An O2 sensor calibrator using a pressure switch

[mastacox]

Edit- I went ahead and changed the title to what this thread turned into- a build of my own O2 sensor calibrator setup :smokin:

Well my factory oxygen sensor's on the fritz, and while I'll be down in the ECU wiring replacing it with a simulated output from my wideband sensor, I'm wondering if I can fix my oxygen sensor bypass issue that plagues so many people with FI and a URD kit...

http://www.urdusa.com/images/O2Cal500.jpg
URD O2 Sensor Calibrator (http://www.urdusa.com/product_info.php?cPath=66_72&products_id=1260518747)

So URD finally has something that might work, but I want to hear if anyone has actually bought the thing, since at $265 it ain't cheap. The ESC1 is notorious for not working in this application (the same circuitry is apparently in my FTC1-E, since it doesn't work all that great either), and URD is saying the ESC1 is frequency-based rather than voltage-based like the new one.

So, does it work? Anyone know? Any cheaper off the shelf options for sending a precision 0-1V signal to my ECU based on the input from an MAP sensor?

[Okie81]

Not a bad idea. I don't hear of many people running ESC1 anymore, I'm not sure why.

Are your AFR readings off or are you getting a CEL?

[mastacox]

Not a bad idea. I don't hear of many people running ESC1 anymore, I'm not sure why.

In short, it's because the ESC1 doesn't work :shake: I'm not exactly sure why, but it freaks the ECU out big time when activated making it run super rich (it might be triggering some kind of limp mode). I've been struggling with my FTC1-E, which utilizes similar hardware and has the same problematic symptoms the ESC1 has.



Are your AFR readings off or are you getting a CEL?

I just did a free-air calibration on the wideband sensor, so it's correct AFAIK. I just got a CEL yesterday, haven't checked the code but I'd bet its something to do with the O2 sensor.

Happily, after asking a question on the Innovate! Motorsports website, I have come up with a solution I think will work geniusly!!! My wideband setup is the Innovate! LC-1 (http://www.innovatemotorsports.com/products/lc1.php)/XD-16 (http://www.innovatemotorsports.com/products/xd16.php) combo, and it turns out this will be my saving grace. The wideband controller (LC-1) has two programmable analog outputs that can be used to simulate a narrow-band O2 sensor signal, and a trick some guys have done is to use these two outputs in addition to a SPDT relay and switch. By making one analog output simlate a standard O2 sensor, and the other one with an offset to make 12.0:1 look like 14.7:1 to the computer, you can flip a switch and make the engine run at 12:1 while thinking its at 14.7:1...

So I wanted to take this a step further and make the process automated based on boost, so I went looking for a pressure switch. After searching for 20 minutes or so, I've found a pressure switch I will use in addition to the two outputs on the LC-1:

https://www.dwyer-inst.com/images/Medium/1800_pic.jpg
Dwyer Instruments 1800-series SPDT adjustable pressure switch (https://www.dwyer-inst.com/Products/Product.cfm?Group_ID=32&Product_ID=102&sPageName=Specs)

Dwyer Part Number: 1823-80
Description: Differential pressure switch, range 9-85" w.c., approx. deadband @ min. set point 1.30, approx. deadband @ max. set point 3.0.

The one I bought has an adjustable setpoint of 9-85 inH2O (0.3-3 psi), Operating temperature range from -30F - 180F (perfect for automotive applications), and cost $56. I will integrate this pressure switch with the two analog ouputs on my LC-1 to achieve normal operation in vacuum, and once I hit 1psi the switch will change and give me operation at 12:1. :wrenchin: :wrenchin:

This is going to save me a lot of money and headache, and about $210 too since I already have all of the expensive electronics I need. Thank you Innovate!!!

[Okie81]

Sounds like a good alternative to the URD setup, that pressure switch is trick! The powerband area where you're part throttle under positive pressure can be finicky. It took some mapping modifications to iron out my issues fortunately. I've never heard of Innovative, I'll have to check them out.

[mastacox]

Sounds like a good alternative to the URD setup, that pressure switch is trick! The powerband area where you're part throttle under positive pressure can be finicky. It took some mapping modifications to iron out my issues fortunately. I've never heard of Innovative, I'll have to check them out.


Innovate! (http://www.innovatemotorsports.com/) makes some very cool stuff. Some of the stuff can get pretty expensive, but it can be worth it if you need on-board logging or heavy data collection.

The really awesome part of this setup will be that the stock ECU will acatully be tricked into achieving closed-loop operation on an AFR other than 14.7:1, which means I can just program the analog output on the gauge LC-1 and the ECU will adjust its fuel trims to achieve it. Rather than mucking with the fuel map in the FTC every 3-6 months, I can actually make the ECU work FOR me again instead of AGAINST me.

[MTL_4runner]

Pretty trick setup if that all works.
It will be great to see what results you come up with Brian.

[Erich_870]

I've never really grasped the technical side of engine/fuel management, so I've muddled my way through this thread, but I commend you for finding a pressure sensor that meets your specifications and I look forward to hearing more on this project. :thumbup:

In the interest of learning more about this subject, could you recommend any additional reading about projects similar to yours?

Erich

[mastacox]

In the interest of learning more about this subject, could you recommend any additional reading about projects similar to yours?


I would highly recommend reading the wiki pages I wrote on the supercharger, FTC's, and oxygen sensor calibrators for a better technical understanding of the issues and challenges.

Supercharger wiki: http://www.ultimateyota.com/index.php?option=com_openwiki&Itemid=60&id=wiki:trd_3.4l_supercharger

FTC's: http://www.ultimateyota.com/index.php?option=com_openwiki&Itemid=60&id=wiki:piggyback_fuel_timing_calibrators

Oxygen sensor calibrators: http://www.ultimateyota.com/index.php?option=com_openwiki&Itemid=60&id=wiki:oxygen_sensor_calibrators

[mastacox]

I got the Pressure switch in, here are some pictures of what I'm working with. I'm planning on mounting it in the dash near the glove box, but if it ends up being too big (which it might) I'm going to seal it up with silicone and mount it in the engine bay near the ABS stuff.

The pressure switch. It's obviously bigger than you would find on something like a compressed air system because it works with much lower pressures and therefore needs a bigger diaphragm. I attached the plastic (nylon?) nipple to it for attaching to the pressure line from the S/C. The switch has 1/8" NPT holes for this purpose, one for the low pressure side (atmosphere for me) and one for the high pressure side (boost).
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8404.jpg

The inside of the switch. It's just a basic SPDT switch hookup essentially.
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8407.jpg

The switch. "Common" will be wired to the ECU in place of the factory O2 sensor's signal, "Normally Closed" will be a standard narrow band oxygen sensor input from the LC-1, and "Normally Open" will be an offset signal input from the LC-1 which makes 12:1 AFR look like 14.7:1.
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8408.jpg

The pressure manifold for the engine bay I pieced together quickly. The boost port on the S/C has to be piped to 4 things: 1) Fuel Pressure Regulator, 2) FTC1-E, 3) Boost Gauge, and 4) My pressure switch for the oxygen sensor signal clamp.
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8406.jpg

I'll be leaving the factory O2 sensor in place with the heater wire connected, because otherwise the ECU will throw a CEL (oxygen sensor heater circuit something...). So the ECU will be heating the factory sensor and think it's getting readings from it, when in fact it's getting them from a more advanced system.

[Okie81]

Nicely done, have you given it a test spin? I'm curious how smooth it transisitons from closed/open loop. That pressure manifold setup is pretty trick too, I may have to do something like that as well.

[mastacox]

I haven't finished installing it yet. My dash is apart and I've been trying to clean up some of the wiring back there from the FTC, aftermarket gauges, and extra lighter plugs.

I still haven't found a good place to put the switch due to its size, I'm considered putting it under the passenger seat but I don't want the air line going to it to be too long because it will degrade response time (plus it would kind of be a PITA). Dwyer has a weatherproof housing for the switch that I considered buying, but it was heavy and more expensive so I opted out.

Decisions, decisions. :headscratch:

[mastacox]

Well the results are in: IT WORKS :lol:

I haven't put the dash completely back together yet, and I haven't mounted the switch so it's just sitting on the passenger side floor, but I drove around and it actually works just like I hoped it would! I programmed the LC-1 so that the two analog outputs are programmed around 14.7:1, and about 11.7:1, and when I push into boost the AFR drops from 14.7:1 to about 12:1!!! No check engine lights, no strange hesitation, just a smooth power increase as the AFR drops :love:

I spent most of my time neatening the wiring of all of my various accessories (especially the FTC). Here are some pictures so you believe that I actually did something :hillbill:

The dash torn apart. I wanted to check to make sure the FTC was still firmly held in place, and I needed access to the wiring going around back there to add some zip ties and neaten things up.
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8409.jpg

The FTC, still wedged in the same spot, wrapped in blue masking tape to insulate it.
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8412.jpg

Here is what I was working with behind the glove box. When I installed the FTC 4 years ago I was worried about getting the thing running, not trying to make it pretty.
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8413.jpg

Well I went wild with some zip-ties and here is the result. It's at least marginally presentable now. The two very thin wires hanging in the middle of the picture are the two analog outputs from the LC-1, I extended them and hooked them up to the pressure switch along with the extra pressure line I brought through the firewall.
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8415.jpg

[mastacox]

I have only one unexpected side effect- the pressure switch whistles a tiny bit when I first push the engine into boost. It's from the air rushing into the body and pushing the diaphragm.

I can live with it as long as the engine runs like its supposed to ;)

[DHC6twinotter]

This is really cool. Some of it is over my head, and I wish I had the brains to figure all this out. From what I'm understanding, it sounds like an ingenious solution. :hillbill:

[mastacox]

This is really cool. Some of it is over my head, and I wish I had the brains to figure all this out. From what I'm understanding, it sounds like an ingenious solution. :hillbill:


Thanks! I'm glad I can help keep your brain on its toes :D

[MTL_4runner]

From what I'm understanding, it sounds like an ingenious solution.

It is!

Very well done Brian, I'm impressed. You should post a Youtube video with it going back and forth between open and closed loop so we can all see what the transition is like in real time.

[Okie81]

Good god man, Seeing that mass of dismantled dash and wiring sent a chill down my spine! I didn't see a picture of the pressue switch, but I assume you decided to install it inside the cab since you can hear it.

[mastacox]

Very well done Brian, I'm impressed. You should post a Youtube video with it going back and forth between open and closed loop so we can all see what the transition is like in real time.


Thanks MTL. Remember- the setup means the ECU never actually transitions to open loop (unless I floor it). Instead, the ECU is functioning in closed-loop mode, but I send it an offset O2 sensor signal so I thinks the AFR is higher than it really is. In this way, I can just offset the signal from the LC-1 in any direction I like, and the ECU achieves it through closed-loop operation! Rather than trying to prematurely trigger open-loop operation, I'm doing one better and setting an AFR point other than stoich that the ECU will try to achieve :thumbup:



Good god man, Seeing that mass of dismantled dash and wiring sent a chill down my spine! I didn't see a picture of the pressue switch, but I assume you decided to install it inside the cab since you can hear it.


Haha, oh that's not all that bad; it's basically what you need to do to install the FTC and oxygen sensor gauge. Check out the attached pictures from me hunting down a cig lighter wiring short in my old 1992 4Runner!!!

You're right that I decided to install the pressure switch in the cab. I'm going to be zip-tying it in the passenger footwell as far under the dash as possible.

[mastacox]

You should post a Youtube video with it going back and forth between open and closed loop so we can all see what the transition is like in real time.


By the way MTL, I'm planning to do this some time this weekend, I'll post it up when I do it.

[MTL_4runner]

Thanks MTL. Remember- the setup means the ECU never actually transitions to open loop (unless I floor it). Instead, the ECU is functioning in closed-loop mode, but I send it an offset O2 sensor signal so I thinks the AFR is higher than it really is. In this way, I can just offset the signal from the LC-1 in any direction I like, and the ECU achieves it through closed-loop operation! Rather than trying to prematurely trigger open-loop operation, I'm doing one better and setting an AFR point other than stoich that the ECU will try to achieve :thumbup:


Sorry, meant to say transitioning between AFR's not open/closed loop.
Good job on it all nonetheless!

[mastacox]

So I figured I'd post a small update...

I finished mounting the pressure switch in the passenger footwell. It doesn't infringe on foot space any more than the heater core and blower fan, so I'm ok with its location. It has one pressure tube and 3 wires that go to it, so I zip-tired them all together and shoved them up under the glove box too.

http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8441.jpg
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8442.jpg
http://i93.photobucket.com/albums/l70/mastacox/Pressure%20Switched%20Fuel/IMG_8443.jpg

Overall I'm very happy with how the 4Runner has been running, pickup and throttle response have increased dramatically in low vacuum and boost.

... although I think this oxygen sensor may be fouled as well. It will go through little tantrums after running rich for a while where it says the AFR is 30 or 40:1 (obviously wrong wince it quickly changes between the real AFR and the wrong one, with no change in how the engine is running). Happily, when the AFR displays lean like this, the engine tries to compensate by turning up the fuel trims, so at least it's running safely (albeit too rich).

So I'm replacing this O2 sensor too, fortunately it's cheaper than the Toyota OEM sensor, about $75. I guess whatever fouled my factory sensor fouled this one too (could have been all that burning coolant a few months ago before I rebuilt my engine). I'm looking forward to getting the new sensor and seeing how this system really works, but even now with a finicky sensor I have much better power than before.

[Okie81]

That vaccum switch looks a lot bigger than in the previous pictures, but it mounts up there very nicely.
I'm pretty sure an over-oiled K&N filter caused my factory O2 sensor to get screwy. Like you mentioned, a finicky 02 sensor can make tunining difficult, especially when you're trying to dial in you AFR and its bouncing around.

[mastacox]

I'm waking up this thread for a bit of an update. :wrenchin:

Overall my little oxygen sensor setup has worked pretty well over the past 3 years or so. It's not perfect, but it does OK.

The pressure switch has lasted for almost 3 years of daily use, but now its preformance has degraded to the point where the "set point" is at less than 1 psi and can't go any higher, so I'm going to replace it with a new one:

https://www.dwyer-inst.com/images/Medium/A6_pic.jpg
https://www.dwyer-inst.com/products/product.cfm?Group_ID=671

It's a much smaller switch with similar characteristics, although its set point range is higher. I've pretty much decided that you want the set point for such a setup to be higher than 3 psi to minimize actuations during normal driving. You don't really need the fuel mixture to richen until the boost starts to build unsafe compressor discharge temps, and those probably don't start happening until more than 3 psi. So, in an effort to minimize check engine lights, we're going to go to a 5 psi switch pressure for a while and see how things go. I think some of my problems may be alleviated with a better tune of my FTC (mainly fuel in the idle area), so I'll have to mess around with that.

There's a sort of fundamental problem with the setup in that switching from "normal" O2 sensor operation to "offset" operation causes a discontinuity in the ECU's fuel trim map (basically it instantly has to change from a fuel trim of zero to +20 with no gradual increase in between). I think this could be one of the reasons behind the check engine lights, but I'm not sure what the best way is to combat it. The switch is relative rather than absolute, so its actuation point changes in the absolute sense depending on my location; I looked into replacing it with an "absolute pressure switch" to give it a set actuation point regardless of ambient pressure but the ones I've found thus far are pretty expensive.