Very Odd RPM's
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Joined: Nov 2010
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From: Ottawa, Ontario
Mercedes C230 2005
Very Odd RPM's
So i've been looking for a while about this problem. I've noticed a really strange RPM problem while driving. The problem doesn't really occur if in P or in D stopped.
Let's say i'm going 110 KM/H on the highway while having cruise control engaged, the rpm's act strangely going up and down. If i am at 3000 RPM we'll say, the needed would move ever so slightly but enough for me to notice. No big up's or down's, just moves like if you were waving your index finger up and down slowly...
I'm on cruise and would normally understanding hills and what not, but this just seems like it's all the time. When i start it it's not there for the first 5 min. , but after of course it comes back and almost feels sluggish when accelrating.
This of course is very annoying and I will be chaging the plugs and cleaning the TB this weekend hopefully to clear upa nything. No codes nothing. Mornings have a little rough start, but that's another page to start which i've gotten alot of information in regards to alternator/pulley's
Any help would be greatly appreciated. I turned on the car let it sit and notice the voltage is at 13.5
Dereck
Let's say i'm going 110 KM/H on the highway while having cruise control engaged, the rpm's act strangely going up and down. If i am at 3000 RPM we'll say, the needed would move ever so slightly but enough for me to notice. No big up's or down's, just moves like if you were waving your index finger up and down slowly...
I'm on cruise and would normally understanding hills and what not, but this just seems like it's all the time. When i start it it's not there for the first 5 min. , but after of course it comes back and almost feels sluggish when accelrating.
This of course is very annoying and I will be chaging the plugs and cleaning the TB this weekend hopefully to clear upa nything. No codes nothing. Mornings have a little rough start, but that's another page to start which i've gotten alot of information in regards to alternator/pulley's
Any help would be greatly appreciated. I turned on the car let it sit and notice the voltage is at 13.5
Dereck
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2019 G70 6MT & 2022 Ford Maverick XL
The alternator is charging correctly. 13.5 at idle is OK. Should be 14.1-14.2 in motion. Slight RPM variations are nothing to be concerned with. Myself and Phil (nlpamg) both have a slightly rough start up on cold mornings and we've both pretty much just lived with it for a while. My car's been doing it since last year. I'm not sure what causes it but Phil has done pretty extensive work to his 05 and it still does it. Our cars are both over 100k miles at this point, mine having the most at just shy of 119k. Aside from the slightly rough first start the car runs fine.
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Joined: Nov 2010
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From: Ottawa, Ontario
Mercedes C230 2005
About to hit 122K so i know I should be changing perhaps Fuel Filter, seems like my gas mileage sucks!
But only when it's cooler it starts rough. If it's in let's say a heated garage.. no problems..
But that damn idle... nothing like i said again that jumps and would make me **** my pants lol... but still. It's annyoing and don't wanna be throwing 3k of parts at it.. One baby step at a time I guess...
But only when it's cooler it starts rough. If it's in let's say a heated garage.. no problems..
But that damn idle... nothing like i said again that jumps and would make me **** my pants lol... but still. It's annyoing and don't wanna be throwing 3k of parts at it.. One baby step at a time I guess...
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Yep, same here for the slightly rough start.. Only when it is cooler and the car sits outside. If it is garaged, normal start. If it is warm out, normal start. It's strange but I can live with it. If it causes additional problems someday I'll cross that bridge when I get there.
Film these RPM fluctuations and post a video.
Film these RPM fluctuations and post a video.
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
This is not an idle problem. If it only happens on cruise control (tempomat) it is the car's throttle maintaining speed. The TC clutches allow some slip to prevent vibration transfer & the throttle cycles slightly to maintain speed. More noticeable on 4 cyl cars.
Only worry about it if it can be felt. In which case throttle actuator or TC clutches are messing around.
EDIT - it will be more noticeable when warm & the transmission fluid thins out.
Only worry about it if it can be felt. In which case throttle actuator or TC clutches are messing around.
EDIT - it will be more noticeable when warm & the transmission fluid thins out.
Last edited by Glyn M Ruck; Sep 19, 2011 at 12:27 PM.
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From: Ottawa, Ontario
Mercedes C230 2005
Thanks guys for the quick response... Well it's as if it's a glitch with the rpm's.. At first I thought for sure it's adjusting.. Just sometimes it can seem the rpm's dip fast enough and go back up.
As stated i'm gonna clean the TB this weekend.. And pray it's not an actuator per reading phil's thread and others. Pretty quick responses.. gotta say love this site.
1st rough start int he morning.. almost stalling it seems. but catches.. then rest of the day she's fine.. I changed spark plugs myself, maybe the kid at the parts counter gave me the wrong type, but then again, i would of noticed something the first day of swapping them out ...
As stated i'm gonna clean the TB this weekend.. And pray it's not an actuator per reading phil's thread and others. Pretty quick responses.. gotta say love this site.
1st rough start int he morning.. almost stalling it seems. but catches.. then rest of the day she's fine.. I changed spark plugs myself, maybe the kid at the parts counter gave me the wrong type, but then again, i would of noticed something the first day of swapping them out ...
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Joined: Nov 2010
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From: Ottawa, Ontario
Mercedes C230 2005
This is not an idle problem. If it only happens on cruise control (tempomat) it is the car's throttle maintaining speed. The TC clutches allow some slip to prevent vibration transfer & the throttle cycles slightly to maintain speed. More noticeable on 4 cyl cars.
Only worry about it if it can be felt. In which case throttle actuator or TC clutches are messing around.
EDIT - it will be more noticeable when warm & the transmission fluid thins out.
Only worry about it if it can be felt. In which case throttle actuator or TC clutches are messing around.
EDIT - it will be more noticeable when warm & the transmission fluid thins out.
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2019 G70 6MT & 2022 Ford Maverick XL
My car has new plugs, new battery, new fuel filter, all the correct parts. The rough start remains initially after cool nights. If you do happen to find a solution please share.
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Thread Starter
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From: Ottawa, Ontario
Mercedes C230 2005
Just had the rotors and pads replace, thought i'd be good.. Of course it's starting to get colder in Ottawa, ON, and colder = crappy rough start.
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Mercedes C230 2005
I seen you all over those posts today in alot of diff. posts.
Did you end up changing your alternator?
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
It will have the fluctuating idle if driving without cruise control.. Just seem more noticeable on cruise as i'm not pressing gas.. which could be the way i drove at first.. but no... almost seems like maybe old fuel filter or what your saying with TC clutches? Tranny?
The minute you touch the throttle pedal to accelerate you are no longer at idle. You say in your original post that "The problem doesn't really occur if in P or in D stopped." That is at idle.
What you describe is that the RPM surge up and down at higher RPM than idle with constant throttle opening. Yes??? This is not idle.
Clean the throttle body & look for wear & an air leak at the throttle plate shaft in the TB.
Good luck.
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From: Ottawa, Ontario
Mercedes C230 2005
Yeah thanks for the help though man, I really appreciate it 
I'm not as mechanically inclined as I'd like to be, but I try.
I'll be doing that this weekend and re-post and see how it goes. Someone was saying to directly spray the TB cleaner inside... After reading some posts, it seems the best is scott towel or something like that and get well around it.
I did the throttle reset, it seemed to help and for the first time in history of owning the vehicle, it gave me more gas this morning, it was just a tad higher then the previous night. This car... Glitches man
I'm not as mechanically inclined as I'd like to be, but I try.I'll be doing that this weekend and re-post and see how it goes. Someone was saying to directly spray the TB cleaner inside... After reading some posts, it seems the best is scott towel or something like that and get well around it.
I did the throttle reset, it seemed to help and for the first time in history of owning the vehicle, it gave me more gas this morning, it was just a tad higher then the previous night. This car... Glitches man
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From: Ottawa, Ontario
Mercedes C230 2005
you should take a look at rabney72 some of his posts....
This guys is very nice and took the time out of his day to call me and help me out.. again this site is the greatest
This guys is very nice and took the time out of his day to call me and help me out.. again this site is the greatest
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2019 G70 6MT & 2022 Ford Maverick XL
Yeah I saw that but my car and his car had different symptoms. Mine only has a slight stumble at first start. Nothing else. My alternator charges fine, A/C works fine, no funny noises or vibrations to speak of.
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From: Ottawa, Ontario
Mercedes C230 2005
After reading some posts with that rough start.. I'm going ahead with a temp sensor for the hell of it this weekend.
I figure maybe there is a wrong readin in the morning. I'll let you know. Also will purchase the necessary stuff for the block heater.
I figure maybe there is a wrong readin in the morning. I'll let you know. Also will purchase the necessary stuff for the block heater.
