I hope the collective knowledge of the professional and amateur vehicle mechanics on this board can help. I’m having issues with my Hellcat that I can barely even describe. The biggest issue is that it doesn’t happen all of the time, and there is nothing stored in the computer to indicate a problem. I’ve already had an authorized Dodge mechanic check out the car, but he couldn’t reproduce the problem so he said there’s nothing he could do. We even took it on a test drive together, but it ran perfectly during the test drive. So I said I’d come back with videos. That was a couple months ago, and I’ve managed to capture the problem on video a couple times. I haven’t been back to the mechanic yet. Before I go back there and make a fool of myself again, bringing in a “perfectly fine” car, I’d like to try to get some more knowledge of the problem I’m experiencing. I have no idea what is causing it, or how to even speak about it intelligently to a mechanic. Please help.
The car is a completely stock 2018 Charger Hellcat with about 8000 miles. Fuel is 98 RON, E5 Super Premium.
Sometimes when I’m driving (doesn’t matter at what speed or type of driving), the engine will gradually start to get louder and rougher. There is a perceived drop in horsepower and the car vibrates. As I slow down, the vibration can be as violent as a blown tire–it shakes hard! Once the car comes to a complete stop, it seems to reset itself and starts working normally again. During one instance, a bunch of warning and service lights started flashing on the dashboard.
Below are links to two videos which I think best demonstrate the problem. I welcome any ideas about what might be the problem and how I might go about fixing it.
https://www.youtube.com/watch?v=Tj-6Ja0VMZI
I apologize for the poor video quality. I literally just grab my phone and start filming whenever the issue pops up.
And after that there were still no codes to be read? That in itself sounds really strange. A bunch or warning lights and no record in the onboard computer that they were turned on, never mind why?
I don’t have a reader. I haven’t been able to take it to the mechanic since the time all the lights came on and left.
The car has its own code reader in the menu where I can search for faults. That one turns up nothing, but I’m not sure if its looking for just current faults or searching for any that have popped up and disappeared. I’m not sure if the mechanic’s external reader might turn up something or not. I’ll be taking it to him within the next couple weeks.
You mentioned that you lose power, but the RPMs don’t appear to drop (at least not significantly).
I’ll bet the torque converter is slipping or otherwise have some issue.
I have no idea if this would prove or disprove anything, but you revving the engine while in park. If you can replicate the problem, that eliminates virtually everything but the torque converter and engine (ujoints, wheels, brakes, suspension, differential (if rear wheel/4wheel), road vibration rattling something etc).
But, I’m going to go with a torque converter issue. Do some googling for torque converter sounds or see if there’s anything on the internet about TC issues with that car. At least that’s the rabbit hole I’d be going down, for the moment (and I would but I don’t have time at the moment).
ETA, check your transmission fluid. Is it full? Is it clean? Does it appear full of of ‘glitter’? Does it smell burnt?
If you think there’s a problem with the transmission fluid (like, it’s full of metal flakes), I’d get it to a mechanic sooner rather than later.
If you continue to have a problem pinning this down, you might want to invest in an OBD scanner with live data. With that you can monitor in real time some important data that may give you some direction.
For example, looking at RPMs, fuel trims, O2 data, throttle position sensor could tell you if there’s a fuel delivery issue. Misfire data would tell you, well, if it’s misfiring. There may be a data pid that’ll tell you what gear the transmission is in, that could tell you if it’s hunting/randomly shifting.
Yes, it sounds like a misfire. A quick look at the hellcat forum and there’s some different reasons people have had misfires, including bad lifters, broken rocker arms, or simple spark plug issues, but the fact that yours are sometimes accompanied by christmas lights on the dash suggests that there’s an overall power loss on the engine harness – maybe a weak ground or a bad connection.
I’m stymied by the fact that there aren’t any codes stored, though.
I played the clip for my dad who tends to be good at this. I didn’t show it to him, I just let him listen and as soon as it started making the noise he said ‘that’s a wheel bearing’.
If you can replicate at lower speeds, try turning. If it’s a wheel bearing it may get better or worse depending on which way you turn (ie if you turn left and it gets worse, the right one is shot).
You could try jacking up the front wheels and spinning them by hand. If you have a bad bearing, you may (or may not) hear rubbing, grinding, scraping when you spin the wheel.
If it is, in fact, a wheel bearing, that’s another ‘sooner than later’ thing to deal with. If it locks up, you may find yourself stuck until you can get it towed.
As for the warning lights, if it’s the wheel bearing, the car may notice the problem since I believe the speed sensor is part of that hub assembly on that car. The ECU may be picking up on the problem and throwing a code for that (and probably turning off traction control and/or airbags and ABS).
At 2:45 of the first video, you go from 50 km/hr (about 30 miles per hour for the imperial-inclined) and punch it up to a cruising speed of 180 km/hr (110 mph) and then overtake a couple of vehicles at about 215 km/hr (130 mph).
Yikes. If I were your passenger I’d have a death grip on the dashboard while making this face: !!!:eek:!!!
The feeling of power loss is a bit hard too explain. The throttle feels less responsive, like and the engine just doesn’t act right. It feels like the engine is gargling fuel instead of swallowing it, and it doesn’t want to move as fast. It feels like it’s running on 4 cylinders or something. The brakes also feel mushier, like there isn’t as much hydraulic pressure in the brakes, but that part might just be paranoia. The “mushy brakes” feeling doesn’t always present itself when the car throws these fits, so I’m not sure if I’m just imagining that or not. Maybe half the time.
Transmission fluid is normal and no burning smell. In fact, there is no noticeable smell at all from the car when it does this. No temperature rising in either transmission or engine. No smoke and no smells.
The car has the ability to monitor all of this already. In the second video, I managed to switch on those gauges before I started filming. It will show 4 at a time, and I preselected Air/Fuel Ration, Horsepower, Current Gear, and Boost Pressure as I figured those might be the most relevant to the problem. I tried to keep them all in view while filming.
I think it’s definitely electronics related. The mechanic tells me that he checked the PCM and it’s fine. I think it’s faulty.
Misfiring was my original thought, and I haven’t completely given up on that thought. In fact, when I first brought this to the mechanic, that’s what I told him it was doing–misfiring. He told me two things: (1) There are no misfire codes in the computer (2) The Hellcat computer will automatically prevent (or respond to) a misfire. So I said that the computer must be faulty. He assured me that he checked the computer and there’s nothing wrong with it. I have a feeling the final solution is going to be to have Dodge replace the entire PCM. I need to rule out other issues, though. The last time I went to the mechanic with that thought, I left feeling sheepish.
I posted on the hellcat.org forums. I’m still waiting for the first response. . .
Would a wheel bearing problem only be noticeable one every couple weeks, though? The mechanic said he checked the electronic suspension and found no issues, but never specifically mentioned wheel bearings. I’m not sure if they were checked. There is no noticeable difference while turning, though.
In the second video, I was just trying to show that the car was working fine again after I exited the autobahn and then got back on. You should be able to hear a distinct different in the sound of the engine from before and after. As far as speed, I normally don’t accelerate that quickly, or bring the engine passed 5000 rpms like that. I do normally drive that fast, though. So, while I don’t accelerate as extremely as seen in the video, but I normally drive 130-160mph on my way to and from work. In light traffic, I might do up to 190mph, but closer to 150 is normal.
if the brakes feel different then it could be losing manifold vacuum (the power brake booster uses engine vacuum.)
the electronic throttle control might be screwing up; all cars today are “Throttle by wire” where the accelerator pedal only connects to sensors. the PCM controls a motor on the throttle body that opens and closes the throttle based on the pedal position and rate of change. if the throttle control motor is doing something that is in conflict with what it’s supposed to be doing, I could see all manner of odd behavior happening.
I have a friend that has a Challenger that was doing something like this. It was super new and shouldn’t have had any real issues whatsoever.
Turns out after 2500 dollars at the dealership mice had eaten some wiring around the bottom of the engine where the transmission bell housing meets up with the transmission. The wires had the copper exposed and would occasionally short out on the engine or tranny and ground out whatever they were doing. One was the torque converter lockup solenoid wiring, the other was something that ran to the ECU and when it would momentarily short out, the dashboard of his car would light up like the Starship Enterprise (60s version) and then it would go back to normal.
My mom’s Prius used to do the same thing, it turned out it was mice eating at the semi-edible environmentally friendly wire insulation that Toyota thought would be a good idea to locate in a place that you had to take the engine out to get to. I don’t know if Chrysler is using the same type of wire insulation or not, but mice freaking LOVE it, and snakes love mice, so her brand new Prius smelled like mouse urine and had a few snakes in it about two months after she got it.
Fun times.
It would seem to me if the ECU didn’t store a OBD code in its buffer when these events happen, I would check the wiring that feeds the ECU first. Sometimes the harness can get a little loose too.
