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Toyota RAV4 over fueling

Posted by marius00cpt (My Page) on
Fri, Jan 9, 09 at 3:01

Good day. My 1999 Rav4 5dr 4x4 was in front accident. I am in South Africa, so this model is still same shape since 1994. It has 2.0i engine - the same as in Camry's in SA. This engine does not have oxygen / lambda censor.
Car is repaired, but fuel consumption is very high - 14 l/100km! CO is adjusted to lowest - down from 10% to 2%, but should be 0.5%. Tried to check resistances on CO-pot, water temp probe, air temp probe, etc, but appears normal. Throttle valverresistance does chance when turning it. Fuel return pipe to tank seems to be open. According to mechanics, fuel pressure is OK and timing cam position is correct. Another mechanic said the injectors stay open for the full duration during each cycle, implying they do open and close, but are staying open too long? or doesn't vary with engine revs / throttle valve position? Don't know if this is how it is meant to work. I do not have the values that the resistances of the various probes should be to compare to mine.
Any other suggestions? How does vacuum valve work - any influence on fuel?
Enjoy the day.


Follow-Up Postings:

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RE: Toyota RAV4 over fueling

If I've got my conversions correct, you are getting 16.8 Mile/Gal(US). I don't know what the US EPA rating is for this vehicle, but I'd expect more than 20 mile/gal. 16.8 mi/gal might be about right for rough terrain and staying in the lower gears, but you say the mileage is much less than before the repair.

Are you sure that you don't have an Oxygen sensor somewhere? Since you don't have to meet the US EPA exhaust emissions, you may not have a catalytic converter and the downstream oxygen sensor.

But since you have fuel injectors, I thought that the engine controller used the oxygen sensor to adjust the pulse width to the fuel injectors. Here in the States, when the signal from the oxygen sensor is missing, or out of range, the electronic engine controller uses default values for the injectors and these are on the rich side.

Has anyone read the trouble codes? Have any been set?

Does your engine control system use a temperature signal as part of its fuel management? If so, and if the engine controller is missing temperature informatiom, it may be staying with default settings for starting the engine.

Hopefully, someone on this forum is familar with the controls for your South African Toyota model and can help you.


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RE: Toyota RAV4 over fueling

To even begin to help, I have to know exactly how this vehicle is built. It appears that you are describing an early fuel injection system that I would associate with the 80's European cars here in the states. They used a vane airflow/fuel metering device and mechanical injectors. These injectors did not turn on and off, they actually sprayed fuel all of the time. The amount of fuel that they would deliver varied by the position of the air flow damper.

Now there are other systems out there as well, this is the first one I can picture that would vaguely fit the description you have given. If you let me know where in South Africa that you are, I may be able to hook you up with a tech that can deal with your cars problem.

One way you can attempt to do that yourself is with the member search directory for the iATN. If you find a techn on there near you, you can be assured he/she is one that is working really hard to be the best they can be. That person would also have access to all of the resources of the combined best techs around the world at their fingertips.

Here is a link that might be useful: The iATN


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RE: Toyota RAV4 over fueling

To jemdandy and john_g.
Thanks for your effort and inputs.
Unfortunately my RAV is different. I got it tested at another garage and they found no problems. All the sensors are working (there are no oxygen sensor) and the computer is responding correctly to various inputs. I end up let them put in a performance chip which enable them to manipulate the outputs to various inputs from sensors, and it was done on a dinatune machine. The result is a major improvement from the old 6-7 km/ltr to now 9.2 km/ltr which is more acceptable. I sold the car recently.
Thanks for your effort.
May God bless you.
Marius


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