₦airaland Forum

some person here might probably be wondering what a vacuum leak is.....
The MAF sensor i.e mass air flow sensor measures(meters) the amount of air entering into the engine. IAT sensor, air inlet temperature sensor measures the temperature of this inlet air to the engine. Driver can manually varies the amount of air entering the engine via a throttle pedal.
how does the ECM, engine computer module knows this it uses TPS, throttle position sensor. the ECM then increases the pulse rate of the fuel injector.....bla bla bla..... to achieve stoichiometric air fuel ratio...lol
The computer(ECM) uses Pre CAT O2 sensor B1S1 for a single bank engine e.g I4 engine or B1S1/B2S1 for dual bank engine e.g V6 engine to measure the A/F ratio of the exhuast gas. this feedback is necessary to control........too much story

Back to vacuum leak..... any air into the engine post MAF sensor is not metered or measured. The ECM does not know this. what it sees is the O2 voltage reading. B1S1 voltage reading will shows a lean condition i.e too much air in the exhaust. The ECM based on this signal, increases injectors' pulse rate for the next power cycle meaning u will be burning more fuel than is required.
how do you know this ....fuel trims

@ makarios911, you need a scantool that has livedata facility.
to check for vacuum leak, you need a smoke machine, or scantool + propane touch method
What i would normally do, i set my scantool to displace long term fuel trim(LTFT) for both banks. With the car idling, i open the throttle to about 2500RPM or more. If it's a vacuum leak, i should see my LTFT drop from positive %value to close to 0%. The rationale behind this is that at high rpm, the effect of vacuum leak becomes less significant. Hence your car may probably have good gas milage on highway but very poor one in the city

understanding fuel trims:
https://www.youtube.com/watch?v=5WnM_NsOtd8

from the data you provided, u can calculate your MPG. check against factory value 21/27 city/high way for a 2007 rav 4 FWD I4 2.4L engine. V6 engine will comsume more fuel.
In simplicity conventional car consumes more fuel within city than high way, for the above example 21MPG in the city and 27MPG on highway. To get better gas milage, you need to scan ur car, check that your long term fuel trim is close to 0% as possible. The fuel trim shows the % deviation from OEM source code. For a car that has 20% long term fuel trim, it means the ECU will add 20% extra fuel for each power cycle.
You need an advance mechanic to restore your long term fuel trim if it is out, not road side mechanic, never!

Avoid excessive use of your AC
change your engine oil with synthetic oil
Accelerate gradually(car consumes more fuel at kick off and stop), avoid hard braking
avoid unnecessary idling.
change your inlet filter frequently......
change your PCV if clogged
get correct tire pressure. under inflated tire results in excess fuel consumption.
......the list is endlss

Experience4u:
Thanks for the detailed analysis and your help for a follower enthusiast. Please I want to know if what am getting out of my car is OK. With a fuel tank of 58litres I get about 270miles out of my full tank on highway driving whereas I get less than 180miles while driving within town on my Rav4 2004. please what can I do to get a better mpg. Thanks

respect @ GAZZUZZ, hope i haven't broken any rule in ur thread. i'm here to help as well

for poor gas milage, you need a scantool that has live data functionality.
1. run a scan and scan if there's any present malfunction or historical trouble code
2. Check your live date. You want to be looking at your fuel trims. short and long fuel trim. you want to be close to _+0% on your long term fuel trim LTFT
3. for your case i believe you are probably running rich you should be between 20 - 24% negative long term fuel trim. This will lead to diagnose if u have a vacuum leak, poor fuel injectors, dirty MAF sensor etc
4. your short term fuel trim tells u the instantaneous pulse rate of the fuel injector/ fuel pump performance. can diagnose dirty fuel pump filter or clogged injector
5. exhaust leak may and may not be significant. Post B1S2 exhaust leak is less significant in fuel economy. Exhaust leak before before the B1S2 will cause excess air into the exhaust and ur O2 sensor voltage will be rather low close to 0.1V.
the list keeps on going till infinity...... IAT sensor reading, RPM vs cycle load, spark plug misfire live data, alldata repair manual

i'm an advance DIY, trained online by scannerdanner, subscriber to ericthecarguy, schrondinger, chrisfix, scotty kilmer on youtube.
i stay around PH environ but i'm not always available because of work. I do diagnosis for almost free. ADVANCE diagnose if u know what i mean and can program auto key for almost a token with my powerful skp-900 key programmer. I use toyota intelligence, toyota techstream and autel maxicheck for my diagnose. I have maxidas708 but for paid diagnose only

I4 engines gereally have two oxygen sensor and cat converter is bween the two O2 sensor.

Intelligent people here but sometime you might need more than just a guess. Cat available or not. Like seriously.! You don't need diagnostic tool to check that. Simoly follow the exhaust manifold from the engine. U shud see the first oxygen sensor A/F ratio sensor. Very important and more expensive than the other post cat converter.

fixmykey:
U need to get a tool that can reset the immobilizer box of the Toyota, Lexus, Prius or Scion and also get a seed number calculator.
I guess you are a programmer?
I can get you tools that can execute the task. NOTE: You must not re-flash used toyota smart keys to have them reused.
But for Landrover and range rover YES etc.
Call 08138389434
Call 08023977522

toyota techstream has the facility to do it but seed calculator for toyota/lexus/scion is expensive(aliexpress). If u have SKS calculator, then i can pay that service alone.

Unfortunately my SKP-900 don't have that facility

Toyota smart key. Two in number

I have two keys that have been previously programmed. I need a flashing service to enable me reprogram them

you have a mail from me. Kindly respond ASAP. My mobile network is down.

koolkesh:
Expecting your call.

i didn't see it that it is a naija used.

THIS IS THE BEST PRICE I'VE SEEN ON NAIRALAND. TOO GOOD TO BELIEVE.
I WILL GIVE YOU A CALL

Scammer. This ridea was advertised by another auto dealer

Location pls.

location?

location of the car? Can you provide VIN pls?

Hope it's an AWD

I will call you in the morning

how much for this beast?

glasshouse:
Available for inspection

na AWD?

Is the Benz 4matic?

Where is this car? I'm much interested

very nice job. where is your location and how much will it cost to do for corolla, leather seat and dashboard?

osama10, this is where u shud bring ur purchase to.
I'm still awaiting a good deal on my RX300.

CALCULUSX is the name when it comes to pre-order.
It's not an advert, check his profile and thread.
Calculusx all the way....

ok bro. AWD oooooo