Hi, so happy to have found this place. This will probably be a bit long—I’ll try to keep it short.

A few weeks back, my 2005 LS430’s alternator went out. Simple but annoying, so I went to have it replaced. Got it back, everything worked again, I was happy until I started driving it home.

Since replacing the alternator (replaced with Denso, correct to my knowledge), everything has gone to hell. It has this absolutely nuts cabin vibration. I’m sure you guys know how comfortable this car generally is, it’s like driving a couch. Not anymore. It vibrates like the engine is dragging on the road, all the time, and never gets better. It vibrates from the time it’s on until the time it’s off. I’ve also noticed a huuuuge drop in MPG, which is super fun right now! There’s also a very hard shift from second to third, strange.

Anyway, I didn’t want to take it back to the place that did the alternator, and started wondering if they knocked a hose or something else. Bit the bullet and bought another OEM alternator just in case (haven’t had time to put it in myself, but have it). Took it to a local Lexus specialist, they couldn’t find anything wrong. Said maybe the idler pulley and belt/belt tensioner, so we replaced those.

No change, car started to feel like driving it was unsafe and hurting something. Reeaallly got desperate and took it to dealership. Also found nothing wrong, but said the engine mounts are “sagging” but fine and not concerning or cracked. Hoses seemed fine to them, everything seemed fine.

Two days go by, and I barely get it home from work today. No check engine lights, nothing. The transmission feels dead, the car feels dead, it’s unsafe and undriveable.

I love and baby this car, and bought it from the original owner who did the same. I don’t understand the issue and don’t know what to do now. I feel like I’m just tossing money I don’t have at it, and nothing is helping.

I live in SoCal, and it’s hot. I’ve read that the ECU can fry and need rebuilt. Does that sound like a good idea? Anyone have any experience, or ideas? I’m totally at a loss

 

If it was all good before the new alternator then in all likelihood they disturbed or broke something. It sounds like you have a misfire, for sure. Did the dealership check for codes? Did they do a visual inspection of the work?

 

FWIW I got new alternator recently (from Firestone car care, had to be towed there, no idea of brand) and car was completely fine after, just like before. Hope you can solve it Years ago Jiffy Lube installed a bad PCR valve in my old car and it dieseled every time I turned it off until fixed...