Corolla 2004 SE saloon 1.6 AT . Bad fuel average getting around 5 to 6 KM/L

pwuser165894284162 (Hammad Iftikhar Ahmed) 2022-08-31 20:24:39 +0500 #1

I have recently bought 2004 Toyota Corolla Se saloon 1.6 At
Overall the car is in really good shape and condition (the engine health is good however i am getting really bad fuel average
Also I am facing misfire or jerk when my car hits around 100 Km/h and engine check light appears upon slowing down the speed from 100km/h the jerking and check engine light goes away
1st time I got it scanned no error found. 2nd time i got it scanned right away the check again light came it showed an error coil issue (ignitor)

Note : The mechanic said is mai coils mira gari kai dalae huay hain

I did the basic tuning but the fuel consumption is still the same approx 6km/L on 50% AC

Changed engine oil (used Toyota 20W50)
Changed Oil filter and Ail filter (leppon)
Spark plugs cleaned
Coil cleaned
MAF sensor cleaned
Throttle body cleaned

What should I do to get better fuel average ?

xenerking (xenerking) 2022-08-31 21:26:49 +0500 #2

u already know the reason, replace coils with OEM.

ur car has manual trim pot for AFR, if its fiddled with then use exhaust gas analyser to adjust according to factory specs.

pwuser165894284162 (Hammad Iftikhar Ahmed) 2022-08-31 22:44:56 +0500 #3

Thank you for the advice.
What is manual trim pot for AFR ? And what is exhaust gas analyser ?
I am not quiet familiar with these things

xenerking (xenerking) 2022-09-01 00:20:35 +0500 #4

there is an potentiometer which can adjust the AIR TO FUEL RATIO manually, just like a volume control.

The exshaust gas analyzer is a device which measures the CO/ CO2 and other exhaust gases from the silencer tip, it helps to adjust the AFR of car.

rest u can google and build ur understanding on it

pwuser165894284162 (Hammad Iftikhar Ahmed) 2022-09-03 04:40:06 +0500 #5

I replaced the ignitor coils and spark plugs the results are,
no more rough idling, Jerking with check engine light on high speed gone .MAF sensor serviced
However the average is still not 100% good because its consuming more air and fuel on the same power as the fuel and air ratio is 3.5mm (scanner result)however its has to be below 3 mm
In order to reduce to the ratio we tried putting new MAF sensor but the outcome was still the same 3.5mm.

xenerking (xenerking) 2022-09-03 07:21:32 +0500 #6

check near the front strut mount in engine room, u might find a potentiometer to adjust AFR, dont fiddle with it if its a factory position