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Strong Vibration at Low Speeds when in 5th Gear
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sam314159
New User
Feb 20, 2012, 9:29 AM
Post #1 of 7
(5593 views)
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Strong Vibration at Low Speeds when in 5th Gear
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I’m hoping to get a couple of troubleshooting ideas from you guys; this issue has eluded my mechanic and most of my car enthusiast friends.
Vehicle Information - 2002 Mitsubishi Montero Limited Edition
Problem Symptoms
- Strong vibration that feels like it’s shaking entire car.
- Vibration only occurs when in 5th gear and RPM around 1800-2000.
- 5th gear is very smooth when above 2200 RPM.
- Wasn’t able to reproduce problem in any other gear or in neutral.
- Once car starts shaking I have two options to immediately stop it, give gas to exceed 2000 RPM or take foot off gas, if I stay at the RPM “sweet spot”, the car will keep shaking.
Troubleshooting
- Mechanic suspected U-joint issue but he thinks the joints are OK.
- Mechanic changed transmission fluid and filter; he said the magnet at the bottom of the pan looked OK.
- Mechanic said to give the new fluid a few days and see if it helps. It’s been 3 days since I changed the fluid; I drove about 80 miles on new fluid. The vibration is still happening.
Any ideas on what else could be causing this?
Thanks in advance for the help guys. I love this car and I hate to think that it may be time to replace it.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 20, 2012, 11:36 AM
Post #2 of 7
(5544 views)
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Re: Strong Vibration at Low Speeds when in 5th Gear
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Question on this is how fast are you going at 1,800 in lock up mode no doubt for 5th gear? It may be lugging the engine? Most vehicles give you a choice to disable lock up or in this case 5th gear which I'll call overdrive.
Is this something new? You might consider a higher end code reading for some ideas that haven't put on a warning light yet,
T
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sam314159
New User
Feb 20, 2012, 12:15 PM
Post #3 of 7
(5533 views)
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Re: Strong Vibration at Low Speeds when in 5th Gear
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This only happens when I'm cruising at about 30-40 mph and barely giving it gas to maintain speed. It's most noticable when I've been going 80 mph on the highway and then I take an exit and slow down to 30-40 mph, seems like the car is staying in 5th gear, which I thought it was supposed to, right?
This is a new problem, it only started two weeks ago or so. Someone else guessed that it felt like an engine lugging, but I'm not sure why the problem would start now.
Thanks for the reply Tom.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 20, 2012, 12:38 PM
Post #4 of 7
(5526 views)
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Re: Strong Vibration at Low Speeds when in 5th Gear
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Still guessing at this. This could be the engine plain needs some diagnostics for lower RPM faults. It should kick out of so called 5th gear at those low speeds which is straining now a high mile vehicle so shows up more?
I'm really not sure but since this can kick out of it I think it's getting some poor fuel or spark delivery making it feel awful. My own vehicles hate OD they are called at those speeds trying to guess at what gear to be in for hills or whatever and there's nothing wrong with them but since this is new or recent there should be something to fix.
Things as basic as vacuum leaks could be delivering credible but wrong info or a list of maybes. I suggest some seriously qualified help to know if it's that or trans has an issue.
Only so much the web can do with something like this if no codes are really waiting
T
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 22, 2012, 8:30 AM
Post #6 of 7
(5475 views)
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Re: Strong Vibration at Low Speeds when in 5th Gear
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Dang - You used to be able to adjust shift timing via a plain cable sensing throttle position and a vacuum modulator that is sensing load on engine but would bet big time this is all electronic impulses sent to do the same things via computer controls.
You may need to consult a transmission specialist to see if there's any resetting of that in this one now. I actually doubt it but can't say for sure.
If there is high manifold vacuum it will convert that to say there's little load on it and go ahead and up shift. When you floor it, or a load such as even going up a hill the manifold vacuum drops and it should pick the next lower gear (if within range via RPMs) so for some reason it may be getting a signal of high manifold vacuum for some unknown reason?
I would think if this is NOT running properly and can vibrate/stumble a code is waiting but not strong enough yet to be a hard code.
Need to let a real trans tech witness this and suggest what might be adjustable as I'm pretty sure this isn't good for it,
T
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 22, 2012, 8:31 AM
Post #7 of 7
(5472 views)
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Re: Strong Vibration at Low Speeds when in 5th Gear
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I would suspect a problem with the torque converter. You need to get it to a trans shop for diagnosis.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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