Petrol Use Averaging Computer Rav4

[FPLANOT]

Having just had my RAV4 - XTR Auto (2005) serviced by the main Toyota Agent and having advised that the 'trip computer' has started showing 99.9mpg (average).... I was advised that this is normal. However as this value has never 'shown itself' in the past 4+ years...... I feel this answer is incorrect. I am aware that the readings obtained (even when working correctly) are 'way-off' the real consumption levels ... having only obtained 'brim-to-brim' consumption (averages) of 24mpg around town and a maximum of 32mpg on good runs (combined). If anyone has any further comments or has had similar situations develop with their Toyota 'trip' computers (other than comments already posted pre 01/07/2010) I would be pleased to read them.

Thankyou.

[shcm]

Welcome to TOC!

I suspect you are right and the dealer is either wrong or confused.

OK, I only ever had a 2002 4.2, but I'm assuming the 2005 still has the trip info displayed on the radio/head unit?

Just to state the obvious, yes, 99.9mpg is commonly seen on instantaneous and you can sometimes get 99.9mpg up on average for a short time, if you do something like reset the reading and then over-run down hill for a few miles or so. I'm sure you are aware of all that anyway.

If I remember correctly, the vehicle speed signal and an equivalent fuel injector drive signal (fueling pulse) is fed into the head unit. From these (and some timing) I expect it can calc approx fuel consumption.

I wouldn't be surprised if the radio/head unit is no longer seeing the injector pulse signal, either through a wiring(harness) fault, a corroded/unseated connector (very often this is just the problem), a fault in the headunit itself or possibly a fault with the fueling pulse output from the engine management ECU to the headunit. I would think that no fueling pulse to the headunit would make it think no fuel was being used and give a very high mpg figure - like 99.9mpg.

[bothwell_buyer]

dear fplanot

welcome to this forii where abundant useless information is posted by myself in copious bundles.

If I had a car registering 99.9mpg, I'd get it onto eBay quick to sell it to someone needing an economic car!!

Or say to the dealer that they've dissed a wire.