System too lean error codes

[johnatg]

The 'tester' referred to in the manual page is not Techstream - it's a hand held hardware device - known as an 'Intelligent Tester', which Lexus dealers have. You can buy them but they cost about £300 AIR.

You can't do any of this testing with Techstream, but it does give you live engine data on fuel trims etc.

[Shahpor]

Where did you find these?

They look like they are from the manual, so in which section did they list these diagrams?

One thing that springs to mind is that what you have posted says turn the car on and test at 2500rpm for 90 seconds.  Is this with the engine cold?  If so, that will affect the readings since the car will naturally run rich whilst cold.

[Shahpor]

3 minutes ago, johnatg said:

The 'tester' referred to in the manual page is not Techstream - it's a hand held hardware device - known as an 'Intelligent Tester', which Lexus dealers have. You can buy them but they cost about £300 AIR.

You can't do any of this testing with Techstream, but it does give you live engine data on fuel trims etc.

This is true John, but as you can see from the screenshot I posted earlier, the live engine data should include the voltage values for the sensors, so I am assuming you can still compare those to what is in the manual?

[johnatg]

To an extent yes - It's a while since I've hooked up my Techstream - I think it's quite hard to get the actual voltages read because it kind of lags what the engine is doing dynamically.

The Workshop manual never seems to refer to using Techstream - they do everything with the Intelligent Tester. But Lexus and Toyota dealers do use Techstream but I think only for setting equipment options and things like that. It's handy to drive with Techstream connected up, but for heaven's sake get someone else to read what the computer screen is saying whilst you're driving!

[james250]

25 minutes ago, Shahpor said:

Where did you find these?

They look like they are from the manual, so in which section did they list these diagrams?

One thing that springs to mind is that what you have posted says turn the car on and test at 2500rpm for 90 seconds.  Is this with the engine cold?  If so, that will affect the readings since the car will naturally run rich whilst cold.

I got pm'ed the link from another lexus forum but was told it's from the lexus service manual. I think it says start engine and run it at 2500rpm for 90 seconds to Warm up the Air-Fuel Ratio sensors. After that to do the 3 scenario monitoring. But i guess will there be any harm waiting longer to warm the engine as my engine hasn't been started this week so it will be really cold so would think might be worth while running engine for a bit before hand

[james250]

An interesting video, seems to show Techstream being able to read AFR data. Surely if the Intelligent Sensor can read data via the OBD port then why couldnt TechStream. As long as the software is capable of it.

[johnatg]

In the interests of science, I've been out and played with my Techstream a bit - and surprised myself.

Here are a few snaps of live engine data, concentrating on the oxygen sensors (upstream and downstream). The engine was cold when I started (see it says 5 deg C somewhere) and warmed up whilst I was taking the pics and working out what I wanted to show.

Don't worry James - by the time you've got the Techstream connected and worked out what's what with the program the engine will be nicely warmed up if you connect the Techstream as soon as you get in the car and start the engine!

Note that the upstream sensors read about 3.3v and the downstream ones show lambda about 1.000. Pay no attention to the numbers - I just chose the pics at random from the ones I took, then cropped and resized them. The numbers are just to differentiate them as I saved them.

[Shahpor]

That is quite interesting John.  Thanks for doing that.

So it seems that 3.3V is about right then?

Also, I have actually never used the graph function of TechStream before.  How do you access it?  Thanks.

[johnatg]

Yes - I'm sure the wideband sensors run at about 3.3V with a stoichometric mixture. The older type downstream sensors vary between about 0.1 and 0.9 volts but Techstream just reports lambda, which we discussed somewhere above.

To get the graphs you click on whichever parameters you want on the top 3 screens above. The particular row is then highlighted blue. Then you click on the graph icon at the bottom of those screens. You get the parameters shown as stacked graphs (4th pic down). You can then choose to show any one of them full screen - there are menu, full screen and graph type buttons on each graph. I guess there's a way of setting the timebase but I haven't explored that.

[james250]

@johnatg thanks. Those are great screenshots. Will see how mine looks when I connect it up. Will post an update once I have done so.

[iwonder]

Click the bottom with arrows pointing left and right. And remove as much data as possible. Your ms reading is too high to accurately test sensors. Dealer techstream runs at 1-300ms to give you live data without lag between Comms. Slow live data and lead to incorrect diagnosing

[james250]

1 hour ago, iwonder said:

Click the bottom with arrows pointing left and right. And remove as much data as possible. Your ms reading is too high to accurately test sensors. Dealer techstream runs at 1-300ms to give you live data without lag between Comms. Slow live data and lead to incorrect diagnosing

Sorry might sound silly but i'm a bit lost. Do you mean disable reporting too much data to reduce data reading lag? So the more data it is reading the more lag there will be? is that what you mean? How do you select the data that you want only? and what is the ms reading you are referring to?

[iwonder]

The speed of the data link. Click primary and select a different list of data or click the arrows at the bottom to move data from visible and hidden. Just keep the data that you need to test, so lambda and rpm for what your doing. It will be more reliable data to compare live or you will have to keep saving the data to view back to cancel out the lag. My mongoose cable operates at 100-300ms.

[Texas]

ms = millisecond,. The time taken for the device to show the information after it has happened. Known as Lag.

If you have a large lag then you will not be seeing things as they actually happen but if you record a session then when you analyse it afterwards you can see how different values interact with each other, make sense?

Paul m.

[johnatg]

Yes - and also the timebase. I've looked at the Techstream 'Help' section - if you look under 'Diagnostics functions....'/'Graph function (data monitor)' - scroll down to Menu - Time setup, it shows you how to adjust the horizontal axis to show the data over different time periods. And a whole lot of other settings as well. Not tried it live, just on my desktop so far.

Must really spend some time with Techstream - it obviously can do way more than I thought - or at least have tried so far!

[james250]

Just installed techstream. Going to play around with it later. What section is the error codes stored and pending in? Is there different sections for error codes?

[johnatg]

Connect to the vehicle, choose the appropriate model, year etc, then go on to System Select, click on 'engine' then 'Trouble Codes'.

You can only find out what does what when it's connected to the car.

Check out the 'help' section in the program - it's really quite helpful!

[LennyLexus]

My system lean errors have been fixed, nothing to do with O2 sensors, this is common and expensive misdiagnosis.

 

[Texas]

Hi, did you manage to install Techstream and connect it to your 250 and get an outcome for your O2 sensor dilemma?

Paul m.

[madasahatter]

On 8/24/2017 at 6:52 PM, is200 Newbie said:

Got to agree with Normski - its a well worthwhile job to do - you should see a difference in the running of the car after replacing both. I never done the PCV valve when changing the sensors on mine - to be honest I did not know it could be done. Job for the future.

The hardest thing about replacing bank 1 is taking the engine covers off.

Bank 2 is a bit more tricky, not because theres mountains of kit to remove, because theres not a lot of space to work in - you do need to remove battery and the electronic kit underneath which I think is the ECU so don't bang it around - take your time and you will see how easy it is to do. The sensors I bought came with a small sachet of thread copperease grease type of stuff so there may not be a need to purchase any specific for the job (not that its expensive stuff anyway)

Remember to disconnect your battery before unplugging connectors - but as you progress you will need to anyway

 

Let us know how you get on.

I have same problem the one under the Battery tray. Where did you purchase sensor from. The ecu unit is for the electronic steering.

[is200 Newbie]

7 hours ago, madasahatter said:

I have same problem the one under the battery tray. Where did you purchase sensor from. The ecu unit is for the electronic steering.

I bought it from the US - Rockauto I think

 

[normski2]

Me too...Rockauto in the USA

[james250]

Sorry for late reply about this. got really busy at work so car work had to be paused. Anyway, finally got round to running Techstream on the car and below is a screenshot of what I got. Whatever RPM i was doing it wasn't really moving much in terms of voltage. I assume these AFS sensors are no good. any thoughts?

 

[madasahatter]

On 2/27/2018 at 11:36 AM, madasahatter said:

I have same problem the one under the battery tray. Where did you purchase sensor from. The ecu unit is for the electronic steering.

As i understand bank one sensor one is under the Battery tray. On the video i watched on an American car. Have i got this wrong if its on the drivers side is it an easier fix.

[normski2]

Bank 1 Sensor 1 is on drivers side for UK. 

Bank 2 Sensor 1 is under Battery tray.