Multiple misfire when starting.
The car fluctuated badly.

When you apply the brakes, it returns to normal
When the brake is release, the problem occurs again after a while.

What's the problem?

 

Hello,

Probably a vacuum leak. Get a smoke test done. Also have a proper engine diagnostic scan for codes. You have not provided sufficient information to allow a proper diagnosis at this time. Follow up with the requested instructions and we can further discuss this situation.

E

 

I recently repaired all vacuum leaks in the vehicle.
This symptom only occurs during cold start.

When the coolant temperature reaches 90 degrees Celsius, symptoms no longer occur.

The diagnostic device generates two codes.P010B Code: Mass or Volume Air Flow “B” Circuit Range / PerformanceP106A Throttle valve position mismatch

 

My impression is on cold start the ECU uses a fixed MAP in closed loop until the system goes to open loop monitoring. In open loop the problem is compensated by the fuel managed open loop protocols.

The MAS air fault is an indicator and not necessarily the sensor. You or your mechanic need to investigate. The brake pedal application to smooth out the idle is compensating the vacume volume temporarily improving the idle.

I would be looking for a small air leak.

 

Unfortunately, we didn't find any vacuum leaks today.
In the end, the technician suggested a $7,000 engine repair.
Thank you.

 

If the Tech guy is going to repair it ...what is the fault he is going to repair for 7K bro ?
As you dont say ..I would make sure he can cure it before i would let him on it myself ..goodluck bro

 

He suggested rebuilding the vacuum line and intake line, various gaskets and ignition devices by removing the engine and mission.

 

What happens if you remove the oil filler cap whilst engine idle ?
The other vacuum system separate from the vac system on top of the trans is the oil breather and separator. It pulls its own vacuum from the inlet manifold and the low pressure inlet side of the turbo.

 

The oil filler lid does not open well.
I feel like the wind is being sucked in.

 

The oil fill tube fitment may indeed be the vacuum leak. A small amount of "wind".. un-metered vacume entry there could create and [or] contribute to the issues that your vehicle is exhibiting. FIX this first before spending $7000.00 and engine out.

 

@Frank ( Sunnyside )
@1eapplebaum

Sounds like the way to go for me $7000 is alot of money ..well to me it is

 

I looked again for the vacuum leak of the oil cap and dipstick, but I didn't solve the problem.

The vacuum pressure of the intake manifold remains at -22inHg and there is no change when the brake is applied.

I mobilized screen test, parts cleaner, and soapy water, but I couldn't find any vacuum leakage.

One characteristic is that after parking the car and about half a day, the brake pedal hardens.

 

Correct me if I missed it, but have you done what 1eapplebaum suggested and carried out a full smoke test.
ie remove front left wheel and liner. Disconnected the line to the accumulators and pump your smoke directly into the vacuum system.
Give it plenty of time for the smoke to circulate the system.

 

The brake pedal will get firm even after a few hours. That is normal to all cars.

The vacuum leak is most likely small. I suspect the vehicle runs normally when the coolant temperature sensor allows the ECU to manage the fuel trims. A large leak would signal the ECU to throw different trouble codes. One cau scan the fuel trims with VCDS. The trim values if too lean (vacume leak) can confirm my suspicion.... or not. 😏
Perhaps your mechanic can perform this test and than post the results.

 

I tried again, but I didn't find any vacuum leak

Maintain 600 RPM at idle, 2.4g/s intake air, and -25inHg intake manifold vacuum pressure.

Rough idle, Is this vacuum leak?