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  Topic Review (Newest First)
05-15-2019 05:29 PM
Hodgdon Extreme
Quote:
Originally Posted by Alex_MP95 View Post
My question exactly. The computers in cars have gotten incredibly sophisticated and in some ways the Lexus ECUs were ahead of the curve from what I understand. And it seems many on the forums have the same sentiments. Like I said, some people seem to have zero issues with a sim, and others can't go 5 miles without a MIL. If there is a sim that can accurately and consistently fool the ECU, then I'd be more than happy to take a look at it. But it seems most are a crap shoot at best.
As I kinda mentioned before, referencing the dude on clublexus trying to get his diagnostic monitors to work...

I don't see why the OEM ecu can't be satisfied, provided the catalysts and O2 sensors are in place and functioning.

I think the key to it may be getting the medium load fueling correct. No monitors run during WOT, so no worries about the fat mixture during heavy acceleration. However, during light and medium load, the mixture MUST switch lean/rich/lean. If you calibrate the engine to run dead steady from a linear-output wideband, the OEM narrowband sensors are going to "stick rich", "stick lean", or have "slow response" (because the slope of the lean/rich switch isn't steep enough and they're not constantly passing thru the .55V stoich point), which will not satisfy the upstream O2 monitor (reference my last post) or the operational needs of the catalyst, which will in turn not satisfy the downstream O2 sensor monitors.

I wonder if anybody has tried this with a good programmable ecu with NARROWBAND closed loop feedback?

The ecu might additionally need calibrateable gain on the PID algorithm driving the closed loop (to get amplitude and frequency of the waveform right). Hell, now that I think about it, calibrateable PID of wideband closed loop oughta be able to achieve this, but the non-linear characteristic of a narrowband might achieve it naturally.

Also, part of the DSO2 monitor strategy relies on proper response to a DCFC... So getting the fuel cut calibrated correctly would also be a requirement.
05-15-2019 05:01 PM
Alex_MP95
Quote:
Originally Posted by Hodgdon Extreme View Post
Quote:
Originally Posted by Lexyaaaas View Post
The ecu doesnt care about the rich/lean on the downstream. Only the upstream. You can leave the OE O2s for the with the car in the exhaust system upstream (and add additional O2s for your standalone). But then when you tune, your stock ecu is going to freak out about the variation from the stock parameters.

You only want an O2 sim is only after the cat. Entire idea of the O2 sim is to make the ecu think theres a cat there still. You dont want a cat because cat on a turbo car is like exhaling through a straw.
So basically:

1. If the DSO2 switches kinda like the upstreams, it means the catalyst isn't having any effect on the exhaust, so therefore the catalyst is most definitely bad.
2. The DSO2 should read full-tilt lean for seconds at a time, else the catalyst's "oxygen storage capacity" is in question.
3. During decel fuel cut, the DSO2 needs to immediately recognize the change in fueling. This is part of the diagnostic of the sensor itself, not the catalyst.

Are the "O2 sims" smart enough to massage the signals all the time to satisfy the ecu?
My question exactly. The computers in cars have gotten incredibly sophisticated and in some ways the Lexus ECUs were ahead of the curve from what I understand. And it seems many on the forums have the same sentiments. Like I said, some people seem to have zero issues with a sim, and others can't go 5 miles without a MIL. If there is a sim that can accurately and consistently fool the ECU, then I'd be more than happy to take a look at it. But it seems most are a crap shoot at best.
05-15-2019 11:37 AM
Hodgdon Extreme
Quote:
Originally Posted by Lexyaaaas View Post
The ecu doesnt care about the rich/lean on the downstream. Only the upstream. You can leave the OE O2s for the with the car in the exhaust system upstream (and add additional O2s for your standalone). But then when you tune, your stock ecu is going to freak out about the variation from the stock parameters.

You only want an O2 sim is only after the cat. Entire idea of the O2 sim is to make the ecu think theres a cat there still. You dont want a cat because cat on a turbo car is like exhaling through a straw.
Basically, the upstreams need to switch from rich to lean, and do it fast. If they don't switch, they're bad. If they don't switch fast enough, they're bad:

This diagram gives idea of good and no good regarding whether or not they're switching:


This diagram describes if it's switching fast enough. The slope of the O2 sensor signal is calculated by the ecu, and the slope must be steep - or else it is too slow:



Regarding downstreams:


You've gotta understand the purpose of the O2 sensors... We know from above that a properly controlled engine will have it's fuel mixture purposefully dithered between rich and lean - quickly. This is because catalysts work best when run that way. However, if the catalyst itself (or themselves) are working correctly, the fuel mixture should be fully oxidized and normalized. Thus, the downstream O2 sensors are there to diagnose the operation/efficiency of the catalyst...

So basically:

1. If the DSO2 switches kinda like the upstreams, it means the catalyst isn't having any effect on the exhaust, so therefore the catalyst is most definitely bad.
2. The DSO2 should read full-tilt lean for seconds at a time, else the catalyst's "oxygen storage capacity" is in question.
3. During decel fuel cut, the DSO2 needs to immediately recognize the change in fueling. This is part of the diagnostic of the sensor itself, not the catalyst.

Are the "O2 sims" smart enough to massage the signals all the time to satisfy the ecu?
05-15-2019 08:54 AM
Lexyaaaas
Quote:
Originally Posted by Alex_MP95 View Post
I've been hearing some back and forth across the forums about the O2 sims. Some say they work, and others complain that they don't completely work especially with the trick lean and rich conditions the computer will run to test the downstream O2s.
The ecu doesnt care about the rich/lean on the downstream. Only the upstream. You can leave the OE O2s for the with the car in the exhaust system upstream (and add additional O2s for your standalone). But then when you tune, your stock ecu is going to freak out about the variation from the stock parameters.

You only want an O2 sim is only after the cat. Entire idea of the O2 sim is to make the ecu think theres a cat there still. You dont want a cat because cat on a turbo car is like exhaling through a straw.
05-15-2019 08:21 AM
Alex_MP95
Quote:
Originally Posted by Lexyaaaas View Post
Quote:
Originally Posted by braintumor View Post
"register" it in Maricopa (like I do) or payson where there isnt any emissions
This is your best bet
Except that I would like to avoid having to do that.

Quote:
Originally Posted by Lexyaaaas View Post
Engineering software to reprogram/tune the stock ecu is not easy lol. Thats why everyone tries to fake the signals
/s That was the joke. Again, I've been hearing some back and forth across the forums about the O2 sims. Some say they work, and others complain that they don't completely work especially with the trick lean and rich conditions the computer will run to test the downstream O2s.
05-15-2019 08:10 AM
Lexyaaaas
Quote:
Originally Posted by Alex_MP95 View Post
Wow, it's starting to sound like cracking the OEM ECU might be an easier task.
Engineering software to reprogram/tune the stock ecu is not easy lol. Thats why everyone tries to fake the signals
05-15-2019 08:08 AM
Lexyaaaas
Quote:
Originally Posted by braintumor View Post
"register" it in Maricopa (like I do) or payson where there isnt any emissions
This is your best bet
05-15-2019 08:07 AM
Lexyaaaas Kind of skimmed this thread so sorry if majority of this has been said.
IS300 ecu is complex, you cannot tune the stock ecu (like you can with an Evo ecu which is ROM). You always have to run 2 ecus to keep all the nice interior stuff working, literally everything needs the stock ecu in place. Even when you run a standalone people are utilizing the stock ecu.

If you cant get an emissions waiver, I would just start with another chassis that you dont have to take to emissions. This car is OBD2 meaning, its probably going to be a very long time before its considered emissions "exempt".
05-13-2019 02:02 PM
VegasIS3 I literally just passed smog with my o2 sims installed so....they work fine for OBD2 testing. As for the piggyback tune not staying set, it's generally because the computer reads fuel trims and makes adjustments to long term fuel trims as a result. It's very important to monitor what the stock ECU is seeing in regards to fuel trims and adjusting the piggyback to keep the trims in line with stock conditions.
05-12-2019 09:08 PM
braintumor "register" it in Maricopa (like I do) or payson where there isnt any emissions
05-12-2019 07:56 AM
Alex_MP95
Quote:
Originally Posted by Hodgdon Extreme View Post
Recently, on ClubLexus I think, I was corresponding with a guy that a catalyst equipped turbo IS300 with a standalone in parallel with the toyota ECU. His standalone was only doing the fueling/sparking - the Toyota ecu was fully hooked up otherwise. From his description of the setup, it sure sounded to me like it oughtta pass the O2 monitors - but it didn't, and he'd been screwing with it a lot.
Wow, it's starting to sound like cracking the OEM ECU might be an easier task than trying to make it happy with false signals and whatnot. Alright, I'll have to try out the Arduino option. That sounds like a pretty sure bet as long as I can get it to mirror the output of a stock ECU perfectly.

Actually, now that I'm thinking about it, there was a USDM Supra TT IIRC. That ECU would have OBDII and the tables to handle emissions and boost. But I believe people said there wasn't any VVTi available on those cars either so I'd have to either find a way to mesh the two ECUs, or get a non VVTi head. But that still leaves the question of failing the test because the computer picks up a different VIN than what's on the car.

It sounds like I have my options though. Thank you Hogdon Extreme. You have been a fountain of knowledge and ideas.
05-12-2019 01:15 AM
Hodgdon Extreme
Quote:
Originally Posted by Alex_MP95 View Post
I know a lot of people swear by the O2 Sims, but could the same result be achieved by leaving the O2s in and running high flow cats? Or do you have to run a sim if you're running boost on the GE?

And as to the piggy back, I've been seeing conflicting stuff on those. Someone on club Lexus was saying that the ECU will revert and start screwing with the piggy back on a weekly basis so you have to keep the ECU from going to a ready state to fix it. I don't know if you have any more info on the piggy backs, but that would be much appreciated.

Are there any standalones that let you do OBDII output?
Mind you, I've not tried O2 sensor "anti foulers" or sims on anything newer than my 1998 Mustang Cobra, back in the day. At that time, you could simply insert some "MIL eliminators" into the harness between the ecu and the O2 sensors, and they would condition the signal to something the ecu wouldn't be angry with.

That said, 1998 was only the 2nd mandatory year of OBD-II, and the monitors were pretty crude back then. Speaking from my experience as an OBD2 calibration engineer for an OEM, I can tell you the way the ecu tests all of the emissions control equipment (these are called "monitors") have gotten extremely sophisticated. The ecu watches the sensor inputs and carefully chooses its opportunity to examine specific ones. In some cases, the ecu can purposefully skew engine fueling a little (both rich and lean), and watch for the appropriate response from the sensors. If the ecu KNOWS it has over/under fueled the engine slightly, if the sensors are working correctly, they had BETTER respond accordingly, and at the right TIME... Else something is wrong with the sensor --> and you get the MIL.

My point: It's hard to imagine a little simulator thingie that's going to create the correct O2 signals all the time to satisfy the ecu.

Recently, on ClubLexus I think, I was corresponding with a guy that a catalyst equipped turbo IS300 with a standalone in parallel with the toyota ECU. His standalone was only doing the fueling/sparking - the Toyota ecu was fully hooked up otherwise. From his description of the setup, it sure sounded to me like it oughtta pass the O2 monitors - but it didn't, and he'd been screwing with it a lot.
05-11-2019 11:05 PM
Alex_MP95
Quote:
Originally Posted by mesooohoppy View Post
as vegas said. you will never pass a visual. it might be worth to call a couple local smog shops and see how they can help you.
Luckily we don't have a visual inspection here, but we also don't have independent shops to do the emissions testing out here either. The testing is done at Arizona Department of Transportation owned and operated facilities. The just plug in an OBDII reader, test at idle, then at revs, and then the gas cap. So no bribery to get a pass unfortunately.

So I don't have to pass an inspection, but I would like to pass the OBDII plug in test and keep it as legal as possible so that I can avoid any major trouble with getting my daily registered. Just enough so they don't get suspicious.
05-11-2019 10:58 PM
Alex_MP95
Quote:
Originally Posted by VegasIS3 View Post
I'm planning to do exactly this. I think NA-T would be your best bet and that's what I'm doing. You'd have to use o2 sims and a piggyback ecu to keep the stock ecu happy for emissions monitors and also to prevent a check engine light from the engine seeing boost. Also the fuel trims will be out of wack with the turbo. Obviously it's not going to pass visuals with the turbo on it to an honest tech.
I know a lot of people swear by the O2 Sims, but could the same result be achieved by leaving the O2s in and running high flow cats? Or do you have to run a sim if you're running boost on the GE?

And as to the piggy back, I've been seeing conflicting stuff on those. Someone on club Lexus was saying that the ECU will revert and start screwing with the piggy back on a weekly basis so you have to keep the ECU from going to a ready state to fix it. I don't know if you have any more info on the piggy backs, but that would be much appreciated.

Are there any standalones that let you do OBDII output?
05-11-2019 10:51 PM
Alex_MP95
Quote:
Originally Posted by Hodgdon Extreme View Post
The OBD scanners all follow an ISO communication protocol that is well documented. It would be possible to program a microcontroller (arduino would be plenty powerful for this)...
https://learn.sparkfun.com/tutorials...ith-obd-ii/all
That's definitely an idea that seems pretty straightforward to implement. The site you gave had a ton of good info in it. Definitely the way to go if I can't do this "legally" so to speak. I would definitely need to find a way to pass RPM input to the Arduino though so that when the tester revs the engine it will actually show that.

And thank you to everyone giving legitimate thought and answers in this thread. Most of the answers I've seen on similar threads have been "move to somewhere without emissions" or "use search noob".
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