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Discussion Starter · #1 ·
Hello everyone ! I have a 2010 Challenger RT auto with 95k miles and 55k on a new engine. Mods? CAI and oil catch can. Magnaflow mufflers. My car seems to bulk while driving at a constant speed 35 mph saying through city or residential areas. Maintaining speed at 35 car wants to jerk back and forth as you gently left off the accelerator. In the old cars i would swear it was a vacuum problem. I’ve cleaned out the oil catch can and retightened the fittings. It seems to get better but then worse. I’ve tried throttle recalibration with moderate success. I’ve cleaned the MAP sensor as well to same amount success. Better than back to annoying. I am 18k since the last tuneup and 33k since the dealer changed transmission fluid and filter. I have checked for codes with scanner and there are none. Just kinda annoying. Driving auto stick makes it better at times. Anybody else have this issue?
 

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Have you checked the intake manifold bolts for proper torque? Also you may want to check engine mounts as well. My 2013 JGC had a fish bite to it on the highway and it turns out the passenger side mount was shot.
 

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The Bacon Hauler (‘12 Cop Charger)
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Does AutoStick always make the behavior go away?

Also, if you could record a vid clip and share that it would be more helpful.
 
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Discussion Starter · #4 ·
Thanks! I will check those things.

Does AutoStick always make the behavior go away?

Also, if you could record a vid clip and share that it would be more helpful.
Autostick does 90% of the time make the jerkyness vanish. At first I thought it was purely the MDS turning on and off causing it. I will try to get video. It is more of a feel than sound. However the magnaflows let you know when the MDS activates. It almost sounds like a misfire.
 

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2021 JEEP Wrangler Unlimited Willys 4X4
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Autostick does 90% of the time make the jerkyness vanish. At first I thought it was purely the MDS turning on and off causing it. I will try to get video. It is more of a feel than sound. However the magnaflows let you know when the MDS activates. It almost sounds like a misfire.
If your tuneup only consisted of spark plug replacement, I’ll almost bet you have one or more coil packs going south.
 

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You could try swapping coils from MDS cylinders with non-MDS ones. Another way is to log cylinder misfires (if your scan tool is capable) and swap coils from cylinder with highest count to one with lower count and see if it follows.
 

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The Bacon Hauler (‘12 Cop Charger)
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Autostick does 90% of the time make the jerkyness vanish. At first I thought it was purely the MDS turning on and off causing it. I will try to get video. It is more of a feel than sound. However the magnaflows let you know when the MDS activates. It almost sounds like a misfire.
I smell a rabbit hole...

Okay, so if AutoStick has an effect, but 1 out of 10 ten times it does not, I would figure out what’s different about that one time that kept AutoStick from affecting the behavior.

At that point you will be able to recreate the “fix” at will, and from there you can zero in on how it fixes it.

Once you know the how, it should be elementary to identify what’s causing it.

Also, was there any work or service done on the car just prior to the behavior starting?
 

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The Bacon Hauler (‘12 Cop Charger)
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Does AutoStick also prevent the behavior (start out from a dead stop in AutoStick)?

You said it starts at about 35 mph, does it go away eventually? What speed?

Does it matter if the engine is warmed up completely or if it’s the first drive of the day?

If you accelerate when the vibration occurs, does the vibration get worse with RPM?
 

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2021 JEEP Wrangler Unlimited Willys 4X4
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Are you thinking torque converter shudder @Nuke ?
 

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The Bacon Hauler (‘12 Cop Charger)
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Are you thinking torque converter shudder @Nuke ?
No, I am thinking somethings up with my wiring if I lose the HVAC controls simply by unplugging the left front speaker.

Oh you mean about this thread? IDK, just trying to gather intel...
 

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2020 Dodge Challenger Hellraisin Scat Pack
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Hello everyone ! I have a 2010 Challenger RT auto with 95k miles and 55k on a new engine. Mods? CAI and oil catch can. Magnaflow mufflers. My car seems to bulk while driving at a constant speed 35 mph saying through city or residential areas. Maintaining speed at 35 car wants to jerk back and forth as you gently left off the accelerator. In the old cars i would swear it was a vacuum problem. I’ve cleaned out the oil catch can and retightened the fittings. It seems to get better but then worse. I’ve tried throttle recalibration with moderate success. I’ve cleaned the MAP sensor as well to same amount success. Better than back to annoying. I am 18k since the last tuneup and 33k since the dealer changed transmission fluid and filter. I have checked for codes with scanner and there are none. Just kinda annoying. Driving auto stick makes it better at times. Anybody else have this issue?
(Why was the engine replaced? And who replaced the engine?)

That in auto stick mode affects the behavior suggests to me the problem is with the transmission. 95K miles is not a lot of miles but automatics can go bad at any time.

Can you check the transmission fluid level? Is it ok?

Absent a CEL and one or more misfire codes I would not at this time suspect coils or plugs.

Well, check that. I had a car manifested a slight hesitation at highway cruising speed. (Manual transmission.) No problems at any other times. No CEL.

Turned out a plug wire was loose on a plug. I had the plugs changed some 1000 miles earlier at a dealer and I guess the tech left one plug wire loose. It sparked over good enough for a while but the sparking eroded the wire connector. It would no longer snap onto the plug. I stopped at a hardware store and bought a set of pliers and squeezed the plug wire connector a bit so it would snap on to the plug. At a Ford dealer I bought a new set of plug wires to have for just in case my "fix" didn't last. It lasted until I sold the car after putting another 90K miles on it. The new plug wires were in the trunk. I have never had to use them.

So check the coil wire connector to the plug. While you are there be sure every coil's connection to the wiring harness is secure, too.

When was the fuel filter changed? The air filter?
 

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Discussion Starter · #13 ·
Does AutoStick also prevent the behavior (start out from a dead stop in AutoStick)?

You said it starts at about 35 mph, does it go away eventually? What speed?

Does it matter if the engine is warmed up completely or if it’s the first drive of the day?

If you accelerate when the vibration occurs, does the vibration get worse with RPM?
Cold start or if it has been sitting for 30 minutes or so it is fine no problem. After driving it for about 10 minutes or so with it at operating temperature it will start to jerk. If you accelerate the car will bog down for a second then respond.as long as you accelerate in 5th gear it is fine.

(Why was the engine replaced? And who replaced the engine?)

That in auto stick mode affects the behavior suggests to me the problem is with the transmission. 95K miles is not a lot of miles but automatics can go bad at any time.

Can you check the transmission fluid level? Is it ok?

Absent a CEL and one or more misfire codes I would not at this time suspect coils or plugs.

Well, check that. I had a car manifested a slight hesitation at highway cruising speed. (Manual transmission.) No problems at any other times. No CEL.

Turned out a plug wire was loose on a plug. I had the plugs changed some 1000 miles earlier at a dealer and I guess the tech left one plug wire loose. It sparked over good enough for a while but the sparking eroded the wire connector. It would no longer snap onto the plug. I stopped at a hardware store and bought a set of pliers and squeezed the plug wire connector a bit so it would snap on to the plug. At a Ford dealer I bought a new set of plug wires to have for just in case my "fix" didn't last. It lasted until I sold the car after putting another 90K miles on it. The new plug wires were in the trunk. I have never had to use them.

So check the coil wire connector to the plug. While you are there be sure every coil's connection to the wiring harness is secure, too.

When was the fuel filter changed? The air filter?
The original engine was destroyed when the timing guides on the engine broke. Dodge dealership replaced the engine under warranty. Since then Dodge has changed out the guides again due to recall. This car was a victim of the timing chain issue you read about on the web.
I don’t a way to check transmission fluid. I am looking to get an after market dipstick. I will check the coil wire connector. It would make sense it bing kinda in the ignition area since it occurs when the engine is warm. I’ve had bad arching plug wires on my older cars behave like that.
The fuel filter I have not changed personally. Dealer when under warranty always did those procedures. I will check that too.
I just recently recharged the CAI filter and cleaned the MAP sensor.

Yesterday I left for work early and took it up and down the interstate as a test. The throttle was really jerky when accelerating which seemed to correlate with the MDS coming on and off.. I did notice a few harsh downshifts as well when exiting the interstate. Last night when I got home I took out the PCV valve and rattled it and put it back in and started driving again. Car was perfect no issues.

I beginning to think it is either
1. Vacuum leak somewhere
2.Adaptive learning software needs updating
3. Fuel filter
4. Bad coil/ignition system
5. Maybe low tranny fluid
I just hope it is not a torque converter issue. From what I have read those symptoms are compared to running over the lane reflectors in the center of the road. It not that type of “jerk.”
 

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2021 JEEP Wrangler Unlimited Willys 4X4
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Throttle position sensor or APPS?
 

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Cold start or if it has been sitting for 30 minutes or so it is fine no problem. After driving it for about 10 minutes or so with it at operating temperature it will start to jerk. If you accelerate the car will bog down for a second then respond.as long as you accelerate in 5th gear it is fine.
Funny you mention the jerking starts after 10 minutes. I had a problem with my challenger RT manual where I would get a fishbite at low RPMs until the engine warmed up. It wasn't until recently that I logged exhaust cam position did I find that VVT was oscillating (see very bottom plot).

Turns out VVT was kicking in too soon. Just modified the tables to match that of a 6.2/6.4 M6 and it appears to resolve my problem. I have checked other stock tunes and my 2015 RT M6 seemed to have low RPM and oil temps to enable VVT.

Anyways, I was wondering if you have any means (HP tuners, Diablo or AlfaOBD) to log your engine while you drive it? That way you can look at how the cam, throttle blade, spark or knock sensors are behaving.
 
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