Hello, i need some help please, I have a 2014 2.0 ford focus about 76k miles . It had around 3% on STFT and -7% LTFT . Now ive changed the spark plugs cleaned the MAF and throttle and its from +5 to -4 % STFT and around -11.5% LTFT. Need some advice where to look forward ,whats wrong
Clarification: Are you getting these readings at idle? Or at which rpms?
At idle , i tried to rev it up to around 2-2500 rmp but without a significant change
Try some fuel injector cleaners.
Already done that
Did you notice any change on the fuel trims afterwards?
Thats what i wrote from the beginning , its seems to be worse...actually i did the inje. Clean at the day of the MAF and throttle.
Ok, Are these values for the idle condition in a warmed up engine? If so, it seems that the injectors are still the issue.
Idle and warmed up..
How can i test them?
Try a few rounds of fuel injector cleaner when the tank is around half with a mix of some higher RPM driving and making multiple stops after the engine gets up to operating temperature. Scotty has mentioned the cleaner does best when the engine is hot and the cleaner is able to heat soak in the fuel injectors. Drive on the highway across town to a shopping center and shop, or do stop and go errands after it's had enough time to fully heat up. If the injectors are dirty, this should clean them up.
My 1999 Ranger has 277k miles, a few weeks ago it was starting to idle a bit rough with an intermittent LTFT of -11% on Bank 1 after driving 20 miles on the highway. Bank 2 was -7.8%. Cleaning the MAF, throttle, replacing the air filter and 4 rounds of fuel injector cleaner later, Bank 1 LTFT is running around -1.6%, while Bank 2 is 0% to +1.5% as of an hour ago. I drove exactly as I described. It can take a while for the cleaner to work if the injectors are really dirty.
Thank you Justin I will try that!
https://youtu.be/aDvtzg-ThZs
Is this a good method ?
I've never tried that, so I can't speak for it. Cleaners are safer. Try Scotty's new favorite cleaner. I forget what it's called. It's $20 a bottle. Maybe someone else remembers what it's called.
It’s the ATS fuel system cleaner:
https://www.atscarbonclean.com/