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Robert, UK Car Mechanic
Category: UK Car
Satisfied Customers: 4639
Experience:  Fully qualified / self employed garage technician in the UK
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I have a Toyota Yaris Verso 2004 ODO ~130000 km. Problems

Customer Question

I have a Toyota Yaris Verso 2004 ODO ~130000 km. Problems are it have high consumtion of petrol: 0.85-0.9 l/10 km - Before it was during same circumstances 0.45-0.6 l/10 km. Sometimes the Engine goes "weak", without Power as it was only running on 1-2 cylinders. Then it might stop totally, but will eventually run again after some time of resting. It will Always start when Cold, but when its hot - its a gamble.
JA: Has the vehicle turned into a gas hog? And how does it start -- same as usual?
Customer: I have changed the censor for "air-amount-messuring", lambda probe, spark plugs, impulse sensor, new fuel pump etc, etc. I had in in for repair at Toyota, but no change.
Failure codes have been: P0171What can the cause to these problems be
JA: Are you fixing your Yaris yourself? What have you tried so far?
Customer: Read above please...
JA: Anything else you want the mechanic to know before I connect you?
Customer: Before this change in behavior, I lost my keys and Toyota replaced the cars computer with a new one - they said it was nessesary for the new keys.
Submitted: 1 month ago.
Category: UK Car
Expert:  Robert replied 1 month ago.


I persume by "air amounting messuring" you replaced the MAF (mass air flow meter) is it aftermarket or genuine?

Is the the only code set P0171?

Fuel pump did you replace the fuel filter at the same time?

Customer: replied 1 month ago.
Its genuine original mass air flow meter. As I said Before - I have tested two other MAF except the one I did replace. Three MAF´s didnt do any change.
Yes - new filter and the new fuel pump have been tested for correct pressure - no problem.
Expert:  Robert replied 1 month ago.

Yeah cause low fuel pressure can cause that code to flag if fuel pressure is normal and holding,the MAF is genuine.. you've ensured that you have not got any exhaust leaks especially before the upstream o2 sensor...have you had them check for vaccum and intake leaks..that normally has to be one things top of the list to be checking out..ideally i would advise the use of a smoke machine to fill the intake aswell as the vaccum system on the engine to help identify any leaks..if that hasnt been done yet..then id advise that being the next could be looking at leak in one of these off setting the fuel tirm because it see extra unmetered air so the fuelling will increase to compensate for data on scanner looking at LT fuel trim and O2 sensor live data would maybe show that..