× A place to discuss hardware/software and diagnostic procedures

Air/fuel ratio sensor testing thread

More
08 Jan 2020 17:55 #36433 by Orchid70
Replied by Orchid70 on topic Air/fuel ratio sensor testing thread
A question!
Volvo V70 (2001<) uses Lambda units for STFT and LTFT and not % per cents!

So I can have:
STFT: 0,98
LFTF: 1,02
At idle at 750 rpm

SO Im guessing that would equal to:
-2%
2%

That Lambda 1 is 0.

Anyone knows? I do have pictures from both Vida and SnapOn.

Please Log in or Create an account to join the conversation.

  • Tyler
  • Tyler's Avatar Topic Author
  • Offline
  • Moderator
  • Moderator
  • Letting the magic smoke out since 2011
More
08 Jan 2020 19:02 #36434 by Tyler
Replied by Tyler on topic Air/fuel ratio sensor testing thread
That's correct! As far as I know, anyway. I don't see Volvo of that vintage very often any more. :silly:

But, most every application I've seen of Lambda PIDs works exactly as you described.
The following user(s) said Thank You: Orchid70

Please Log in or Create an account to join the conversation.

More
09 Jan 2020 07:56 #36459 by Orchid70
Replied by Orchid70 on topic Air/fuel ratio sensor testing thread
Thank you - I was just beeing sure =)
This bloody car needs to be resett by taking off the battery negative - emptying every possible memorey by leaving it off long enough or turning the start key - after that this (quote from VIDA) - this after changing any faulty parts on fuel/air/exhaust system as well as erasing the codes:

The rpm is high/low during engine braking to a stop. This is so because idle control needs time to learn how much air the engine needs when the engine runs at idle. The adaption takes place every time the engine idles. Only a limited amount of adaptions is allowed each time. This means that you have to leave idle every once in awhile for the system to finish adapting.

One way to do that is to run the engine warm and then let it idle. If the vehicle is equipped with automatic transmission, gear position D (drive) shall be used.

With some minute's interval, load the engine a little by revving it for a few seconds. Then you let the engine return down to idle.

Test-drive the vehicle to decide if the system has finished adapting or not.
END quote.

Please Log in or Create an account to join the conversation.

More
02 Apr 2020 11:58 #38855 by MattH
Replied by MattH on topic Air/fuel ratio sensor testing thread
Wow! How am I just now seeing this? Great explanation Mr. Danner! Can't thank you enough for your industry contributions.

Please Log in or Create an account to join the conversation.

  • Dylan
  • Dylan's Avatar
  • Offline
  • Moderator
  • Moderator
  • Belgium, Europe
More
03 Apr 2020 14:20 #38887 by Dylan
Replied by Dylan on topic Air/fuel ratio sensor testing thread

MattH wrote: Wow! How am I just now seeing this? Great explanation Mr. Danner! Can't thank you enough for your industry contributions.


Don't forget to thank Tyler who has put so much effort into this thread :)
The following user(s) said Thank You: Noah, Tyler, Andy.MacFadyen

Please Log in or Create an account to join the conversation.

More
23 Oct 2020 20:38 #43944 by Lowboybrian
Replied by Lowboybrian on topic Air/fuel ratio sensor testing thread
So question... is the heater circuit the only thing that can be tested by taking an ohm measurement of the heater? And also verifying the 3.3 and 3.0 (toyota) voltages on the signal wires? Curious if any other part of the sensor can fail or slowly deteriorate that may cause inaccurate readings? I tested 2 different toyotas just trying to get a sense of what I should see but they are different. 2016 Corolla AF voltages go to 4.96 v (lean) on decel fuel cut and about 2.5 v at WOT. 2002 Sienna (V6) both AF voltages barely get above 4 v and between 2.5 v and 3 v at WOT. The Corolla downstream O2 reacts exactly as I would expect with each however the Sienna downstream is kinda all over the place because it rarely goes into the decel fuel cut off. It reacts as expected during WOT but doesn't go into an open loop drive/ decel fuel cut unless at high speed/rpm. Maybe thats just a difference in the ECM strategy from 2002 to 2016?... or would an aging AF sensor show itself in the form of voltages not going as high or as low as they should? The Sienna has a Cat Efficiency code that pops up every few months or so which is why I'm trying to get a read on the downstream sensor.... and the possibility of the AF sensors/ decel fuel cut issues contributing to this condition? No driveability concerns... just trying to learn more about their operation. Sorry I'm so long winded.... TIA

Please Log in or Create an account to join the conversation.

More
24 Oct 2020 10:18 - 24 Oct 2020 10:19 #43949 by Andy.MacFadyen
Replied by Andy.MacFadyen on topic Air/fuel ratio sensor testing thread

Lowboybrian wrote: So question... is the heater circuit the only thing that can be tested by taking an ohm measurement of the heater? And also verifying the 3.3 and 3.0 (toyota) voltages on the signal wires? Curious if any other part of the sensor can fail or slowly deteriorate that may cause inaccurate readings? I tested 2 different toyotas just trying to get a sense of what I should see but they are different. 2016 Corolla AF voltages go to 4.96 v (lean) on decel fuel cut and about 2.5 v at WOT. 2002 Sienna (V6) both AF voltages barely get above 4 v and between 2.5 v and 3 v at WOT. The Corolla downstream O2 reacts exactly as I would expect with each however the Sienna downstream is kinda all over the place because it rarely goes into the decel fuel cut off. It reacts as expected during WOT but doesn't go into an open loop drive/ decel fuel cut unless at high speed/rpm. Maybe thats just a difference in the ECM strategy from 2002 to 2016?... or would an aging AF sensor show itself in the form of voltages not going as high or as low as they should? The Sienna has a Cat Efficiency code that pops up every few months or so which is why I'm trying to get a read on the downstream sensor.... and the possibility of the AF sensors/ decel fuel cut issues contributing to this condition? No driveability concerns... just trying to learn more about their operation. Sorry I'm so long winded.... TIA


Fuel control with wideband sensors have improved over the years and is generally pretty tight on modern Toyotas. Sensors and cats both detoriate with age. the cat on a 2002 car is either going to be aged or been replaced with an aftermarket or possibly even de-cated. With a cat effiency code my first move would be a cat oxygen storage efficiency test.

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



Last edit: 24 Oct 2020 10:19 by Andy.MacFadyen.

Please Log in or Create an account to join the conversation.

More
26 Oct 2020 13:23 #44000 by Lowboybrian
Replied by Lowboybrian on topic Air/fuel ratio sensor testing thread
Oxygen storage looked ok compared to the Corolla which was really only about 1 sec. And not seeing the normal oscillation pattern on the rear O2 for a bad cat. I'm seeing the rear 02 going a bit wonky because of the decel fuel cut issue I think but wanted to make sure I wasn't missing anything with AF sensor voltages since I'm not as up to speed on those sensors as I'd like to be. The decel fuel cut should return to fueling at 1200 rpm according to service data but its returning between 1800-2000 rpm and its at this point the rear O2 has more rich to lean movement which I'm just guessing might be what the ecm is interpreting as an efficiency issue? But regardless I don't want to clog this great thread with trying to troubleshoot that... My main concern here was making sure I wasn't missing anything on the testing of an AF sensor and if lower/higher than normal (whatever that is) voltages possibly indicate an aging or failing sensor. I have 4 other Toyotas here, 2 being close to the same vintage that I'll test when I get them repaired. I'll start another thread on this tho. Thanks bro.

Please Log in or Create an account to join the conversation.

  • Not Allowed: to create new topic.
  • Not Allowed: to reply.
  • Not Allowed: to edit your message.
Time to create page: 0.290 seconds