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Discussion Starter · #1 ·
I've got a 2010 SE V-6 Challenger that has developed a weird problem recently.
When sitting at stop lights the Throttle control will drop into "limp mode" and the warning lights on the dash for it and the traction control system will come on. I have to turn the ignition off and re-start the car and the problem will disappear.
It happens at random times but always at an idle. I checked for codes but there are no stored codes in the computer. I've checked online for troubleshooting and info on what component could be failing but I have come up with nothing and I am at a loss on where to go from here.
anyone familiar with this issue and how to correct it?
 

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The Bacon Hauler (‘12 Cop Charger)
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How many miles on the car?

My first thought is one of the ABD speed sensors in the wheels is dying or slowly losing the ability to report valid voltage to controlling module. The computer requires all 4 sensors report data, and if less than 4 report, it will force LIMP mode since it cannot adequately manage ABS without all the sensors’ data.

Without more details, that’s the best guess I can offer. Further diagnosis will require more testing, tinkering, or parts swapping to continue troubleshooting deeper.
 
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Discussion Starter · #3 ·
How many miles on the car?

My first thought is one of the ABD speed sensors in the wheels is dying or slowly losing the ability to report valid voltage to controlling module. The computer requires all 4 sensors report data, and if less than 4 report, it will force LIMP mode since it cannot adequately manage ABS without all the sensors’ data.

Without more details, that’s the best guess I can offer. Further diagnosis will require more testing, tinkering, or parts swapping to continue troubleshooting deeper.
I can see what you're describing, that would explain the traction control portion but how/why would that affect the Throttle Control System?

The car has 112k, new engine installed last year (7k ago) and has been trouble-free until this started. It has also occurred a couple of times after 30-35 miles of highway driving and I have to pull over, shut it down and wait 10-15 seconds, then it restarts normally and all is well for a awhile.
 

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The Bacon Hauler (‘12 Cop Charger)
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I can see what you're describing, that would explain the traction control portion but how/why would that affect the Throttle Control System?

The car has 112k, new engine installed last year (7k ago) and has been trouble-free until this started. It has also occurred a couple of times after 30-35 miles of highway driving and I have to pull over, shut it down and wait 10-15 seconds, then it restarts normally and all is well for a awhile.
Was the ETC light flashing or continuously illuminated when it came on?

Do you have a list of active/stored DTCs?

There is something called the ETC RELEARN function that the dealership can use their equipment to command the PCM to go through (non-dealership shops maybe can do the same, I don’t know, they would have to know about it though to try it). The engine replacement likey qualifies as one of the scenarios under which that procedure is prescribed to make sure the new components behave nicely with their new home.

Following the service manual’s procedures for diagnosing the active DTCs related to this would rule it out or resolve it if it’s the underlying problem. Most of those start with “diagnose other DTCs first and then do this one <relevant ETC code>“. So that’s why a complete list of the current DTCs is pertinent here.

Also, there are a few different variants/configurations of 3.5L out there. Do you know the donor vehicle’s make and model from your replacement engine? It’s possible this car’s PCM needs to be reprogrammed to handle the engine and its sensors from a different vehicle if that donor vehicle’s PCM was sufficiently different from yours.
 

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The Bacon Hauler (‘12 Cop Charger)
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FYI

1010428
 

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Discussion Starter · #6 ·
Was the ETC light flashing or continuously illuminated when it came on?

Do you have a list of active/stored DTCs?

There is something called the ETC RELEARN function that the dealership can use their equipment to command the PCM to go through (non-dealership shops maybe can do the same, I don’t know, they would have to know about it though to try it). The engine replacement likey qualifies as one of the scenarios under which that procedure is prescribed to make sure the new components behave nicely with their new home.

Following the service manual’s procedures for diagnosing the active DTCs related to this would rule it out or resolve it if it’s the underlying problem. Most of those start with “diagnose other DTCs first and then do this one <relevant ETC code>“. So that’s why a complete list of the current DTCs is pertinent here.

Also, there are a few different variants/configurations of 3.5L out there. Do you know the donor vehicle’s make and model from your replacement engine? It’s possible this car’s PCM needs to be reprogrammed to handle the engine and its sensors from a different vehicle if that donor vehicle’s PCM was sufficiently different from yours.
Thanks for the reply; the light is on continuously when it happens.
There are no codes displayed or stored when I hook up a scanner. That is what has me scratching my head, I have no idea where to start looking.
The engine is an ATK replacement long block, all other components and peripherals are original to the car with the exception of new sending units when the new long block went in,i.e. oil pressure, water temp.
 

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The Bacon Hauler (‘12 Cop Charger)
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Thanks for the reply; the light is on continuously when it happens.
There are no codes displayed or stored when I hook up a scanner. That is what has me scratching my head, I have no idea where to start looking.
The engine is an ATK replacement long block, all other components and peripherals are original to the car with the exception of new sending units when the new long block went in,i.e. oil pressure, water temp.
What is the condition of the charging system and battery? Any recent problems with the alternator or a bad battery?

How old is the battery; what do its terminal connections look like?

Has the chassis to battery ground cable been messed with lately? Make sure it is still bolted down firmly to the battery and to the body just behind it and next to the rear fuse box.
 
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Discussion Starter · #8 ·
What is the condition of the charging system and battery? Any recent problems with the alternator or a bad battery?

How old is the battery; what do its terminal connections look like?

Has the chassis to battery ground cable been messed with lately? Make sure it is still bolted down firmly to the battery and to the body just behind it and next to the rear fuse box.
@Nuke Sorry about the delay in replying. I had a well-house problem come up and I've been full-time on it.

Okay, the battery is less than a year old and shows fully charged, terminals are clean with no corrosion and tight. Chassis ground is firmly attached with no signs of corrosion ( I also inspected the engine-to-chassis grounds, all good there as well).
I hadn't started of driven the car in a week until today- in the past the light on the dash and the "limp mode" have always occurred after driving awhile- but when I started it this morning, the car was only idling about 20-30 seconds before it happened. As before, shutting off the car, waiting a few seconds and restarting cleared it up and the car ran fine again. I grabbed my code reader and still have no current or stored codes.

Any help is appreciated.
 

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The Bacon Hauler (‘12 Cop Charger)
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@Nuke Sorry about the delay in replying. I had a well-house problem come up and I've been full-time on it.

Okay, the battery is less than a year old and shows fully charged, terminals are clean with no corrosion and tight. Chassis ground is firmly attached with no signs of corrosion ( I also inspected the engine-to-chassis grounds, all good there as well).
I hadn't started of driven the car in a week until today- in the past the light on the dash and the "limp mode" have always occurred after driving awhile- but when I started it this morning, the car was only idling about 20-30 seconds before it happened. As before, shutting off the car, waiting a few seconds and restarting cleared it up and the car ran fine again. I grabbed my code reader and still have no current or stored codes.

Any help is appreciated.
Very strange...according to that snippet from the service manual I pasted above, the illumination of the light on the dash should be accompanied by a DTC stored in the PCM, assuming the light is illuminated to a perceived problem and not part of a self-test.

When this occurs and while the light remains on, does the car’s drivability suffer, or is it just a warning light on the dash that doesn’t seem to be tied to any off-nominal behavior?
 

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Discussion Starter · #10 ·
Very strange...according to that snippet from the service manual I pasted above, the illumination of the light on the dash should be accompanied by a DTC stored in the PCM, assuming the light is illuminated to a perceived problem and not part of a self-test.

When this occurs and while the light remains on, does the car’s drivability suffer, or is it just a warning light on the dash that doesn’t seem to be tied to any off-nominal behavior?
Thanks for the reply, Nuke.
Oh no, it isn't just a light on the dash when it happens. The engine feels like it has a miss or fouled plug and throttle response is almost non-existant; I have to immediately pull over, it isn't drive-able. Also, as I mentioned in the original post, the ESP (traction control?) light on the dash comes on as well. I can't think of anything that would affect both of those system simultaneously. I'm completely stumped.
 

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The Bacon Hauler (‘12 Cop Charger)
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Thanks for the reply, Nuke.
Oh no, it isn't just a light on the dash when it happens. The engine feels like it has a miss or fouled plug and throttle response is almost non-existant; I have to immediately pull over, it isn't drive-able. Also, as I mentioned in the original post, the ESP (traction control?) light on the dash comes on as well. I can't think of anything that would affect both of those system simultaneously. I'm completely stumped.
An undercharged/dying battery or alternator could result in strange bedfellows like that, but you sound pretty sure they are good. So I would break this up into pieces, diagnose the ETC side first.

But that isn’t going to be so easy either it sounds like. Those symptoms and the ETC warning light happening together would have to coincide with at least one DTC being stored in the PCM, that’s virtually guaranteed. Diagnosing this without the DTC(s) will be very difficult. So figuring out why you can’t see or retrieve the codes in the PCM should probably be the first part of this that gets addressed. Otherwise you’re kinda flying blind...

What kind of ODBII device do you have to connect to the car and read the DTCs?

What about a sure-fire test to make sure it can retrieve codes? (E.g. unplug the throttle body wiring harness connector and then start the car. That should immediately set a retrievable DTC)
 

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Discussion Starter · #12 ·
Hey @Nuke, I've been working on the car for the last week when I've had time. Changed oil, filter, and new air filter and did an inspection- trying to find a pinched wire or loose connection or anything that might account for my problem. I did find an intake leak at the EGR tube/plenum joint; the blue silicone(?) seal was torn and it was sucking air badly. Started it up after the repair and I had a check engine light. Plugged in the reader and got a code P0406. I cleared the code, re-started the engine and the light was gone. This has happened 2-3 times in the last year, I've concluded that the EGR Valve is sticking periodically. (It also tells me the computer is setting and storing DTC's).
I took it out for a drive and it was fine, no issues in 50 miles. I've driven it every day for 5 days as of today and the throttle control issue has not re-occurred.
Now I'm really puzzled- could an intake leak cause the throttle control system to act up like that?
 

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The Bacon Hauler (‘12 Cop Charger)
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Hey @Nuke, I've been working on the car for the last week when I've had time. Changed oil, filter, and new air filter and did an inspection- trying to find a pinched wire or loose connection or anything that might account for my problem. I did find an intake leak at the EGR tube/plenum joint; the blue silicone(?) seal was torn and it was sucking air badly. Started it up after the repair and I had a check engine light. Plugged in the reader and got a code P0406. I cleared the code, re-started the engine and the light was gone. This has happened 2-3 times in the last year, I've concluded that the EGR Valve is sticking periodically. (It also tells me the computer is setting and storing DTC's).
I took it out for a drive and it was fine, no issues in 50 miles. I've driven it every day for 5 days as of today and the throttle control issue has not re-occurred.
Now I'm really puzzled- could an intake leak cause the throttle control system to act up like that?
The EGR setup on those engine has to be the best example I’ve ever seen of what happens when you feed a bunch of monkeys hard liquor and then turn them loose with crayons and paper to design emission components, because a pack of drunken primates is the only entity I can think of that would consider that a good way to implement EGR. Nevertheless, it’s what you’re stuck with, so you have to deal with it...

As far as leaks at that tube inlet on the back of the plenum, that thing will leak every time that plenum is removed and then reinstalled. It’s a virtual guarantee. Back when I had my 2010 Challenger with the 3.5L, I ended up using red RTV on that tube inlet to seal it off and stop leaks. That actually seemed to work pretty good...much better than the standard gasket/o-ring and seal anyway.

If that inlet tube had a bad leak, that might account for the code you retrieved, but I can’t imagine it was the cause of the original problem you described.

Regarding the original problem, I am wondering if it’s a result of the accelerator position sensors disagreeing with each other, throwing the computer for a loop. Although I would expect that to result in a DTC being set to indicate the perceived problem, but whatever, stranger things and all that.


Do a throttle recalibration and see if that has any effect:

1. Turn ignition to Run without starting engine and wait for all the dash warning lights to go out.
2. In one slow, steady motion, depress the accelerator all the way to the floor, and release it in the same slow, steady motion.
3. Turn ignition to Off.

The throttle sensors should now be aligned with each other. Start car and drive it around to see if any difference is felt and also to check for the orig to resurface.

If the problem continues after that procedure is performed, a new(er) throttle body or a new(er) accelerator pedal may be needed to fix it. Those could likely be checked by logging the related PIDs from the PCM and watching for discrepancies. If the accelerator position PID says one thing while the throttle body position sensor says another, I would begin to suspect the TB is slowly dying or the accelerator pedal assembly is on its way out. A resistance test of each might help narrow down the culprit.
 

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Discussion Starter · #14 ·
The EGR setup on those engine has to be the best example I’ve ever seen of what happens when you feed a bunch of monkeys hard liquor and then turn them loose with crayons and paper to design emission components, because a pack of drunken primates is the only entity I can think of that would consider that a good way to implement EGR. Nevertheless, it’s what you’re stuck with, so you have to deal with it...

As far as leaks at that tube inlet on the back of the plenum, that thing will leak every time that plenum is removed and then reinstalled. It’s a virtual guarantee. Back when I had my 2010 Challenger with the 3.5L, I ended up using red RTV on that tube inlet to seal it off and stop leaks. That actually seemed to work pretty good...much better than the standard gasket/o-ring and seal anyway.
Drunken monkeys! Thanks, I blew coffee all over the screen when I read that! It is an accurate description of the engineering, I've got to agree. The EGR opening in the plenum and upper end of the tube were covered in a heavy coat of red RTV when I got the car so I guess that is the 'go-to' fix for it. Even though I just put in a new gasket/seal I'll give it a good slathering of RTV just to be sure it won't happen again.
I know the damned tube isn't bent correctly to align with the opening and the $70 OEM replacement tube I bought when I installed the new engine last year was no better. They couldn't make it just a little bit flexible for alignment? Sheesh. And it's just one of several asinine engineering foul-ups on this engine; don't get me started on the coolant line under the lower intake manifold or the valve-train clatter in these engines!

I'll do the recalibration and run the tests you advised if the problem occurs again, everything is working fine right now, no re-occurrence in 6 days now.

Thanks for the assistance and patience @Nuke !
 

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The Bacon Hauler (‘12 Cop Charger)
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Drunken monkeys! Thanks, I blew coffee all over the screen when I read that! It is an accurate description of the engineering, I've got to agree. The EGR opening in the plenum and upper end of the tube were covered in a heavy coat of red RTV when I got the car so I guess that is the 'go-to' fix for it. Even though I just put in a new gasket/seal I'll give it a good slathering of RTV just to be sure it won't happen again.
I know the damned tube isn't bent correctly to align with the opening and the $70 OEM replacement tube I bought when I installed the new engine last year was no better. They couldn't make it just a little bit flexible for alignment? Sheesh. And it's just one of several asinine engineering foul-ups on this engine; don't get me started on the coolant line under the lower intake manifold or the valve-train clatter in these engines!

I'll do the recalibration and run the tests you advised if the problem occurs again, everything is working fine right now, no re-occurrence in 6 days now.

Thanks for the assistance and patience @Nuke !
That coolant line is supposedly a frequent leaker, although I never had that problem in mine. The rocker assemblies are another known headache and I did have my bouts with those. The individual rockers on the arms, usually always on the exhaust side, will slowly butt up against their neighbor on the arm and begin eating away at the aluminum. Over time they can become severely misaligned and pit/gall the camshaft lobe.

Replacing the whole assembly on that head is the only real solution, but you have to go with new parts since used ones are likely suffering from same fate, and the new ones are $250 each...or they were a few years ago, probably more now that they’re getting fewer and fewer available.

If one side or the other is clattering more loudly than it has been, that could be a good indication one or more rockers on that assembly are chewing each other up. Pop that valve cover off and give them a peep. A visual inspection will usually confirm or deny the culprit. Wiggling laterally along the shaft can also identify problem rockers, as they should not have much play from side to side.

Ive got some videos on YouTube that show what I’m talking about with this. I recorded a vid of one of the ones I pulled off mine to replace. It’s pretty bad, one rocker had chewed up about an eighth of inch of its neighbor’s aluminum body. They also show the relevant pages from the service manual for removal procedure and torque specs if you need them.

But I’ll light an incense and say a prayer you don’t 🙏
 

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Discussion Starter · #16 ·
That coolant line is supposedly a frequent leaker, although I never had that problem in mine. The rocker assemblies are another known headache and I did have my bouts with those. The individual rockers on the arms, usually always on the exhaust side, will slowly butt up against their neighbor on the arm and begin eating away at the aluminum. Over time they can become severely misaligned and pit/gall the camshaft lobe.

Replacing the whole assembly on that head is the only real solution, but you have to go with new parts since used ones are likely suffering from same fate, and the new ones are $250 each...or they were a few years ago, probably more now that they’re getting fewer and fewer available.

If one side or the other is clattering more loudly than it has been, that could be a good indication one or more rockers on that assembly are chewing each other up. Pop that valve cover off and give them a peep. A visual inspection will usually confirm or deny the culprit. Wiggling laterally along the shaft can also identify problem rockers, as they should not have much play from side to side.

Ive got some videos on YouTube that show what I’m talking about with this. I recorded a vid of one of the ones I pulled off mine to replace. It’s pretty bad, one rocker had chewed up about an eighth of inch of its neighbor’s aluminum body. They also show the relevant pages from the service manual for removal procedure and torque specs if you need them.

But I’ll light an incense and say a prayer you don’t 🙏
My original coolant tube was corroded badly so I installed a new one when the engine was replaced; the first coolant tube I installed in the engine during the replacement was an aftermarket (Dorman) and was bent improperly and I had to tear down and replace it. I spent the $105 dollars for an OEM replacement tube and all is well now with that.

Sadly, I had to replace BOTH rocker assemblies with only slightly more than 1000 miles on the new engine, both shafts were galled and several of the little hydraulic units on the end of the rocker arms were bad. $650 for the pair is the going rate these days. This car has been an ordeal but I do like it enough to dig in and do the work.
Incense and prayers are appreciated!!
 

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The Bacon Hauler (‘12 Cop Charger)
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My original coolant tube was corroded badly so I installed a new one when the engine was replaced; the first coolant tube I installed in the engine during the replacement was an aftermarket (Dorman) and was bent improperly and I had to tear down and replace it. I spent the $105 dollars for an OEM replacement tube and all is well now with that.

Sadly, I had to replace BOTH rocker assemblies with only slightly more than 1000 miles on the new engine, both shafts were galled and several of the little hydraulic units on the end of the rocker arms were bad. $650 for the pair is the going rate these days. This car has been an ordeal but I do like it enough to dig in and do the work.
Incense and prayers are appreciated!!
Damn, you and that car are like old war buddies, y'all have been through hell together!

Although, I see no mention of doing the timing belt maintenance...have you waded into that quagmire yet?
 

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Discussion Starter · #18 ·
No, other than installing one on the new engine. I'm afraid that my next issue is going to be dealing with the transmission; it hasn't failed but it is starting to feel funky on the 1-2 shift occasionally.
 

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No, other than installing one on the new engine. I'm afraid that my next issue is going to be dealing with the transmission; it hasn't failed but it is starting to feel funky on the 1-2 shift occasionally.
4 speed or 5 speed auto?

If 5 speed, it’s the venerable NAG1. Change the fluid out a couple quarts at a time by extracting it out of the dipstick tube with a fluid transfer pump ([email protected]). Do that until the fluid coming out is mostly the same color as what you’re pouring in, and you’re good to go. It’ll take more fluid than doing it via pan drop, but it is easier and cleaner, and the gradual introduction of the new fluid into the system can keep older transmissions from going into shock and taking a dump like some do with all new fluid all at once.
 

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Discussion Starter · #20 ·
5 speed. I'll give that a try; I was floored when I found out that there was no dipstick. I mean seriously? No way to check the level except drain and re-fill, what genius engineer came up with that? He must live in a place that has legalized marijuana...
 
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