and a clean rag...dab a little on the towel and clean both sides of the blade and housing...FYI we have a MAP sensor and an elec TB so make sure you use as little amount of cleaner needed. That's what I think happened from my K&N too, switched to an inverted-cone amsoil (dry) so I should never have that problem again!

Catch can's are available from Billet technologies, install on passenger side of the engine bay and filter the crap in the oil before it is introduced back into the engine. From what I have read this is a very good preventative maintenance mod...and helps with engine efficency!!
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Old 03-16-2011, 04:44 PM
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Re: Hemi idle issues

Do you know what kind of spark plugs they put in? If they say they changed the spark plug wires, find another mechanic, because they're ripping you off. The 07 Hemi's DO NOT have spark plug wires. They are a coil over plugs setup.

Your mileage is about right where many Hemi owners have had to change the EGR Valve. Mine, on my 06, went bad at 54K. A new valve is about $40-50 and relatively easy to change. Do you do any of your own work or always have someone do it?

Who put your K and N filter in? If it has enough oil on it to cover the Intake Air Temperature (IAT) sensor, someone doesn't know how to service it properly. There is no way there should be enough oil on the filter to foul the IAT Sensor, or anything else. You can easily check the sensor, as it is located in the intake tube near the airbox. If you clean it, be careful not to damage the sensor end. It should have a little plastic shroud around the probe. Personally, I have never seen the least bit of contamination on any one I've looked at.

Keep us posted on your findings.

The throttle body butterfly problem is caused exclusively by the inferior Chrysler Hemi Positive Crankcase Ventilation (PCV) system. A catch can is the only way I know of to easily resolve the issue. Once you have one on your vehicle, and see how much it collects (especially in damp winter months), I promise you'll be amazed. All that crap goes through the engine and combustion process and can foul the O2 sensors which, in turn, can destroy the catalytic converter(s). Check out the recent thread on O2 Sensors, and here's an excerpt by Mike, a Diablosport technician on the need for the catch can on Hemi's. He's right on.

"No, this is where I comment on lost power due to oil contamination in the intake tract/combustion chamber. I will assure you that after having seen as many logs of as many HEMIs as we have here at DiabloSport, not to mention the numerous HEMI vehicles we have had on our dyno for R&D, I can say, without a doubt, that the HEMI's PCV/Oil Vapor control is the worst of anything we deal with. All you have to do is pull your intake manifold to see the puddles of oil collected in there, and realize that it eventually gets in the combustion chamber, and oil don't like to burn, thus, detonation occurs.

There is no gimmick here. HEMI's have KR issues. The KR issues are 99% of the time contributed to by oil contamination in the intake charge, reducing the effective octane in the combustion chamber, and leading to a loss of performance.

Plenty of people have seen solid power gains on even stock vehicles when getting rid of an oil issue by adding a catch can that works properly."
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Old 03-16-2011, 07:58 PM
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Re: Hemi idle issues

Quote:
Originally Posted by noquarter View Post
I did call my mechanic and he mentioned that the throttle body may be the culprit too, especially because I have an K&N. He said sometimes that oil gets down in there and can cover the airflow sensor and gunk up the throttle....
...yeah, it's possible, but not if the K&N is serviced properly. Do not over-oil the filter element.

I have K&N drop-in in my '08 WK HEMI for the last 30K+ miles. Inspected the IAT last weekend. It's dry & clean. If your throttle body is dirty, it's because of the mixing of EGR discharge and PCV discharge in the turbulent area just behind the throttle body butterfly.

HEMI has an Intake Air Temperature (IAT) sensor and a Manifold Absolute Pressure (MAP) sensor, but no air flow sensor. IAT is in the intake silencer box and MAP is at the back end of the intake manifold. MAP sensors do get carbon crud fouled though from PCV valve oil vapor. Mechanic was probably just using a generic term.
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Old 03-18-2011, 01:27 PM
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Re: Hemi idle issues

Ok thanks for all of the solid feedback.

At this point, I am just going to bite the bullet and get a new erg valve and clean the tb. However, our dealer here wants $79 for it.

The catch can sounds interesting. Isn't that what the oil filter is supposed to do? I may just invest in a can as well. How do you maintain the can? Do you need to clean it ever oil change or something?
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Old 03-18-2011, 02:46 PM
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Re: Hemi idle issues

No, this is a totally different system. The engine oil filter just filters the engine oil. The PCV System is part of the emission system and replaces the old crankcase ventilation system that used to vent crankcase fumes into the atmosphere. With the PCV System, those fumes are now routed through the PCV Valve (really just a check valve) and back into the intake manifold and, ultimately, the combustion process . The PCV Valve is made of plastic and is not very high tolerance/quality and, even when new, will bypass oil, fumes and moisture (more in the winter months) into the intake manifold. The engine heat bakes it onto the back of the TB butterfly and, in worse case situations, if the valve is not changed regularly, causing oil puddling in the plenum and runners of the intake. You can see in my Post No. 7 above, what Mike at Diablosport says is the result.

The catch can goes in series between the PCV Valve and the intake manifold, and collects all that crud before it gets into the manifold. Normally, with in town driving, I can go about 5000-6000 miles between empties with a new valve. In the winter a lot of moisture (condensation) is introduced to the system with the oil, and you get a pretty good quantity of what some of us call, "mayonaise". As a result, I check and empty more frequently in the winter. On the highway more crankcase ventilation contaminants are generated, also requiring more frequent servicing. I took an 800 mile trip in January, emptied the can before I left and, when I got back, I was shocked to see that the 4 oz. can was full....and that was with a near new (maybe 11K on it) PCV Valve. IMO, it is well worth the investment. I've had one on my Hemi LX for over 5 years now, and the butterfly/plenum areas are still clean.
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Old 03-20-2011, 11:22 AM
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Re: Hemi idle issues

Quote:
Originally Posted by noquarter View Post
Hello again,
My Hemi has been idling rough for the past few months and it seems to be getting worst and worst. It occurs when its warm or hot mostly under load or even just sitting in park.

The engine will idle down almost to the point where it will stall and then come back up again. No error codes are being thrown which makes this frustrating. I have been told it could be my EGR valve. Anyone else have a similar issue?
ive got 55k on mine and it has the very same issue. sometimes comes about on a decline slope but also on level ground. Has only stalled once but like you said, NO error codes
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