# Electronic Fuel Injection Inhancer power source.

#### MazdaCarnage

Joined Apr 26, 2020
7
I have been running a basic homemade EFIE on one of my cars similar to this:

The narrow band O2 sensor on this car is a single wire Zirconia sensor that generates a 0 -1v dc signal to the ECU.
I no longer want the EFIE controller to be powered by a disposable battery. From what I read when originally making the EFIE controller the power source has to be completely isolated from the cars 12V electrical system. I do know zirconia oxygen sensors are easily shorted by any positive current feedback.

I have a few different ideas about using a rechargeable power source and either a solar panel or battery charger and 2 Double Pole Double Throw relay to control connections between charger to AA battery and AA battery to EFIE controller.

Positive :Battery charger ------ N.C. side of relay 1------ AA Battery ------ N.O. side of relay 1------ EFIE
Negative:Battery charger ------ N.C. side of relay 2------ AA Battery ------ N.O. side of relay 2------ EFIE
Relay coils energized by ignition switched 12v + signal.

With a solar power source I think only the Positive current side would need to be wired through a relay. But I would rather not have to install a small solar panel in the car.
Can double pole double throw relays fail with both throws active?
Is their a current drain from a smart charger when it isn't charging a battery? If so how much?
(Questions that just came to mind).

So I have looked at smart battery chargers and making your own, types, sizes and outputs of rechargeable batteries... I have read many DIY write ups about all kinds of charging, solar, custom electronics, voltage isolation, signal isolation... but haven't been inspired by any alternative ideas. Most of what I find is not relevant to my specific application.
The world of electronics is so vast. Normally if I am looking for a solution or direction I find a similar example online, learn the components function, and how everything works and go from there. I am having a hard time finding a starting point that doesn't involve a AA battery. And all I can think to do is replace the disposable battery with a rechargeable battery and set it up to autocharge. I don't think this is the most durable or reliable solution and I don't feel it's fail safe for the Oxygen sensor, meaning it could fail and damage the O2 sensor.

I decided to ask the experts for a better way.
This is one of many hundreds of things I am doing on the car and seems like one of the simplest of those things but is proving to be most challenging.

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The following has nothing to do with the above question but is about what the EFIE ties into and some of the other things on this car.
It all started when I purchased an expensive used Water / Alcohol injection system for one of my other cars, I decided I was going to make my own water / alcohol system for this car out of parts I had lying around.
I researched every popular system on the market, I found DIY set-up of all kinds and came up with my own system.

Alcohol, methanol, methyl hydrate require specific materials that can withstand them. The electric pump is the most expensive component of the available systems and the most prone part to fail.

I found DIY's where people used pressurized air tanks to pressurize the liquid in the system, as tank pressure dropped so did liquid pressure.
Another who used boost pressure from the engine to pressurize his system but in order to inject one pressurized substance into an evenly pressurized environment requires an expensive misting nozzle and elaborate pluming.
I decided to use an electric air pump to pressurize my system. I had a small broken air compressor, some small lab tanks, a liquid pressure regulator, braided high pressure stainless hose, solenoid valve, fittings and misting nozzles. I purchased a small permanent mount 12V air compressor.
Air compressor----air tank----air pressure regulator----liquid tank----liquid pressure regulator----accumulator tank----Braided hose----solenoid valves----misting nozzles.

The solenoid valves are activated by pressure switches:

The air pump and relays are activated by a main toggle switch. Engine boost is controlled using a modified adjustable solenoid valve (stage 3), they are activated by a second toggle switch, because I don't want to reach for the dash under acceleration I carved a hardwood shift knob to install the toggle switch on, because of the shape of the shift knob I made a custom adjustable shift rod that puts the knob at the right position and allows the shifter travel to be adjusted:

I then added a hall sensor to the shift rod and a magnet to the assembly that holds it. To identify 1st gear and activate a second modified solenoid valve when desired.
The water / alcohol system has a tank level sensor and tank pressure switch. If tank level or pressure is low the Stage 3 solenoid valve and shift knob button become inactive.

Everything is controlled and powered by what I call a Central Processing Unit :

The wiring for diagram for the CPU:

#### geekoftheweek

Joined Oct 6, 2013
660
Interesting project.

The reason for the battery is because you are adding voltage to what the O2 sensor is putting out. It's just an easy way to do it. You could use an isolated power converter instead of a battery. Although I don't know how there has to be a way of creating a simple adder circuit to bump the voltage.

It's not so much that your circuit can't be connected to the automotive electrical system as much as it is in this case you are connecting power sources in series. Say at a given moment the O2 sensor generates 0.5V and then the battery circuit adds another 0.2V making the ECU read 0.7V. If you were to tie the battery ground to the vehicle ground it wouldn't work the same way and possibly damage the sensor.

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Joined Nov 8, 2019
29
Use an op amp adder circuit to offset with a buffer on the sensor input. Note that many computers will set the check engine light if the perceived sensor voltage does not regularly go to less than .5 Volts as it cycles the A/F ratio to check sensor operation. I happened to build a circuit for this exact purpose and used it on my new at the time '84 Fiero. Unfortunately I have lost my notes but I found the board and it used a TLC27M4 low voltage precision op amp. A bunch of parts were removed so no circuit diagram!

Joined Nov 8, 2019
29
I used a follower circuit from the sensor into an adder circuit to offset the voltage. Sensor impedance was near infinite cold to about 1 megohm on my narrow band sensor.
Wide band sensors are completely different, see various sources on the web.
To set idle mixture with a narrow band sensor use a DVM and adjust mixture to get 0.5 volts out. This is the max efficiency point on a catalytic converter and got my '90 Bentley with mechanical injection thru an emissions test.

#### Rich.Armitage@gems.co.uk

Joined Jul 17, 2008
1
Interesting project.

The reason for the battery is because you are adding voltage to what the O2 sensor is putting out. It's just an easy way to do it. You could use an isolated power converter instead of a battery. Although I don't know how there has to be a way of creating a simple adder circuit to bump the voltage.

It's not so much that your circuit can't be connected to the automotive electrical system as much as it is in this case you are connecting power sources in series. Say at a given moment the O2 sensor generates 0.5V and then the battery circuit adds another 0.2V making the ECU read 0.7V. If you were to tie the battery ground to the vehicle ground it wouldn't work the same way and possibly damage the sensor.

Joined Nov 8, 2019
29
Sensor is tied to vehicle ground via the exhaust system. Using an adder or summing circuit works well but it is necessary to check that your power supply neutral is within .1-.2 volts of sensor ground or it will definitely confuse the computer re a '90 Bentley with a loose ground connection!

#### MazdaCarnage

Joined Apr 26, 2020
7
Thank you for the replies and suggestions so far. My original post was longer but I couldn't insert any more thumbnail images, the plan was to prepare two post and post them one after the other. I somehow posted the first one early and the second post (this one) got erased. So I will put up the second half of the 1st post than address your replies and suggestion.

None of this is pertinent to the EFIE question but is all part of the project.

Boost stage LED control:
Will the Diode in the diagram prevent the LED after it from flickering or lighting up?

Water / Alcohol boost solenoid and injection solenoids function:

Because of the Air tank and compressor why not ad and air horn:

Engine bay wiring and connector diagram:

I have yet to make a wiring diagram for the dash harness but have listed most of the devices and number of pin wiring connectors for each device, so far not including the EFIE, three timing control potentiometers, two gauges and some other stuff I count 20 devices and 62 wires.
The pinouts for each device are easy.
Listing every wires destination is easy.
Designing a wire harness that everything added on the car plugs into with multi prong automotive connectors one wire at a time isn't that hard.
Visualizing an entire section of harness with every wire in it all at once to mentally design it to function the same but require the least number of connectors and wires is challenging.

As you can see my electronics skills are primitive and I probably over complicate the simplest things but by working with what I understand I can mentally prototype and confirm the function of an idea as I am sure many of you can with circuitry.

If this was the only project being done on the car I would probably devote hundreds of hours into learning electronic components and finding a solution to making a reliable foolproof EFIE controller. But at the same time all this is going in the car the, car is getting a replacement body that is stripped to a bare frame to be painted, rebuilt motor with ported head, many factory suspension replacement and customized parts, a few upgraded parts, the car was already modified from head to toe 5years ago but it all needs to be removed and reinstalled, the fuel controller and timing controller have had the on board 5 pin map sensors replaced for gauge pressure sensors (they take pressure readings above atmospheric pressure) and the outputs have been mapped out, I have a lot of spare parts so anything rusty or questionable gets replaced. All the work except painting and aligning the car is done by me.

This was meant to be a simple body swap but the homemade water /alcohol injection kit functions so well and made the car so much faster I decided that the no budget build deserved a small budget and large amount of effort, it has become a daunting task.

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#### MazdaCarnage

Joined Apr 26, 2020
7
Interesting project.

The reason for the battery is because you are adding voltage to what the O2 sensor is putting out. It's just an easy way to do it. You could use an isolated power converter instead of a battery. Although I don't know how there has to be a way of creating a simple adder circuit to bump the voltage.

It's not so much that your circuit can't be connected to the automotive electrical system as much as it is in this case you are connecting power sources in series. Say at a given moment the O2 sensor generates 0.5V and then the battery circuit adds another 0.2V making the ECU read 0.7V. If you were to tie the battery ground to the vehicle ground it wouldn't work the same way and possibly damage the sensor.
The Narrow band O2 sensor can hold up to temperatures hot enough to turn cast iron red and see through, sits in the front of the engine bay and gets blasted with water and salt all winter and lasts up to and above 20years on this type of car. Physically the O2 sensor is very durable but electrically the O2 sensor is very delicate, I have seen them short from simple bench test with a multimeter.

This combined with my limited knowledge of electronic components and their function prevents me from formulating a fool proof design in my head, putting it on paper, researching it, refining it and finally fabricating it. I could of course bench test using two mutimeters and no sensor, one multimeter to read the output voltage of the EFIE in place of the ECU and sensor and a second to test for continuity between the car body ground and the EFIE.
Fear of doing all this, installing it on the car and shorting the O2 sensor is holding me back.

Replace the battery with an isolated DC-DC converter, adjust the resistor to match accordingly. One of https://www.electronicsurplus.com/fil-mag-80z1209unh-dc-dc-converter-12vdc-input-to-9vdc-output might do with the input given adequate protection from vehicle transients.
I looked at DC-DC converters last year, inspired by the ac-dc 24V converters used in building controls systems, they have a board mounted pot sensor so DC voltage output can be dialed in accurately. But like your links URL shows "12vdc in to 9vdc out" I couldn't find anything that brought me close to the 1.5V output of an AA battery or lower.
Do fluctuations in the input voltage affect the output voltage of a voltage converter? The vehicles electrical system voltage can be as high as 13.7V and (on my 2door version of this car running an underdrive utility pulley to drive the alternator) as low as 11.4V .
The 2 door was running an old school wideband device that displayed voltage, I have no vehicle voltage display on this car.

Use an op amp adder circuit to offset with a buffer on the sensor input. Note that many computers will set the check engine light if the perceived sensor voltage does not regularly go to less than .5 Volts as it cycles the A/F ratio to check sensor operation. I happened to build a circuit for this exact purpose and used it on my new at the time '84 Fiero. Unfortunately I have lost my notes but I found the board and it used a TLC27M4 low voltage precision op amp. A bunch of parts were removed so no circuit diagram!
Note to self: Look up Op amp adder circuit and buffer. "On the sensor input", stupid question since there is only one wire but you mean the signal wire from O2 to ECU, before or after the Op amp?
As for the check engine light It should be okay, the car is from 1988 and pretty low tech, in the old body (the car currently sits in) something might be shorting to ground, all potential causes are being addressed on the new body. A few months after it's final engine modifications and primitive tuning it started running rich under normal driving but threw no codes, I made the EFIE controller and that helped but I couldn't adjust the initial idle A/F ratio on the car after it started running rich with or without the EFIE.
This car has a single wire ground to frame test connector used to read codes, adjust timing, adjust idle and idle A/F's the ECU stops auto adjusting to match signal values and can be set to chase new ones. The car uses a vane air flow meter, it has a chamber on the side that allows idle air to go around the flap in the meter, the amount of idle air is adjusted by a screw, by grounding the test connector and adjusting this screw the idle A/F's change and once the test connector is disconnected the ECU chases that voltage output from the O2 sensor at idle. Because idle A/F's can't be changed the only 2 suspects are some part of a 12V signal is trickling to ground or there is an air leak in the intake system, I have pressure tested the intake system but found no major leaks.

The innovate wideband the car runs has a simulated narrow-band o2 signal and it has replaced the factory o2 signal to the ECU. But that will change on the new body.

I used a follower circuit from the sensor into an adder circuit to offset the voltage. Sensor impedance was near infinite cold to about 1 megohm on my narrow band sensor.
Wide band sensors are completely different, see various sources on the web.
To set idle mixture with a narrow band sensor use a DVM and adjust mixture to get 0.5 volts out. This is the max efficiency point on a catalytic converter and got my '90 Bentley with mechanical injection thru an emissions test.
More to look into.
I live in Quebec Canada we don't have emissions but running proper A/F's is a goal.

The car runs a factory ECU with "boost cut" removed (boost cut = the ecu reacts to the voltage returned by the Vane flow meter, if the vane/flap travels too far the injectors shut down). The factory ECU is set-up to run 87 octane fuel but I run 94 octane fuel due to modifications.
Higher octane fuel contains less energy than lower octane fuel so more is required to generate the same power output however due to it's increased knock suppression regular driving A/F's can be leaner than on low octane fuel.
The factory ECU goes into Open loop at and above 3000rpm no longer using the O2 sensor signal.
The factory injectors are 325-360cc each and batch fired 2X2. The car has a high volume high pressure fuel pump and adjustable rising rate fuel pressure regulator which is used lowers fuel rail pressure when it's pneumatic reference is below atmosphere (in vacuum) at atmosphere fuel pressure is 40psi (factory) and rises at a 1:1 psi rate (factory). This lower base fuel rail pressure helps with the gas millage during regular driving above 3000rpm.
The factory injectors can supply enough gas to manage 15 psi boost at safe air fuel ratio's.
Above 15psi a Simple Digital Systems Extra Injector Controller operates two batch fired 650 cc injectors. This controller used a 2.5bar Map sensor and had an adjustable start point from -10 InHg to 22 psi, above 22psi = 100% duty cycle it now has a 2.5bar gauge pressure sensor 0 -36 psi, because both sensors have the same resolution (2.5 bar) and voltage signal (0 to 5v dc), the replacement sensor will not affect the operation of the controller just increases the pressure range. The controller also uses ignition coil pulse signal to control it's fuel delivery map and has a gain dial allowing to dial in fuel delivery from 10 to100% duty cycle.

Areas and types of fuel control

Idle - 800rpm. Air/fuel ratios are controllable.
800-3000rpm. Fixed factory maps. Requires EFIE for fuel control.
3000 + rpm. Fuel pressure regulator adjustable A/F's
@ 15psi Factory injectors run at fixed duty cycle. A/F's have changed with a higher flowing turbo, charge pipes, throttle body, intake manifold and head (increased volume at the same pressure), from stock factory 10.5-10.8 A/F's @ 15psi on 87octane to 11.8 A/F's @ 15psi on 94 octane, the larger turbo generates less heat than factory and requires less additional fuel to cool the charge air which is good because higher octane fuel is lighter and thinner and requires using a lot more to equal the cooling effects of lower octane fuel.
15psi to 22psi. A/F's are adjustable with the injector controller.
22 to 30psi. The injector controller continues it's map and water/methanol 51/49% is injected, the old set up used two solenoids, two stages and 6 misting nozzles, at 30 psi engine boost (minimum boost required to match full extra injector duty cycle) the liquid pressure regulator had to be set at 66psi. The new set up has 3 solenoids, 3 stages and 7 misting nozzles. The set point of each stage and delivery will require fine tuning. With the Extra injector controller set to deliver fuel to maintain ratios 11.8 to 11.3 air fuel from 15 to 30 psi the water methanol injection needs to be staged and sized to maintain 10.8 to 10.3 air fuel ratios from 22 to 30 psi.

The EFIE controller (800-3000rpm) would seem least important when it comes to making a car fast, but the unfortunate reality is the engine spends much of it's time in the closed loop O2 rpm range which makes the EFIE most important. Because the ECU goes to open loop fuel control above 3000 rpm the EFIE has no effect on air fuel ratio's under boost/ heavy engine load, this means in a worst case scenario if the EFIE fails and fries the O2 sensor this cannot contribute to engine predetonation causing critical engine failure.

The current (old set-up) MPG is about 15.3mpg average, getting above 18mpg average is one of my goals on the new set-up.

#### geekoftheweek

Joined Oct 6, 2013
660
I won't argue the delicate electronics of the O2 sensors, but at the same time they aren't a typical variable resistance sensor as most automotive sensors are either. It can be done. What kind of bench test was it that damaged the sensor? They may not like a resistance or continuity test, but reading the voltage output while running shouldn't be a problem unless you're using a really cheap meter or analog gauge type meter.

As mentioned above check out op amp circuits. Connecting the O2 sensor to an op amp buffer will more or less separate the sensor from whatever else happens after the op amp. Follow the buffer op amp with a summing op amp circuit and feed that into the ECU. In the end it won't be as simple as it sounds, but more or less somewhere to start.

#### MazdaCarnage

Joined Apr 26, 2020
7
Summing Amplifier - Op amp.
I had not even thought about how to add the two voltages into one. Even though I know the battery adds voltage because it's in series and that adding two dc voltages in parallel does not increase voltage only amperage.

This is the what I am picturing as a setup:
12V ignition ---------Voltage reduction--XX---Potentiometer controlling------------------------------------Summing---------- ECU
switched signal . . . From 12v to 0.2V . . . . . 0v to 0.2v output ] . [ Isolated O2 signal ---------------Amplifier

XX is what I'm missing, a way to Isolate the automotive electrical power source from the vehicles ground or is this not necessary?
Realistically despite the fact the O2 sensor generates it's own 1v current it is grounded to the car's body, therefore the ecu is using the electrical systems ground to pick up the O2 sensors positive voltage.
But does the ECU require the positive voltage signal to be isolated from the cars 12V + electrical system?
Is the Innovate Motorsport Wideband simulated narrowband signal isolated?
So simply isolating the O2 sensors output signal from having any other voltage return to the O2 sensor would protect the sensor.

I have been following this premise:
_____________________________________________________________________________________________

"I really am puzzled at people who put information on the internet that is missing critical details, missing
necessary steps, missing diagram labels, or worse, diagrams that are just plain WRONG or even worse
such as the videos that DMBing put on youtube, videos that tell people to do things that will blow up
their electronics, or short things out, or damage equipment! DMBing put out a video showing how you
just grab any old cigarette plug-in ADAPTER, that typically takes IN the +12 Volts and puts out anywhere
from +3 Volts to + 9 Volts.... He states that you can use this replace the batteries in the Simple Cheap
EFIE, since it can give you power from the car itself. When I saw the Video I was horrified, since I have
have worked with thousands of different adapters, and the typical CAR, (+12 Volt Power IN ) types
over the past 20 years, all SHORT TO GROUND ! I have seen ONE, and only ONE cigarette lighter
adapter that had a complete switch mode power supply transformer, to ISOLATE the Output from
ground! ONE..... ( 1 ). When I mentioned this to my friend who is very handy with things, he said -
well that's easy - just use a cigarette lighter to USB output- they are isolated.... WELL, ...NOT...;I
don't have dozens of the OLD USB adapters, and I suspect a really expensive, BIG, OLD, one may
include a switch mode power supply, and a big ISOLATION TRANSFORMER, but the COST of
the copper used alone would make this a very high-end device. So ....
Gathering a few power adapters I had lying around the house,I took out a sampling of typical +12 Volt Cigarette Lighter Power Adapters, and tore them apart to see what electronic circuits were used on the inside. NONE had an isolation transformer, just
as I expected....
DMBing is leading everyone down the path to frustration, and possible damage to
the computer electronics...

MOST CERTAINLY, the Oxygen sensor will NOT WORK if it is
shorted to GROUND, which every single adapter I have used in recent years, WILL DO !
DANGER ! WARNING ! I am not certain what DMBing's motive is, in putting out information that
"appears" like it is "working" in "HIS" vehicles, but will KILL your engine's computer, if you try to
copy him....

The next test was to get typical USB adapters designed for +12 Volt Cigarette Lighter Sockets,
and see what circuits was commonly used... Again, ripping them apart, I could see clearly that
that the OUTPUT was shorted directly to GROUND! NADA. NOPE. ZILCH... SORRY, but
unless you have a RARE, OLD, BIG, HEAVY adapter that costs $125 U.S., don't even think about it! You WILL just KILL the Oxygen Sensor output, and your engine's computer, seeing a dead short, will go into permanent "LIMP MODE" default, and you will experience terrible engine performance." __________________________________________________________________________________________________ #### shortbus Joined Sep 30, 2009 8,690 You keep using the term EFIE, so unless that means something else that I'm not aware of, you are trying to add HHO to your intake stream? You do know while a motor will run on hydrogen it doesn't help much at normal gasoline compression ratios. And on board hydrolysis can't make enough hydrogen to make much of a difference anyway. And by adding/raising the voltage on the O2 sensor aren't you telling the ECM that the engine is running rich and to cut fuel? Isn't a low voltage the signal that the motor is too rich? Last edited: Thread Starter #### MazdaCarnage Joined Apr 26, 2020 7 You keep using the term EFIE, so unless that means something else that I'm not aware of, you are trying to add HHO to your intake stream? You do know while a motor will run on hydrogen it doesn't help much at normal gasoline compression ratios. And on board hydrolysis can't make enough hydrogen to make much of a difference anyway. And by adding/raising the voltage on the O2 sensor aren't you telling the ECM that the engine is running rich and to cut fuel? Isn't a low voltage the signal that the motor is too rich? Electronic Fuel Injection Enhancer. (Which I spelled wrong in the tittle). A device that's adds voltage to an O2 sensor signal at the ECU isn't exclusive to running HHO or Hydrogen in a motor. No I am not running Hydrogen. I am running water and methalhydrate but that's not what the EFIE is for. I'm not one of those people, personally I believe if you don't have a smile from ear to ear when you drive your car every penny spent on fuel is wasted no mater how economical or fuel efficient the car is. Carbon footprint rant- Everything new should come with a tag, displaying the carbon pollution created by recycling and manufacturing the product, the guy who leased new hybrids and then every new model of electric car wouldn't think he's such an environmentalist anymore. What are normal gasoline compression ratio's between 7.2:1 and skyactive X 16.3:1? This motor is factory 7.8:1 compression and I port the combustion chambers in the head to get that down to 7.5:1 or 7.4:1 compression ratio allowing me to run 30psi boost on factory pistons, rods, cam and timing. Yes by adding/raising voltage on the O2 sensor the ECU will think the engine air fuel mixture is rich and cut back fuel. If by adding voltage the ECU cut fuel than high voltage is the signal the motor is running rich otherwise my EFIE would require nothing more than a potentiometer to reduce the voltage going to the ECU and I wouldn't have posted this thread. #### Leadfootin Joined Nov 8, 2019 29 I suggest you look at using a wideband with analog output then you can tailor a modification circuit to your target a/f ratio instead of being restricted to the 14.0:1 up to 15.0:1 of the narrow band sensor you are using. Look up Innovate.com for an example. I think an LCII may be what will work. #### shortbus Joined Sep 30, 2009 8,690 allowing me to run 30psi boost on factory pistons, rods, cam and timing. Yes by adding/raising voltage on the O2 sensor the ECU will think the engine air fuel mixture is rich and cut back fuel. I take it this isn't a road car? You are flying in the face of all that are doing this type of thing, meaning power adders in engines. Wish you well but hope you have money to keep it running. Thread Starter #### MazdaCarnage Joined Apr 26, 2020 7 I suggest you look at using a wideband with analog output then you can tailor a modification circuit to your target a/f ratio instead of being restricted to the 14.0:1 up to 15.0:1 of the narrow band sensor you are using. Look up Innovate.com for an example. I think an LCII may be what will work. The old version of the car is currently running the analog output of an Innovate LC1 as it's ECU O2 sensor signal. I wanted to work out the kinks in the system and go back to running the factory narrow band O2 sensor to the ECU because the gas millage was better than with the analog signal from the wideband. I am sure the wideband signal is more accurate than the narrow band sensors signal but I believe the sensors position has something to do with it. The narrow band sensor sits in the direct path of the turbos turbine 3" from the blades (Point A), the wideband sits just over 24" after the turbo (Point B). Running the engine off a signal from Point A and taking independent gauge readings from Point B wasn't an issue because I can only tune A/F in opened loop O2 ecu positions (heavy throttle or above 3000rpm...) it didn't matter what point A reports to the ECU, because I only see and tune by point B readings. With the ECU getting its readings from point B 24+ inches from the turbo it seems to get a leaner reading from the exhaust and the car runs a little richer. The LC1 analog 1 output is factory set to 1.1V = 14 A/F and 0.1V = 15 A/F. I was so hell bent on getting the car running properly on the factory narrowband sensor again that I never though past that point. You are a genius, the LC1 is programmable I reprogrammed analog output 2 0-5v on my 1989 2 door turbo model of this car to run as one of the fail safes for the Aquamist Hydramist electronic programmable water meth system on the car. It won't even need a modification circuit because the programmable analog 1 output on the LC1 I can completely remap the A/F's of the 0.1 V to 1.1V signal to represent A/F ratio anywhere between 7.40 and 22.10 A/F ratio's 1.1v = 14.5 A/F's and 0.1V = 15.5 A/F's would be a starting point, then I can expand or reduce the A/F range and increase or decrease the resolution to dial in the perfect cruising A/F ratios, perhaps a range of 1.50 A/F would work better than 1.00 A/F or maybe it's 0.75 A/F range? Also the response speed of the signal to A/F changes can be changed to get the smoothest average A/F ratios. Thank you Leadfootin you found the solution to controlling all cruising and Idle Air / Fuel ratio's on my car. Ironically it is on my car already and driving the ECU o2 signal and all my efforts where to disconnect it from the ECU. And I knew it was programmable. My rationalizing to why I was so stupid and blind is that using LC1 analog out 1 was a temporary solution to the O2 sensor issue the car was having and the only thing on my mind was returning it to the factory sensor and controlling it's signal, I got so caught up in the idea of dial controlled cruising A/F ratios that I even pondered using the EFIE controller on the LC1 signal if there is no chance it could damage the LC1 like it could the Narrowband sensor. Not once did I think of simply reprogramming the analog signal of the LC1. I will be honest there is a part of me that is disappointed I wont be running an A/F control dial to go with the MSD base timing dial, MSD degree timing pulled per psi dial, the MSD psi start point dial, the SDS fuel psi dial and the gain dial. But that's the part of me that's stupid, he will get over it and forget all about it in no time. The logical part of me is very happy to already have everything I need for more reliable and more flexible "unlimited" fuel control between 800-3000 rpm than an EFIE could ever provide with far less fail points. And the fact the Narrow band o2 sensor will be removed from the exhaust means slightly better flow. You are awesome. #### Leadfootin Joined Nov 8, 2019 29 Thanks MazdaCarnage! Been tuning for 50+ (oh sh_t I am old) years! Watch out for the MSD boxes going bad. Had a bit of spark scatter with an MSD 7AL which eventually became serious due to a failing SCR. Took out a set of rings and pistons - ring land damage. Back in the '70's building my own CD boxes SCR failure was fairly common both due to peak current and mostly from DV/DT and no effective back diode. Now I would use a SIC FET with proper driver. The best MSD box was a 404B, try finding one, though the 7A unmodified is fairly good. Also note the timing issues with any mag pickup distributor pulling advance as the revs increase. I have seriously considered a Megasquirt 3 but don't have anywhere I can load the engine for more than a few seconds making tuning a bit difficult. Main playtoy is a Morgan +8, ex road racer, never ever stock! Replaced Rover 3500 with a very healthy iron 350 Chev. Current iteration is 406 cid, alum block SBC. Lighter than original engine with modded turbo 350 trans. Putting 650 hp to the ground is fun. Per distributor, I am currently using a POINT dist from a Penske IROC Camaro race car, with a hazy historydue to source and extreme accuracy. 30 degrees advance plus 9 degrees vacuum starting at 10". FWIW engine is ultralight internals, 13:1, good for 9500, Peak at hp at 8000 torque at about 6500 making good use of 4500 converter. Those Yoko A048's can be temp sensitive but do handle and hook well. FWIW I switched diff to an Eaton helical diff and made a huge improvement on turn in and straight line traction. Thread Starter #### MazdaCarnage Joined Apr 26, 2020 7 I take it this isn't a road car? You are flying in the face of all that are doing this type of thing, meaning power adders in engines. Wish you well but hope you have money to keep it running. This is a road car, in fact it's a daily driver. "all that" has been running reliably for years. This engine is turbo charged from factory, I simply increased the size of the turbo and items that support better flow and more boost. For under 3000$ including the car cost and about 2500\$ worth of parts I already had, the engine and transmission suspension and brakes can handle 30psi boost reliably.
My goal on the new body is to increase handling, braking, tuning, gas millage and run more conservative timing and sacrifice some power for added reliability.