Hello everybody. I have a Suzuki Swift 1.2 vvt engine with 94Hp.
Lately I have been getting higher gas mileage and also the fuel trim is between -15 and -20%.
The injector have been professionally cleaned and tested, they are in perfect working condition, spark plugs almost new, ignition coils new, all sensors on intake and exhaust are new.
My question is: Could the timing affect the fuel trim? The car has 260k km and the original timing chain. There is no typical chain noise on cold startup to indicate a worn up chain.
On idle the ignition advance oscillates between 5 and 14 degrees, not sure about the stock values as I cannot find any information regarding that.
Should I consider a new timing chain? Or, what else could cause this.
Thank you all,
Best regards,
Adrian
Of course the timing can affect fuel trim. Ask can of worn out engine so do a wet and dry compression test of the engine to see if the piston rings are worn out. Also check out the mass air flow sensor. It could be bad
I'll check the compression.
The MAF, MAP and oxygen sensors are almost new (2-3000 km) but the problem was before changing them
Coming back with an update, I bought my self a cheapo compression tester (25 USD).
Tested today dry and wet test and all came to 90 PSI.
I know 90 psi is low but the cylinders were all pinned at 90 psi dry and wet so I am not sure about the tester to be honest.
The reason I don;t believe it's just 90 psi is because the engine starts right up, even in temps of -25 degrees Celsius ( -13 fah) which we get in my region in the winter. I am from Roumania, Europe by the way.
Next time I go to my mechanic I will ask him to test with his equipment to see more accurate values.
Also, here is a picture of how the spark plugs look. Not burning oil from what I can tell. https://ibb.co/GvnP9NW
use the direct image links (right click image - copy link) so it shows up
the plug looks great
Something weird just happened. Changed the oil because it was its time, and added the correct amount of Liqui Moly Ceratec to the engine. After like 150 miles, the fuel trim hovers now around -3 to -5 and the car feels a lot smooth. Not sure what the ceratec has to do with it, but it seems like it did something.