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Hey folks! I have a 2005 300C (5.7 Hemi) with about 200 000km. Lately, it seems the RPM is uneven when I hold the car at certain speeds. Like, let's say I try to hold the speed at about 50kph, the rpm seems to oscillate, gaining or losing about 50-100rpms repetedly, which kind of makes it feel like the car wobbles a little.

Also, moderate accelerations lead to sometimes stuttering, or the car apparently shifting too early and slowing my acceleration to a crawl unless I give her more gas... though due to the stuttering bit, I blame the spark plugs which are already due, according to a mechanic's inspection.

Thoughts?
 

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Did you figure this issue out? The reason I ask is my car was doing almost the exact same thing, rpms oscillating at cruising speeds, transmission not shifting down easily, making a vibrating noise sometimes also. I took it to the dealership and they did 3 different transmission software updates. Got it back yesterday and the issue is gone.i would recommend checking for the software updates for your transmission
 

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Did you figure this issue out? The reason I ask is my car was doing almost the exact same thing, rpms oscillating at cruising speeds, transmission not shifting down easily, making a vibrating noise sometimes also. I took it to the dealership and they did 3 different transmission software updates. Got it back yesterday and the issue is gone.i would recommend checking for the software updates for your transmission
Alright. I'll try to go to a dealership for that. Is your 300 a 2005 aswell?

Also, my EGR Valve needs to be replaced and the guy at the garage said maybe it's the valve not working as smoothly as before, thus causing the wobbles. And the shifting thing, well I still think it has to do with spark plugs, maybe it's just misfires... But that would make for some very very well timed misfires so..

How much did it cost you to get the transmission software updates?
 

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Did you figure this issue out? The reason I ask is my car was doing almost the exact same thing, rpms oscillating at cruising speeds, transmission not shifting down easily, making a vibrating noise sometimes also. I took it to the dealership and they did 3 different transmission software updates. Got it back yesterday and the issue is gone.i would recommend checking for the software updates for your transmission
Hello Erict300s,
We are happy to hear your dealer was able to assist with your recent concern. Please do not hesitate reaching out to us in the future if you have any questions or concerns. We're always happy to assist.
Laura
ChryslerCares
 

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Consistent misfires should be throwing engines codes... Do you have these? My 300S is a 2014. Egr valve.... Idk... I have an oil catch can installed so unsure if your issue could be related to that it's hard to say. Swap out spark plugs and go from there, that's easy enough and not very expensive. The dealership charged me 402 dollars for the updates which I think is BS since the car only has 51k miles on it but thats Chrysler for ya🙄
 

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Consistent misfires should be throwing engines codes... Do you have these? My 300S is a 2014. Egr valve.... Idk... I have an oil catch can installed so unsure if your issue could be related to that it's hard to say. Swap out spark plugs and go from there, that's easy enough and not very expensive. The dealership charged me 402 dollars for the updates which I think is BS since the car only has 51k miles on it but thats Chrysler for ya🙄
402$ ? Yiiiikes. I'm definitely going to research this more and wait until I fixed my spark plugs and EGR valve before going there. I presume it'd be even more expansive for me, because canadian dollars and whatnot. Thanks alot man! I'll still have a talk with Chrysler about these software updates in case it's also valid for the 2005 model.
 

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Worth a shot. Unfortunately for me the transmission updates didn't work. Issue came back and it looks as if I'll be doing a transmission replacement😞 never buying a chrysler/jeep/ dodge product again
 

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Worth a shot. Unfortunately for me the transmission updates didn't work. Issue came back and it looks as if I'll be doing a transmission replacement😞 never buying a chrysler/jeep/ dodge product again
Damn, sorry to hear that :( Maybe hit up a local mechanic, see if they know stuff? Or go back to Chrysler and tell them their updates didn't change a thing and that perhaps you should recover some of that 400$. (Not that I expect any refund to work but... Who knows :V )
 

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Lol Thanks for the sympathy, tried going back but they don't care. Recommended I change the Transmission. The joys of owning a chrysler 🤦‍♂️
 

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Lol nice. I have had nothing but bad luck with mine. 2014 300s 5.7L, bought it with 27k miles on it. Motor the a rod right through the block at 46k miles and Chrysler wouldn't cover it because the warranty expired by 2 months even though milage was under. Changed the motor myself for approx 5000$ and now trans issues at 52k miles😂 sorry to hijack your post. Good luck with it, could always be worse😊😊
 

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Alright. I'll try to go to a dealership for that. Is your 300 a 2005 aswell?

Also, my EGR Valve needs to be replaced and the guy at the garage said maybe it's the valve not working as smoothly as before, thus causing the wobbles. And the shifting thing, well I still think it has to do with spark plugs, maybe it's just misfires... But that would make for some very very well timed misfires so..

How much did it cost you to get the transmission software updates?
A couple things. First, most lame dealers and many independents are too lazy to troubleshoot almost any problem anymore, and there solution is to change the part. It happened to me. Worked fine one day and the next day the transmission would go into limp mode. After doing the normal stuff....reset the code, check the fluid level and condition (I knew it was fine though) the code kept coming back. Had it towed to a shop and they did exactly what I did and told me it needed a new transmission for $3500. I had it towed back home and did a little more troubleshooting. Turned out to be a bad Transmission Control Module. Cost to fix...$200. If I had let those clowns change the transmission, it still wouldn't have worked and it probably would have ended up costing me who knows how much more, not to mention all the BS excuses they'd have given as to what was wrong.

Second, you do know that your 5.7 has the Multi-Displacement System (MDS) which cuts off 4 cylinders at cruise and when all other parameters are met?? When it goes in and out of MDS there is an RPM shift of about 200 RPM or so, but your speed shouldn't change. If you have a stock exhaust system and a stock tune, you may not even notice when it goes in and out of MDS. If you have a custom (louder) exhaust and/or a tune, you either hear it or feel it transition.

Third, your mechanic was right. If an EGR Valve is not working correctly, you'll get symptoms like rough/stalling idle, engine RPM surging or bucking, reduced fuel economy and performance. What sometimes happens is one of these two things. The Valve takes on a mind of it's own and rapidly changes setting (sometimes to unrealistic %ages) and the PCM responds by trying to correct it. This is the cause of RPM surging/hunting. If you can monitor "Commanded" vs. "Error Correction" of the EGR Valve, you can see this occurring in real time. The other thing that sometimes happens is the pintle in the valve gets stuck (usually carbon caused) in some intermediate position and you'll get mostly poor idle quality and poor fuel economy and performance.

If the problem is the EGR Valve, the part is less than $50 (to my knowledge all made in China) and a fairly easy do it yourself home fix.....if you have the tools and mechanical ability. A shop should only charge you about an hour or two (at most) for labor to change it for you.

Happy hunting and hope you find the problem and get it fixed at a reasonable cost.
 

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A couple things. First, most lame dealers and many independents are too lazy to troubleshoot almost any problem anymore, and there solution is to change the part. It happened to me. Worked fine one day and the next day the transmission would go into limp mode. After doing the normal stuff....reset the code, check the fluid level and condition (I knew it was fine though) the code kept coming back. Had it towed to a shop and they did exactly what I did and told me it needed a new transmission for $3500. I had it towed back home and did a little more troubleshooting. Turned out to be a bad Transmission Control Module. Cost to fix...$200. If I had let those clowns change the transmission, it still wouldn't have worked and it probably would have ended up costing me who knows how much more, not to mention all the BS excuses they'd have given as to what was wrong.

Second, you do know that your 5.7 has the Multi-Displacement System (MDS) which cuts off 4 cylinders at cruise and when all other parameters are met?? When it goes in and out of MDS there is an RPM shift of about 200 RPM or so, but your speed shouldn't change. If you have a stock exhaust system and a stock tune, you may not even notice when it goes in and out of MDS. If you have a custom (louder) exhaust and/or a tune, you either hear it or feel it transition.

Third, your mechanic was right. If an EGR Valve is not working correctly, you'll get symptoms like rough/stalling idle, engine RPM surging or bucking, reduced fuel economy and performance. What sometimes happens is one of these two things. The Valve takes on a mind of it's own and rapidly changes setting (sometimes to unrealistic %ages) and the PCM responds by trying to correct it. This is the cause of RPM surging/hunting. If you can monitor "Commanded" vs. "Error Correction" of the EGR Valve, you can see this occurring in real time. The other thing that sometimes happens is the pintle in the valve gets stuck (usually carbon caused) in some intermediate position and you'll get mostly poor idle quality and poor fuel economy and performance.

If the problem is the EGR Valve, the part is less than $50 (to my knowledge all made in China) and a fairly easy do it yourself home fix.....if you have the tools and mechanical ability. A shop should only charge you about an hour or two (at most) for labor to change it for you.

Happy hunting and hope you find the problem and get it fixed at a reasonable cost.
Wow, thanks alot for that! I was wondering why my rpm seemed to drop at cruise, despite having only 4 gears. Also thanks to your post, if my car still does funky things after I change the egr valve and whatnot (I have the parts, I'm just waiting for my brother to come over with the tools haha), I'll check out the TCM! How would you troubleshoot it though?
 

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I'd do one thing at a time and see if that cures the problem. If you transmission only has 4 forward gears, you do have a problem, because it is a 5 speed transmission....4 plus one overdrive gear. The ideal sequence of events should have been to check (with a quality computerized diagnostic scanner) all engine/fuel management modules first and find out for sure what is really going on. Since you already have the valve, try that first then, if that doesn't work we'll try something else....like put a good diagnostic scanner on it. TCM's don't normally fail that often so, unless you only have 4 forward gears, we won't worry about that right now.
 

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I can only select 1 through 4 manually (by tilting the gear selector(?) left and right when it's in D) and then if I push it towards "+" once more, when already in 4th, it'll just go back to "D" (in the gauge cluster) and drop rpm (when on the highway, for example). Which I presume is the overdrive gear.

I also feel like this paragraph is messy as hell but I hope you understand what I'm trying to say.
 

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I get it. The way yours works is the way the completed stock TCM is set up. You still have 5 forward speeds.....check them when you're driving. It may be a little problem (watch the RPM drops on the upshifts) because of the squishy shifts. The "D" is the 5th (overdrive) gear. To make the "5" show up you'll need to purchase some sort of handheld tuner (probably one of the Diablosport ones would work best for you) which will allow you to change it over to a true "autostick" transmission where it won't upshift until you move the lever and will stay in the gear you have selected until you come to a stop. You can also use it as it is now....just select "Drive". You will also be able to do 2nd gear starts with it, which can be handy if you live in the snow belt. The shifts will also be quite a bit firmer, especially at wide open throttle. It will also allow you to install one of several "pre-canned" performance tunes for the engine which will up your horsepower as much as 20-30 hp.....noticeable.
 

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Yes I am aware of the MDS sensors and the inherent tone change when it kicks on and off the 4 cylinders. When I replaced the motor I replaced the MDS sensors but one of them must have been bad from the start and I kept getting an error code for cylinder bank deactivation so I used the predator tuner to eliminate the MDS altogether. Works perfectly. However before the motor blew I was having issues with rpms going up and down constantly at cruising speed, also on acceleration car would surge sporadically. One day it gave me a code for incorrect gear ratio and the associated limp mode. Cleared code, did a filter/fluid change on transmission and issue went away for months. Recently issue returned and seems to have progressively gotten worse. Making a vibrating noise under the car, acts like it wants to shift down but doesn't, rpms wobbly again, I can drive the car in manual mode and it seems better but definitely not perfect. Dealership says it could be "valve body" in the transmission? Or transmission itself... Recommended I change transmission myself. And with no error codes I have nothing to go by. I'm at a loss
 

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What happened to the engine? The newer Hemi's are "suppose" to be better than the earlier ones. The only things I have heard as being potential problem areas are all valve train related......cam phaser, and timing chain and tensioner. Rotating assembly problems are extremely rare and, again, sometimes caused by the use of the wrong oil or never changing it as needed.

Be real cautious before jumping into a new transmission. So many stealers and independents are lazy and won't do any real troubleshooting.....just say it needs a new transmission. Do you have a good quality scanner that will read the transmission? Most lower end units won't and, at most, it'll give you a P0700 code which means there is some sort of problem with the tranny.

Has the transmission ever been serviced? Has the fluid level been checked as per FSM instructions? If you don't have a good quality scanner, I recommend you pick one up. It'll save you lots of $$$ in the future, as all newer vehicles need this for more accurate troubleshooting. One of the more common problems with the NAG1 transmission is the conductor plate on the valve body. It can give you all kinds of strange symptoms. Rarely does the TCM fail.

Who rebuilt your engine? It's extremely uncommon to have an MDS Solenoid fail. At most they'll get gummed up due to lack of (or no) maintenance ever being done. They also work better with a good synthetic oil (I use Redline), as do the MDS Valve Lifters. Only problem I've ever heard of with MDS lifters is the engage/disengage pin fails and/or jams.
 

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Motor failed at 46k miles, blew a connecting rod through both sides of the motor. I get maintenance done every 3k miles so it wasn't because of that. No idea why it happened. I bought a motor from Frasiers with upgraded internals and replaced myself(0 miles). It did not come with mds solenoids and the ones in the original would not come out without breaking, so I bought all new and replaced. I assumed one must be bad (or possibly bad electrical connector) because I started getting the cylinder deactivation warning light, and simply used Predator tuner to deactivate. The transmission is another animal altogether. I'm leaning toward taking it to a transmission shop and see what they tell me because the dealership has been next to zero help. Yes I had the transmission serviced with a filter/fluid change. Seemed to eliminate the issue for a short period of time but now the issue is back with a vengeance. Dealership says it could be valve body or trans itself. But with no codes to read they have no clue
 
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