Toyota Aqua Vibration Issues When Switching from EV Mode to Engine

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Toyota Aqua Vibration Issues When Switching from EV Mode to Engine

Hello,

I’m reaching out for some assistance regarding my car.

I own a 2012 model with 81,000 kilometers on the odometer, which was imported by a friend. The car runs well and is enjoyable to drive, but about three months ago, I started experiencing an issue. After taking a corner, I noticed vibrations coming from the left side of the car, similar to the sensation of driving over cat eyes.

Concerned, I took it to a local mechanic. We drove the car together and discovered that the vibrations occurred when shifting from EV mode to the engine. The mechanic diagnosed it as an engine misfire. He cleaned the throttle body, spark plugs, and air filter, which improved the vibrations slightly. I then drove the car from Lahore to Islamabad using high-octane fuel. Upon arriving in Islamabad, I visited another mechanic the next day, who rotated the tires. This reduced the vibrations significantly, and after balancing, they were almost gone. I didn’t notice any issues for about a week.

However, a day before Eid, it rained heavily in Islamabad, causing road flooding. I tried to avoid the water as much as possible, but eventually had to drive through a patch that was about 8 inches deep and 200 meters long. Once I emerged from the puddle, the vibrations returned, and this time they persisted even on straight roads. As soon as the engine turned on, the car began vibrating violently, and the engine check light illuminated. The vibrations only occur when shifting from EV to engine but fade after about 15 seconds. This worried me, and since most mechanics were closed, I took the car to a local technician. He confirmed it was likely an engine misfire and suggested that the orange cable connecting the battery to the traction motor might have gotten wet. He assured me it would resolve itself, but I was skeptical since those cables are supposed to be waterproof.

I’ve been driving the car for three days now, and while the vibrations have decreased, they still appear after making turns, possibly due to the steering pump engagement. However, I’m puzzled that the engine light remains on. Today, I need to travel to Lahore, and I’m uncertain if I’ll be able to find a reliable hybrid mechanic there.

I would greatly appreciate any urgent help o r advice.

Best regards,
Lubaba

Lubaba asked on 24 Jan 2025 12:44:24 pm

1 Answer

31 views |

Car Mechanic Expert - on 24 Jan 2025 12:48:55 pm

Hello!

It seems that your car is experiencing some intermittent vibrations and engine misfire issues, likely linked to the transition from EV mode to the engine. The fact that the vibrations initially improved after cleaning the throttle body, spark plugs, and air filter, but then returned after driving through a flooded area, suggests that water exposure might be affecting critical components.

Its possible that the water could have affected the connections o r sensors related to the hybrid system, such as the traction motor cable o r other electrical connections. While these cables are designed to be waterproof, water damage can sometimes cause temporary issues if the seals are compromised o r if moisture gets into sensitive areas like electrical connectors o r the ignition system. The vibrations could also be due to other components, such as the steering pump, as you mentioned, which may engage differently when the water exposure affects its functionality.

Since the vibrations have decreased but the engine light is still on, its important to have the trouble codes read using a diagnostic tool to pinpoint the exact cause of the engine misfire. If it is related to the electrical components, it could take some time for them to dry out completely and function properly again. However, the persistent engine light indicates that the issue is still present, and driving without addressing it could lead to further damage o r poor performance.

Given that youre traveling to Lahore, I would recommend finding a reputable hybrid mechanic who has experience with Toyota Aqua o r similar hybrid systems. They will be able to perform a more thorough diagnostic check and identify any potential issues related to the hybrid system, such as the traction motor connections, engine misfire, o r other sensors.

In the meantime, it may be worth carefully checking the engine bay and any exposed electrical components to see if moisture is still present o r if there’s any visible damage. If possible, let the car sit for a day o r two in a dry area to allow any residual moisture to evaporate.

It’s good to stay cautious, and I hope you find a solution soon to avoid any long-term damage.