1994 LS 400: how do i improve my gas mileage?
03-23-14, 03:08 PM
#16
Lexus Champion
03-23-14, 05:28 PM
#17
Moderator
Cheating the ECU is another simple and smart way to improve the gas mileage for a guy who is comfortable to play with a soldering iron. ECU controlled engines can be improved the gas mileage using a electronics method.
Usually pre-cat O2 sensors give the ECU the swinging voltage of 0 to 900mV. You just give the bias voltage of 375mV to the ECU and the voltage at the O2 sensor line becomes 375mV to 900mV+. The line never goes down below 375mV and the ECU considers the A/F ratio rich and reduces the injection time. This is just a simple and easy way to get the improvement about 8%. You will be amazed at how simple and effective but this requires you to deal with electronics circuits all by yourself with your own skill and the responsibility.
Usually pre-cat O2 sensors give the ECU the swinging voltage of 0 to 900mV. You just give the bias voltage of 375mV to the ECU and the voltage at the O2 sensor line becomes 375mV to 900mV+. The line never goes down below 375mV and the ECU considers the A/F ratio rich and reduces the injection time. This is just a simple and easy way to get the improvement about 8%. You will be amazed at how simple and effective but this requires you to deal with electronics circuits all by yourself with your own skill and the responsibility.
Last edited by Yamae; 03-23-14 at 06:01 PM.
03-23-14, 05:45 PM
#18
Lexus Champion
Cheating the ECU is another simple and smart way to improve the gas mileage for a guy who is comfortable to play with a soldering iron. ECU controlled engines can be improved it's gas mileage using a electronics method.
Usually pre-cat O2 sensors give the ECU the swinging voltage of 0 to 900mV. Give the bias voltage of 375mV to the ECU and the voltage at the O2 sensor line becomes 375mV to 900mV+. The lines never go down below 375mV. This is just a simple and easy way to get the improvement about 8%. You will be amazed at how simple and effective but this requires you to deal with electronics circuits all by yourself with your own skill and the responsibility.
Usually pre-cat O2 sensors give the ECU the swinging voltage of 0 to 900mV. Give the bias voltage of 375mV to the ECU and the voltage at the O2 sensor line becomes 375mV to 900mV+. The lines never go down below 375mV. This is just a simple and easy way to get the improvement about 8%. You will be amazed at how simple and effective but this requires you to deal with electronics circuits all by yourself with your own skill and the responsibility.
if there is no disadvantage, why did Nippon Denso not do this?
03-23-14, 06:30 PM
#19
Moderator
The disadvantage is a bit poor acceleration because the the A/F ratio becomes lean. I almost don't notice it with my Celsior but my wife's car Avensis which has a 2L 3S-FE engine shows some lesser power only at the slow acceleration. In case of a quick acceleration, it doesn't show any noticeable difference may be because of the sub routine job done by the ECU to provide richer gas.
Car manufacturers are using this technique not by the bias voltage but the software. But the software is not often as effective as my method, I understood doing experiments applying the method to many different cars.
Car manufacturers are using this technique not by the bias voltage but the software. But the software is not often as effective as my method, I understood doing experiments applying the method to many different cars.
03-23-14, 06:51 PM
#20
Yamae, I have a good ECU sitting on my shelf next to me... would love to try it, even if I fry the ECU as I have a good one in my car already. Since both ECUs have never been modified, and they both work great and give identical performance in my car, I could also do an A to B comparison just to see what kind of improvement could be achieved. My feeling is that my car takes too much gas on slow acceleration. This could also be due to (possibly) broken EGR pipe though...
Can you enlighten us as to what would need to be changed in the ECU to achieve that increase in voltage that pre-cat O2 sensor sends?
(my car is 1990 LS400, California emissions)
Can you enlighten us as to what would need to be changed in the ECU to achieve that increase in voltage that pre-cat O2 sensor sends?
(my car is 1990 LS400, California emissions)
02-18-15, 10:47 PM
#21
Lead Lap
Join Date: Jun 2008
Location: indianapolis
Posts: 421
Likes: 0
Received 0 Likes
on
0 Posts
The disadvantage is a bit poor acceleration because the the A/F ratio becomes lean. I almost don't notice it with my Celsior but my wife's car Avensis which has a 2L 3S-FE engine shows some lesser power only at the slow acceleration. In case of a quick acceleration, it doesn't show any noticeable difference may be because of the sub routine job done by the ECU to provide richer gas.
Car manufacturers are using this technique not by the bias voltage but the software. But the software is not often as effective as my method, I understood doing experiments applying the method to many different cars.
Car manufacturers are using this technique not by the bias voltage but the software. But the software is not often as effective as my method, I understood doing experiments applying the method to many different cars.
Could you explain how to do this?
02-21-15, 05:07 PM
#22
Moderator
The most simple way is introduced here below.
The best way is to use an IC for a VU meter but the method above is also effective some.
By the added voltage to the O2 sensor, the ECU judges the gas amount too much and reduces it and the gas mileage is improved.
By the added voltage to the O2 sensor, the ECU judges the gas amount too much and reduces it and the gas mileage is improved.
02-22-15, 07:53 PM
#23
Throw some gas additive in your tank before every oil change and do an Italian tuneup. But how you drive an make a difference especially in city driving. I can get 14 or I can get 21 in city driving depending how hard I accelerate, how short my trips are (a cold engine is less efficient) ect..
06-01-16, 07:09 PM
#24
Intermediate
as far as getting better mileage, here is what I would do in order of how much difference it will likely make:
● make sure your tires are kept inflated to 32 psi cold, or slightly higher, and if the tires are over 4 years old, replace them for both mileage and safety's sake, time wear tires as much as mileage does!
● replace the engine coolant temperature sensor with the factory OEM one from Sewell Lexus or other online dealership
● replace the thermostat with the factory OEM one from Sewell Lexus or other online dealership
● replace the wires and plugs with genuine NGK or Denso from amazon or rockauto.com
● replace the distributor caps and rotors with the factory OEM ones from Sewell Lexus or other online dealership
● replace the O2 sensors with genuine Denso from rockauto.com or amazon
● get a good 4 wheel alignment
● make sure your tires are kept inflated to 32 psi cold, or slightly higher, and if the tires are over 4 years old, replace them for both mileage and safety's sake, time wear tires as much as mileage does!
● replace the engine coolant temperature sensor with the factory OEM one from Sewell Lexus or other online dealership
● replace the thermostat with the factory OEM one from Sewell Lexus or other online dealership
● replace the wires and plugs with genuine NGK or Denso from amazon or rockauto.com
● replace the distributor caps and rotors with the factory OEM ones from Sewell Lexus or other online dealership
● replace the O2 sensors with genuine Denso from rockauto.com or amazon
● get a good 4 wheel alignment
.So you think it would be a good idea to replace all 4 o2 sensors.... Well, the car has done nearly 300,000km....
06-01-16, 08:09 PM
#25
To improve economy thin hard tires for one. No drastic suspension system modifications, the extreme camber adds more scrub and friction. A good alignment. A fuel that lacks alcohol, I guess that was covered. A good aftermarket power train control system that is fully user programmable. Installation of a small diesel engine instead of a v8, constant use of cruise control. Just some ideas I can think of that can help fuel economy.
Thread
Thread Starter
Forum
Replies
Last Post
bowen.chau
RX - 1st Gen (1999-2003)
390
11-19-23 09:00 AM
