johnbil

Hi All,

First post and a call for help,

I've an Australian 1999 LX 470,
Economy is over 30 liters per 100, (city) I think the conversion is around 7 MPG,

The A/F ratio is constantly around 11 while cruising, and naturally dips under acceleration, , (measured with an Innovate LM2)

I've adjusted the TPS, hoping to raise the A/F ration, but no effect, only idle is affected, and after removing the battery lead and reconnected lead, the throttle control motor brings the idle back to normal.

Also strange that this model was imported to Australia without O2 sensor up or down stream, so no closed loop efi.

My question is how to raise a/f or lean fuel burn,

Im thinking of installing a variable fuel pressure regulator on the return line to drop fuel pressure to the injectors, not ideal, but how else can I adjust fuel delivery,

Is there some way of changing the mapping other than changing the pulse duration using 3rd party chips?

Lexus tech in Australia thinks theirs a pot to change mapping, but as the cars getting on, he cant remember where the pot is?

I've not read or seen any proof of this.
Any way thanks for reading the post. Great site.

Regards John B

johnbil

Works a treat,


50K linear pot and resister in MAF signal to ECU,
Running at a nice A/F of 15 while cruising.
will post fuel savings if anyone interested?
Cheers JB

johnbil

1800 km traveled hwy cycle, Cairns to Brisbane, averaged 13.3 liters/100.
City cycle 18.5ish liters /100.
Don't need to sell the car now,
jB

fastnoypi

nice work around with the linear pot! Before attempting to intercept signals, usually closed loop fueling problems are the effect of either a front o2 sensor going out or debris/oil contaminating the maf sensor. CRC maf or electronics cleaner for the maf helps in some cases.

TimboTango

Hi JB
I am a newbie at CL.
I own a 2003 LX470 and was wondering if the above liner pot mod you mentioned will fix my poor fuel economy also?
Plus how do you know where to set the pot at?

Cheer Tim

LX4702003

I think poor fuel economy is par for the course in the LX. Though my 2003 gets around 14 mpg highway.