Vibration, occasional high idle, and other shenanigans in 2009 auto Yaris hatch - Toyota Yaris Forums

firebird1999us · 12-14-2018, 10:47 AM

I just changed the spark plugs, battery, the belt, the midpipe/cat and O2 sensors to clear all the bad codes, and the alternator after the original factory alternator went bad at 346k miles. I swapped it out with a Duralast unit from autozone. The car drives fine and I don't have any issues while driving on the highway at all.

1-The high idle occurs at startup The tach runs up to about 1000, hangs there for a second, and then eventually settles back down to 600. Once it's at 600 its solid and does not fluctuate. This only happens at startup.

2-The vibration seems to be the worst when I come to a stop sign and have the heat/air running. The rpm does not change though - it stays a solid 600 when I'm at a complete stop with the shifter in drive at a light. it's like a periodic shudder in the car and I have my foot on the brake at the time. it is considerably less noticeable with the heat/air off but still happens. DOES NOT happen while I'm actually driving. If the car is parked but running with the air going full blast, or in neutral I don't believe it does this but I'll have to retest later to make sure i'm remembering correctly. I'm thinking this has something to do with either the AC, the clutch on the AC pulley or the brake system... I believe CTScott suggested the brake booster or the master cylinder in another thread?

So I should also mention I made the mistake of using a recommended mechanic at the last minute to swap the alternator... it was like 4:00p the day before thanksgiving, I limped into the autozone lot, it was a bad situation, and I didn't trust myself to change an alternator on the fly in the parking lot and I definitely wasn't making it another 50 miles home on the bad alternator. So the mechanic I used put it in and for whatever reason removed the motor mount to do so. When he put it back in he cross threaded one of the bolts going into the top that attaches to the bracket that's bolted to the engine. He then drilled out that hole and used a large head bolt of some sort with a locking nut on the bottom all the way through instead of a bolt that threads into the mount - it bolts from the bottom. The second shop I took it to locally told me the mount looked and felt totally solid...

The other part of that story is that the guy got so focused on the motor mount that he forgot to tighten the bolt on the bottom of the alternator. The car drove fine until the next day when I got a horrendous belt squeal. I went to tension the belt and saw it was basically hanging on the tensioner bolt and the pivot bolt on the bottom had backed out or was never tightened. Once I tightened it and tensioned the belt I've maybe had one or two small chirps on really cold starts.

I've driven the car probably 1500 miles since this whole ordeal started and the vibration and high rev are the only issues I've had. prior to me noticing this vibration/high rev thing - current mechanic said mechanically the car looked solid and he could not find any compression issues with the engine.

12-14-2018, 10:47 AM	#1
firebird1999us Drives: 2003 Mach 1 Join Date: Oct 2008 Location: Georgia Posts: 293	Vibration, occasional high idle, and other shenanigans in 2009 auto Yaris hatch I just changed the spark plugs, battery, the belt, the midpipe/cat and O2 sensors to clear all the bad codes, and the alternator after the original factory alternator went bad at 346k miles. I swapped it out with a Duralast unit from autozone. The car drives fine and I don't have any issues while driving on the highway at all. 1-The high idle occurs at startup The tach runs up to about 1000, hangs there for a second, and then eventually settles back down to 600. Once it's at 600 its solid and does not fluctuate. This only happens at startup. 2-The vibration seems to be the worst when I come to a stop sign and have the heat/air running. The rpm does not change though - it stays a solid 600 when I'm at a complete stop with the shifter in drive at a light. it's like a periodic shudder in the car and I have my foot on the brake at the time. it is considerably less noticeable with the heat/air off but still happens. DOES NOT happen while I'm actually driving. If the car is parked but running with the air going full blast, or in neutral I don't believe it does this but I'll have to retest later to make sure i'm remembering correctly. I'm thinking this has something to do with either the AC, the clutch on the AC pulley or the brake system... I believe CTScott suggested the brake booster or the master cylinder in another thread? So I should also mention I made the mistake of using a recommended mechanic at the last minute to swap the alternator... it was like 4:00p the day before thanksgiving, I limped into the autozone lot, it was a bad situation, and I didn't trust myself to change an alternator on the fly in the parking lot and I definitely wasn't making it another 50 miles home on the bad alternator. So the mechanic I used put it in and for whatever reason removed the motor mount to do so. When he put it back in he cross threaded one of the bolts going into the top that attaches to the bracket that's bolted to the engine. He then drilled out that hole and used a large head bolt of some sort with a locking nut on the bottom all the way through instead of a bolt that threads into the mount - it bolts from the bottom. The second shop I took it to locally told me the mount looked and felt totally solid... The other part of that story is that the guy got so focused on the motor mount that he forgot to tighten the bolt on the bottom of the alternator. The car drove fine until the next day when I got a horrendous belt squeal. I went to tension the belt and saw it was basically hanging on the tensioner bolt and the pivot bolt on the bottom had backed out or was never tightened. Once I tightened it and tensioned the belt I've maybe had one or two small chirps on really cold starts. I've driven the car probably 1500 miles since this whole ordeal started and the vibration and high rev are the only issues I've had. prior to me noticing this vibration/high rev thing - current mechanic said mechanically the car looked solid and he could not find any compression issues with the engine.