Why does a car shake when idling after sitting for years?
Vehicles left sitting unused for long periods often develop heavy vibrations in gear and reverse upon startup, leaving owners stranded without knowing where to begin troubleshooting. This makes it difficult to restore an older vehicle to a drivable state without wasting money on random parts.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Checking spark plugs, fuel quality, fuel filters, and transmission mounts.
- 2Flooring the throttle instead of easing into it
- 3Searching online and considering various potential parts like spark plugs, coil packs, fuel injectors, or sensors
- 4Performing a transmission service or using an anti-slip additive
- 5Checking for vacuum leaks
- 6Using a smoke kit
- 7Replacing the radiator and topping off coolant
- 8Inspecting the exhaust leak at the flex pipe
- 9Unplugging exhaust VVT solenoid raises idle to ~1,500–1,600 RPM and prevents stalling
- 10Replaced exhaust VVT solenoid
- 11Replacing parts such as the alternator, serpentine belt, valve cover, valve cover seals, spark plugs, and ignition coils.
- 12Replacing components such as cv axles
- 13Testing voltage at coils, fusebox, and accessible solenoids or sensors
- 14Testing the TCC by tapping the brakes while accelerating hard
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“When accelerating hard (over ~50% throttle) in the 15-25 mph range, there's a noise/shake that sounds like you're running over one of those rumble strips, that are placed before stop signs & persists until I ease up on the gas.”source ↗
“My only guess at this point, is a busted engine mount, or some kind of misfire that isn't showing up in obd2.”source ↗
“Any help would he a godsend!”source ↗
“My 2014 Honda Accord Sport has been shaking on and off when the AC is on and at idle.”source ↗
“It doesn't always happen either.”source ↗
“I also notice that with the AC off and sometimes putting the car into reverse it does almost the same type of vibration.”source ↗
“What else could be causing all this?”source ↗
“From a dead stop it will sometimes not respond to throttle input at all (it doesn't bog, just doesn't do anything) for maybe a half second.”source ↗
“When cruising between 10-15mph very slight throttle inputs will make it stutter in the 1k to 1200rpm range.”source ↗
“I have no idea where to start or what to throw money at first.”source ↗
“This van's (2004 Dodge Grand Caravan 3.8) has been sitting out for 3+ years and I'm considering getting it to a comfortable state to drive. It shakes the most in reverse, a little less in drive, and little less in park, and (I think) a normal amount in neutral.”source ↗
“i started it and i got engine fault limp mode, then after 1 more start it was gone and no limp mode.”source ↗
“hey there! it’s got no codes, and everything else is stock. not sure what a flex pipe is.”source ↗
“I topped it off about 2 weeks ago. But I’m pretty sure the radiator’s leaking a bit so I’ve got a new one ready to go. Not sure if that has sum to do with it.”source ↗
“Car runs fine cold/driving but once fully warm, the idle starts hunting and it stalls at stops.”source ↗
“Wouldn’t a stuck-advanced intake phaser show up as actual cam angle not matching commanded angle? Mine stays within about 1° even while the idle is hunting. Is there a mechanical way you’d recommend verifying the phaser/timing despite the scan data?”source ↗
“So my 95’ Honda Civic has been idling like this for a while now, and I’m not sure what the issue is?! It’ll also stall sometimes on idle, making that pulsing sound + vibrating.”source ↗
Where this came up
People with this problem also raised
- 3How to tell if a front end shake is tie rods or wheel bearings
- 20Why are my brakes squeaking and shaking the floorboard?
- 34Why does my car make a loud rattle when starting the engine?
- 62How to explain an intermittent car noise to a mechanic
- 3Why does my car overheat only when idling?
- 5Why does my car lurch and shake when I accelerate at low RPMs?