93 5.2 Magnum stumbles off idle. I'm stumped
#2984599
11/12/21 06:43 PM
11/12/21 06:43 PM
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Joined: Feb 2006
Posts: 1,179 Canada
demon
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super stock
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OP
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Canada
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My 1993 5.2 Magnum automatic has developed an off idle stumble. Last year I had the intake off and replaced the plenum gasket, and did routine maintenance. Drove it for months since with no issues. Lately, it often stumbles and stalls when barely touching the gas pedal. Especially when warmed up, and parking, or going between Drive and Reverse. Doesn't happen when engine is cool. I have removed and cleaned the throttle body thoroughly. Tried swapping the sensors on the throttle body with used sensors from another running 5.2. Replaced the O2 sensor with a new one. Replaced the PVC valve. Checked vacuum lines. No change. Still wants to stumble and quit. What am I missing?
Last edited by demon; 11/12/21 06:44 PM.
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: mgoblue9798]
#2984612
11/12/21 07:30 PM
11/12/21 07:30 PM
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Joined: Feb 2006
Posts: 1,179 Canada
demon
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Remove and clean the idle air control valve from the back of the throttle body if you haven't done so already. I have done that twice, and even swapped it with another used one. But I guess it's possible I have two faulty ones? When it's out, I can push the plunger in, but it stays in. Not sure if that is normal
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: demon]
#2984626
11/12/21 07:53 PM
11/12/21 07:53 PM
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Joined: Mar 2010
Posts: 1,061 Atlanta, GA
mgoblue9798
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super stock
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Atlanta, GA
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Remove and clean the idle air control valve from the back of the throttle body if you haven't done so already. I have done that twice, and even swapped it with another used one. But I guess it's possible I have two faulty ones? When it's out, I can push the plunger in, but it stays in. Not sure if that is normal Next thing I would do is start spraying some starting fluid around while the engine is idling to look for a vacuum leak. If that doesn't work it is time to find out if it is spark or fuel causing your problem. I am assuming you don't have any error codes when you do the key dance correct? BTW when you swap IAC's it can take a bit for the computer to adjust. I just put a used on on my 5.9. It was running at high idle for a couple days even after being plenty warmed up, and finally today decided to act right and went into low idle after warming up.
Last edited by mgoblue9798; 11/12/21 07:55 PM.
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: poorboy]
#2984656
11/12/21 09:25 PM
11/12/21 09:25 PM
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Joined: Mar 2010
Posts: 1,061 Atlanta, GA
mgoblue9798
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super stock
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Atlanta, GA
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My 96 5.2 only has 44,000 miles on it. I got a stumble off idle with it as well. Used air valves didn't help. I finally sprung for a new valve and the problem went away. It was the best money I've spent in a while. It wasn't an original Mopar part (would you really still expect to find real Mopar parts?), so I may have to change it before it gets 25+ years old, but I'm OK with that.
After the new valve fixed the problem, I took a really good look at my original valve. I could see a difference in the color of the aluminum around the plunger in one area. I suspect the aluminum has worn away over time, because miles sure wasn't the cause.
Of course I'm assuming you have replaced the spark plugs, cap, rotor and ignition wires... Gene I think Delphi was the manufacturer for Dodge. They are available from rock auto. The 12 buck chinese ones though you may as well just flush your money down the toilet and save yourself the trouble.
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: mgoblue9798]
#2984717
11/13/21 02:16 AM
11/13/21 02:16 AM
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Joined: Jan 2004
Posts: 8,233 fredericksburg,va
cudaman1969
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Change the CRANK sensor, I chased my tail for two years changing out everything, injectors, TB, wires-caps-plugs, mapp sensor, TPS, you name it including the pan under the intake. Never changed the crank sensor because it looked NEW. While getting another TB at the pic a part I got a well used sensor off the 5.9 engine on a whim put it on and has run GREAT ever since. Don’t get Aftermarket crap, get factory parts. BTW it would run good until a medium load on the engine. Also changed out both o2 sensors, catalytic converter, water temp sensors, distributor, there’s more just can’t remember all of the stuff. Now the lock up converter broke, 25,000 miles on a complete trans overhaul. Just about ready to set it on fire.
Last edited by cudaman1969; 11/13/21 02:26 AM.
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: demon]
#2984857
11/13/21 03:26 PM
11/13/21 03:26 PM
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Joined: Jan 2004
Posts: 8,233 fredericksburg,va
cudaman1969
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master
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fredericksburg,va
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I dont think Magnums have a EGR (beer keg intake)
Last edited by cudaman1969; 11/13/21 03:27 PM.
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: cudaman1969]
#2984882
11/13/21 05:18 PM
11/13/21 05:18 PM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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I Live Here
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I dont think Magnums have a EGR (beer keg intake) The early ones did and i just fixed one doing exactly this by putting a block off plate under it. It was in a van so very easy to see the pintle move, just the very slightest throttle movement and the valve would open all the way up.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: HotRodDave]
#2984917
11/13/21 07:42 PM
11/13/21 07:42 PM
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Joined: Feb 2006
Posts: 1,179 Canada
demon
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OP
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Canada
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I dont think Magnums have a EGR (beer keg intake) The early ones did and i just fixed one doing exactly this by putting a block off plate under it. It was in a van so very easy to see the pintle move, just the very slightest throttle movement and the valve would open all the way up. Unfortunately on my W150, it is right against the firewall and very difficult to access
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: demon]
#2985029
11/14/21 07:56 AM
11/14/21 07:56 AM
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Joined: Jan 2006
Posts: 8,162 USA
360view
Moparts resident spammer
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Moparts resident spammer
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Posts: 8,162
USA
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I dont think Magnums have a EGR (beer keg intake) The early ones did and i just fixed one doing exactly this by putting a block off plate under it. It was in a van so very easy to see the pintle move, just the very slightest throttle movement and the valve would open all the way up. Unfortunately on my W150, it is right against the firewall and very difficult to access To diagnose whether the EGR on 1992-1995 Magnums is causing your stumble you can also disconnect and block the steel EGR tubing that runs over to and connects to the exhaust manifold. Considering the age and rust of that tube connection, it might be quicker and easier to just cut the tube then repair it afterwards with a sleeve or two new fittings. I have been thinking of experimenting with a “cooled EGR modification: Using ten feet of corrosion resistant CuNiFer tubing to pick up exhaust gas way back behind the muffler. The exhaust gas cools in the exhaust pipes and muffler, and would cool more travelling forward in the CuNiFer tubing. I would use straight lengths of CuNiFer so I could “rod out” carbon build up. Cooled EGR reduces pre-ignition, reduces NOx, allows use of lower Octane fuel, and can improve fuel economy. The brake lines of my 1995 Ram have already been replaced with CuNiFer brake lines 6 years ago. CuNiFer metal is an alloy of Copper, Nickel and Iron that is easily bent without kinks and is nearly as corrosion resistant as stainless steel.
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: 360view]
#2985033
11/14/21 08:59 AM
11/14/21 08:59 AM
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Joined: May 2019
Posts: 6,221 nowhere
Sniper
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Cooled EGR reduces pre-ignition, [color:#FF6666]as does regular EGR[/color reduces NOx, [color:#FF6666]as does regular EGR[/color allows use of lower Octane fuel, [color:#FF6666]as does regular EGR[/color and can improve fuel economy. [color:#FF6666]as does regular EGR[/color
So what's the benefit of cooled EGR over regular EGR? In a vary narrow arena not applicable to the OP's setup there might be slight improvements in the listed areas IF the computer has the capacity to take advantage of it, doubtful the stock setup does. https://www.sae.org/news/2014/09/cooled-egr-shows-benefits-for-gasoline-engines
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Re: 93 5.2 Magnum stumbles off idle. I'm stumped
[Re: Sniper]
#2985322
11/15/21 12:50 AM
11/15/21 12:50 AM
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Joined: Jan 2005
Posts: 12,419 Kalispell Mt.
HotRodDave
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I Live Here
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Kalispell Mt.
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Cooled EGR is more detonation resistant as it does not heat up the intake as much as it does on something like the magnum where it picks it right out of the hot exhaust manifold and dumps it immediately back into the magnums already too hot intake.
The other reason I would think would be more important picking it up so far back is that after the cat there is much less unburned hydrocarbons to clog it up, this would save diesel owners in particular a ton of headache as they get clogged with carbon pretty quick.
I still am convinced it causes a drop in MPG cooled or not... you have to pump more volume of gasses through the engine, it is a pumping loss. Also slows down the burn requiring earlier ignition timing witch means more negative work on the crank. Also since the air and fuel molecules are now further apart with innert gas molecules separating them less of them are gonna burn and produce power. I feel it is and should only be considered an emissions control device, every car I have blocked it on saw an immediate improvement in MPG. The only way I could fathom it helping is if your fuel octane level was too low for your engine.
I am not causing global warming, I am just trying to hold off a impending Ice Age!
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