Toyota Aqua - Problems & Solutions

[hassan4772]

Hi,
I have a Toyota Aqua, S Style Black, Model 2016, Import 2018 & Registered 2019. I will be using this thread to post my questions and look for solutions.

[haseeb.basharat]

Any information on any shop/business owner in Lahore Bilal Gunj willing for such a transaction shall also be helpful. I can pay a sensible differential amount for the swap.

You will have to go to bilal ganj yourself.
Park car at the hospital parking right next to bilal ganj. Look for the best deal you can get in bilal ganj. Only purchase once you have checked them properly by turning them on.

[hassan4772]

1. I got this car at about 75,000kms. Now it is at 150,000kms. I am currently using Toyota Petron Plus 10W30 but planning to switch to 5w30. Would it be a wise thing to do at this stage?

2. What is the transmission oil change interval for this car? I've been reading here and there that it does not require replacement? I am having a hard time accepting that.

3. I hear a rattle from underneath the car at low revs, probably from the EGR unit as I remember i got the car lifted and tapped on the rectangular unit and it rattled from inside. No check lights, no change in exhaust sound, no drop in mileage etc. What should be done here?

@Xulfiqar @syncview @capsat @Storm

[hassan4772]

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[hassan4772]

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[hassan4772]

Hi Guys, i am back with another problem in my Toyota Aqua.

While driving today, my car started showing ABS/VSC lights and the brake lost all assist power and it became very hard to brake.

I connected it to Techstream and it shows C1A50 (Brake System Malfunction) and C1391 (Abnormal Leak in Accumulator). I cleared the codes and drove the car and everything appeared to be back to normal. However, the accumulator pump now seems to run for 3-4 seconds after every 15 seconds or so.

Need guidance on what went wrong and what would be the required corrective action? Does this car (2016 Aqua/Prius C) have separate units for brake accumulator and pump or is it a single unit?

Would also appreciate if someone could guide me towards a good workshop in Lahore to get this fixed.

[hassan4772]

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[hassan4772]

@Xulfiqar @syncview @capsat @Storm please guide.

My understanding is that the main issue is the abnormal leak in the Accumulator (Part 1) and due to that abnormal leak, another Part 2 (pump?) now has to work more frequently and for longer intervals which will ultimately result in its premature failure.

What's the exact name for Part 2?

The routine practice amongst Prius users here has been of replacing both parts sourced from junkyard. What if I don't prolong the issue and only replace the Accumulator (Part 1)? Isn't the second part (pump?) still functional and should revert to its original functioning if the abnormal leak from the accumulator is handled promptly?

[Xulfiqar]

The electrohydraulic unit isn’t serviceable separately, you can try a different accumulator but thats about it, its a hit or miss.

Ive always told people to install a new toyota unit for peace of mind.

[hassan4772]

I think i was not clear enough. The trend here is to replace both the 1) Brake Booster assembly and the 2) Brake Booster Pump assembly (which comprises of the accumulator and the pump.)

I was thinking to only try replacing the #2 i.e. brake booster pump assembly to see if solves the issue.

[Xulfiqar]

You can try, there is no approved or recommended procedure to piecemeal repair any part of the EH assembly,, I was saying on personal workshop experience to not piecemeal it unless you are going to dump the car after repairs.

[hassan4772]

So i am back with a new situation and a few questions.

Frequent Non EV Running
After observing for about two weeks, i have noticed that the car's engine runs more frequently than it used to do until last year same days (it's the start of winters here). Even with the car in Park, HV battery fully charged (8 bars), warmed up coolant and no ac/heater, the car either does not switch to EV mode or if it started off in EV mode it will just switch on the engine and idle for as long as it's powered on. The HV bars keep moving between 6 and 8.

In such condition, Techstream tells me that Engine Idling has been requested under Hybrid Control and under Engine Control it shows me that the engine is operating Independently. The HV block voltages are within 0.5 Volts of each other. Changes are also uniform on stress.

The car does behave well after being parked overnight but only for a couple of short trips and then we have engine running almost all the time for the remaining, specially longer trips of the day.

Engine Shudder/Missing
The engine has a noticable missing / shudder when in low RPMs / speeds upto 30/40 km/h / when HV battery is down to 2 bars. Except for these conditions, the engine and throttle response is stable. If I engage cruise control at speeds between 50 and 55 km/h, i can feel and see the RPMs(techstream + bars in the eco meter)moving between 900 and 1200 in a pulse-like fashion on a straight and flat road. This does not happen at speeds above 55/60 km/h.

There are no codes. The car is about 194k KMs driven and maintenance has NOT been neglected. Would appreciate if i could be pointed in the correct direction to resolve these issues. @haseeb.basharat @Xulfiqar @syncview @capsat @Storm

[hassan4772]

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[Xulfiqar]

You may need to test the amp output of the battery unit, bad battery can show good voltage but die under amp demand.

Check the demanded parameters for CE operation, I think techstream doesnt show it, but its written in the repair manual.

[hassan4772]

@Xulfiqar so i think i found the culprits.

Frequent EV running:

I am still not sure how it got this dirty despite being serviced not more than 15k KMs ago.

Anyways, disconnected the 12V and the HV batteries to let the car "reset" (if it even happens), removed and cleaned the fan unit and the issue of excessive engine running is completely solved. EV mode kicks in and stays as soon as it can and for as long as it can. No excessive engine running when parameters are favourable e.g. coolant temperature, battery state of charge, heating requirement etc.

Engine Missing / Shudder:

I think i overused this set of spark plugs (about 120k KMs) ?

Could not source the OEM plugs immediately so temporarily put in a Chinese aftermarket iridium set. This has handled about 70% of the missing /shudder. I think the remaining 30% should be handled once i put in the OEM set?

Need guidance on whether i need to check the health/function of ignition coils as well? If yes, how? Any chances of those getting damaged due to the overused plugs?

During this activity, when i plugged in the VCI for the first time about a week ago, TechStream had stored a P0172 - System too rich in history. I cleared it and it did not return. Just wondering if i need to do something or at-least check the fuel injectors? How?

Thanks.

[Xulfiqar]

System too rich is indicative of a leaky injector or a bad AFR sensor too sometimes.

But good thing that you cleaned the fan,