110 toyota Toyota 110 Fuel Consumption Issue

[Azmain Iqtidar]

I have a Toyota Corolla Ae110 which has run over 220000 km. I am not getting enough mileage even though I properly maintain it. However, I have changed my wheel size from 13 inches to 15. Is it the one that affecting my mileage? Need expert opinion. Point to be noted I have done full engine overhaul wiring etc. and the previous owner ran the car with cng too.

[matroska]

2 hours ago, Azmain Iqtidar said:

I have changed my wheel size from 13 inches to 15. Is it the one that affecting my mileage? Need expert opinion. Point to be noted I have done full engine overhaul wiring etc. and the previous owner ran the car with cng too.

What exactly is your expected mileage?

Yes changing wheel size can affect your fuel economy.  what was the initial fuel economy you had - did it drop? Or simply you're not getting the mileage you expected.

A few things to test would be the condition of your plugs, if your sensors such as Mass air flow sensor, O2 sensor etc  are working properly. A faulty ECU could also be the culprit. 

[iRage]

Well...have you noticed a drop ? If so was this before or after the overhaul ? When was the overhaul done ?

As matroska asked, what fuel figures are you expecting ? What was the fuel figure you were getting and what are you getting now ?

What exactly is your car ? What engine does it have ? What is the transmission ?

Changing wheel size can affect fuel consumption but it is quite small. Again, we won't know what the drop in fuel efficiency in your car is to say if its due to the wheel change or not.

Apart from the sensors going bad...everything from the fuel pump to the fuel lines to the EVAP system to the transmission to the brakes to the condition of the tires/wheels all effect fuel efficiency. So there is no way to say anything.

[Gummybr]

Dont expect fairytale fuel fuel figures just because its a Toyota, when I had mine it did only around 8-9 city. If someone says that it should do 15kmpl forget it. 

[Azmain Iqtidar]

I expect 10 in the city and 15 in the highways. I have checked with several mechanics, who said the sensors are working fine. There is no engine check light. No unusual vibrating or sound. One said the tappet clearance needs to be done to get good mileage. I also don't know the actual wheel size located on the car door with a sticker coz the sticker is not there. 

what was the initial fuel economy you had - did it drop? Or simply you're not getting the mileage you expected.

The car ran with alternative fuel for a long time. I changed it to the original form after doing an engine overhaul. Yet the fuel economy was very low. So I changed the injectors resulting in a better fuel economy but not that good. Say previously I got 3-4 but after changing the injectors getting 5-6.  

[matroska]

10 hours ago, Azmain Iqtidar said:

but after changing the injectors getting 5-6.  

So going for 15 inch wheels will not affect that drastically. I have to admit 5-6 is quite low if that is your current fuel consumption. While I'm pretty sure there has been some mess-up done during the alternative fuel switch. 

Not just the sensors, it might be the transmission, even a faulty ECU. Sadly this is a rather vague situation.  You mentioned 'wiring' even some improper wiring could be a culprit. 

[iRage]

10 hours ago, Azmain Iqtidar said:

Say previously I got 3-4 but after changing the injectors getting 5-6.  

When did you do the overhaul (also what do you mean by overhaul)? Depending on what you actually did, it might need time for the engine to break in. Also, how is the transmission? Does it slip? Assuming that there are no other significant factors like brake binding, under-inflated tires, super grippy tires, or the fact that you drive in the midst of the thickest of heavy traffic times. 

But year...maybe you do need to do some simple adjustments to the engine as well. Also, LPG cars, when run over a period of time, especially with sub-standard systems that we had, result in things like valve seat recession, which results in off-spec tappet/valve clearances, etc....did you get all these checked and put back into spec during your overhaul? Do you smell burning oil at the exhaust? or even have smoke coming out?

Did you reset the ECU ? When you reset it and it has learnt the defaults, does the car act normally and feel like it runs more efficiently and then slowly start to become fuel inefficient over a period of time ?

EDIT : Also, did you put the right fuel injectors? The ones with the stock flow rate, etc..or a set that is "compatible" ?

If your car is a DX, LX or XE Saloon it would have originally come with 13x5J wheels with 155SR13 tires (equivalent to 155/80R13 or so). If it was a SE Saloon then it would have come with 13x5J wheels wrapped in 175/70R13 tires or come with the optional 14x5.5J wheels with 175/65R14 tires.

 

Edited May 13 by iRage

[Azmain Iqtidar]

The engine overhaul was done in Jun or July 2023. There is not a single problem with the transmission. It shifts smoothly. I drive in the worst city in the world called Dhaka.

It was not run on LPG but rather CNG which was very harmful for the engine. I did not get all these checks during the overhaul but I am ready to do it now. No burning oil smell and the smoke is not that visible. 

The ECU has changed. The original one I looked up online and found a part code 89661-1A440 where my mechanic installed 5aFe ecu but the part code is different and I don't know which car it is from. The part code of the ECU in my car right now is 89661-12710. 

I could not find the original fuel injectors so I put the one compatible. It is maybe a Chinese one.

I guess the right wheel size of my car is 165 80 R13. Also, I want to know what SR means. Like 165 SR 13. 

So I came up with an initial fix that I have to change the ECU, the injectors to the original ones, and the wheels to the original size. Maybe that will fix the fuel consumption issue. What do you think?

 

 

Edited May 13 by Azmain Iqtidar

[Gummybr]

@Azmain Iqtidar the figures of 8-9kmpl I posted was about 15 years back when the car had done 115,000kms, it still does around that much even with more than 300,000kms on the clock. It all depends on how you drive, what kind of traffic conditions and the terrain you drive. 

You need to change the gearbox oil on time, change engine oil on time and do the necessary maintenance on time to have the car running smoothly. As you have mentioned where you are driving and the CNG conversion I suggest you try changing your driving pattern and habbits first then look at the more expensive work on the engine.

[iRage]

15 hours ago, Azmain Iqtidar said:

The ECU has changed. The original one I looked up online and found a part code 89661-1A440 where my mechanic installed 5aFe ecu but the part code is different and I don't know which car it is from. The part code of the ECU in my car right now is 89661-12710.

The ECU should be fine...depending on the market and the supplier sometimes the same ECU has slightly different numbers. The ECU right now seems to be compatible with E1xx Corollas with a 5A-FE engine.

Now that you have aftermarket injectors (which may or may not be to original spec) and a new ECU...did you try to remap the ECU ? It could be that the fuel mixture is too rich as well. Did you do any kind of eco test and read the emissions?

Before going and replacing all of these things...do some basic diagnostics and try changing simple things...time you drive...your driving style, etc... 13 to 15 inch wheel change should not drop your fuel efficiency THAT much.