Mark 2 Grande Weird Problem :(

[Nabeel_Ali]

AOA Members,

We Bought Mark 2 Grande 2004 a year back from a family friend.The car was fine but recently its really a pain in the ***.
The car starts with no problem, but as soon as it starts the car starts to miss and RPM's are not stable even the car goes off sometimes and a strong smell of petrol also comes from exhaust. This phenomena continues till the car's temperature reaches normal i.e the thermostat needle reaches between hot and cold!
I have taken my car to many Toyota Lahore outlets and those idiots over there don't know a thing :@ as they tuned the car about 1000 times and there is also no light of check engine so car's engine is fine!
Please help me out, I really need experts here

[Nabeel_Ali]

Any body??

[qwertypoiu]

Your car is CNG ?

[yasirsa]

change ur car thorttle body

[roonjha73]

Its acuallty not a problem, in case its normal, all modern cars have automatic choke when u start the car it comes in action till the engine temperature goes to normal that is as u mentioned b/w hot & cold. When the choke is working fuel mixture becomes rich which gives the smell and some a little bit of black smoke as the themostate valve starts working it shut down automatically.

[Xulfiqar]

one or two injectors are leaking, check for pressure stability in the system by running the fuel pump and shutting it down, Its only happening on cold startup because when cold the ECU ignores the O2 sensor and richens the fuel mixture by default ergo you will have no check light too.

[asad_188]

one or two injectors are leaking, check for pressure stability in the system by running the fuel pump and shutting it down, Its only happening on cold startup because when cold the ECU ignores the O2 sensor and richens the fuel mixture by default ergo you will have no check light too.

+1

[asad_188]

For the RPM drop and missing, do get the air intake pipe, fuel pump and the exhaust (Dholki) checked for the required cleaning.
Smell is due to rich fuel as mentioned in the above post.

[gundabunda]

Did any1 mentioned about changing its plugs?

[Xulfiqar]

if the plugs are bad - the engine will consistently misfire and it would set the CEL too.

[qwertypoiu]

he said its been tuned 1000 times so even a monkey would know if something is wrong with the plugs

[suneelmunj]

try contacting afzal at 03004777081 he will b able to solve ur problem inshAllah

[spectra]

Which engine. Is it AFM or MAP?

[ikrama1]

thorttle body problem hogi .. or ecu

[Nabeel_Ali]

Which engine. Is it AFM or MAP?

Can you explain this?

[Nabeel_Ali]

one or two injectors are leaking, check for pressure stability in the system by running the fuel pump and shutting it down, Its only happening on cold startup because when cold the ECU ignores the O2 sensor and richens the fuel mixture by default ergo you will have no check light too.

Thanks a lot will do this and let you know!

[Nabeel_Ali]

Its acuallty not a problem, in case its normal, all modern cars have automatic choke when u start the car it comes in action till the engine temperature goes to normal that is as u mentioned b/w hot & cold. When the choke is working fuel mixture becomes rich which gives the smell and some a little bit of black smoke as the themostate valve starts working it shut down automatically.

Its really a problem my uncle owns the same car and his is fine!

[Nabeel_Ali]

Your car is CNG ?

A year back it was, but as soon as we purchased the car we instantly removed it. At that time car was fine but recently it started to happen

[SER_GTR]

Possibly Leak Injectors Causing It Running Extra Rich Making Black Deposit On Plug Causing Missing And Unburnt Petrol Smell From Exhaust....

It Happens Till ECU Is In Open Loop And Running Independent..

Once It Hits The Close Loop And Started To Depend On Other Sensors Then Fuel Got Adjusted Taking Readings from Other Sensors.....!!

Agreed With Xulfiqar.....!! Also Make Sure You Water Temp Sensor For ECU Is Working Too....!!

[spectra]

Post picture of engine bay. If it is AFM then that can be faulty as well. For MAP it can be injectors as suggested.