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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » Air Fuel Ratio

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Author	Topic: Air Fuel Ratio

willz

Member
Posts: 2

Air Fuel Ratio
on: May 22, 2011 (GMT)

The Air Fuel Ratio gauge in the torque app seem to be wrong. All the time shows the same value 15.8. Any RPM.

piemmm

Administrator
Posts: 6629

Re: Air Fuel Ratio
on: May 22, 2011 (GMT)

Hi what fuel type are you using?

rajivc666

Member
Posts: 2

Re: Air Fuel Ratio
on: May 29, 2011 (GMT)

I get most of the readings myself except for liters/hour and a/f ratio. A/f ratio is blank and not updated. I get both these readings with obdscope(symbian) on the same car and using same obdlink.

piemmm

Administrator
Posts: 6629

Re: Air Fuel Ratio
on: May 30, 2011 (GMT)

AF Ratio does work – I’ve been using it in my own vehicle – are you using the latest version 1.4.69?

Aaron407

Member
Posts: 20

Re: Air Fuel Ratio
on: May 30, 2011 (GMT)

I also haven’t had any luck with the Air Fuel Ratio PID on my 2009 G8 GT. It just has a single ‘-‘ (dash) where a value would normally be displayed. Any ideas?

piemmm

Administrator
Posts: 6629

Re: Air Fuel Ratio
on: May 30, 2011 (GMT)

Hm, it’s possible your vehicle doesn’t support the PIDs required for working out AFR, however there’s another place to get the info so I’ll see what I can do for the next update for you

Aaron407

Member
Posts: 20

Re: Air Fuel Ratio
on: May 30, 2011 (GMT)

I’ve previously used a handheld tuner to read commanded AFR, so it definitely capable of reading the PID. If you have any suggestions I’d be quite happy to be a guinea pig for testing

The car is a 2009 Pontiac G8 GT and, according to the diagnostics page, uses OBDII protocol ISO15765-4CAN11/500.

However, I sincerely apologize for hijacking this thread since it has diverted from the OP’s concern.

YelloEye

Member
Posts: 38

Re: Air Fuel Ratio
on: May 31, 2011 (GMT)

I had to create my own afr using 0134 pid.

Aaron407

Member
Posts: 20

Re: Air Fuel Ratio
on: May 31, 2011 (GMT)

Quote from YelloEye on May 31, 2011
I had to create my own afr using 0134 pid.
Would you mind offering any additional information about how you set up the PID, including the equation, limits, etc.?

prnit

Member
Posts: 1

Re: Air Fuel Ratio
on: May 31, 2011 (GMT)

I was also very interested in this paramater but it is not working on my VOLVO S60 2006 year 2,0T :(((

piemmm

Administrator
Posts: 6629

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

Looks like AFR won’t work until the engine is warm. I’ll sort this out with better info
in the next version. You will have to restart torque when the engine has warmed up (for it to notice AFR is working)

Ian

YelloEye

Member
Posts: 38

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

No need to do that, the sensor spits out data soon as the key is on. It just doesn’t get the data correct until the sensor is warmed up. Same thing for the narrow band sensors.

What PID are you using for the programmed AFR? Mine doesn’t work with the preprogrammed one.

Quote from admin on June 1, 2011
Looks like AFR won’t work until the engine is warm. I’ll sort this out with better info
in the next version. You will have to restart torque when the engine has warmed up (for it to notice AFR is working)

Ian

YelloEye

Member
Posts: 38

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

The following is the wiki page on PIDs that lists the information you need to create any standard PID.
http://en.wikipedia.org/wiki/OBD-II_PIDs

But here is the specific information you’re wanting:
address: 0134
name: AFR (or Lambada)
minimum: 8 (or 0)
maximum: 29.4 (or 2)

Now input one of these two equations. Most are used to seeing AFR with a gasoline motor. If you are using a different fuel such as E85 or Diesel the AFR formula won’t work and you’ll need to change that last value out for the stoichiometric value for that fuel.

Equation for AFR (8-29.4): (((A*256)+B)/32768)*14.68
Equation for Lambada (0-2): ((A*256)+B)/32768

Quote from Aaron407 on May 31, 2011
Quote from YelloEye on May 31, 2011
I had to create my own afr using 0134 pid.
Would you mind offering any additional information about how you set up the PID, including the equation, limits, etc.?

Aaron407

Member
Posts: 20

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

I agree that there should be no need for the engine to reach operating temperature before AFR is measured. The heating element in a narrowband oxygen sensor very quickly heats the sensor itself to operating temperature in order to better control the emissions-purposed startup AFR. I personally have measured this a number of seconds just after startup, at which point an AFR value was indeed reported.

I’ll give your equation a go and see if it works. Thanks for the help!

piemmm

Administrator
Posts: 6629

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

On some engines that is the case, but it will be running at open/closed loop depending on the conditions, for example, this explains it perfectly:

http://www.thirdgen.org/open-loop-closed-loop

So you may not, in fact, get a reading for some time.

Aaron407

Member
Posts: 20

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

Ok, there seems to be some confusion here. What I’m personally looking for is commanded AFR, not measured. Regardless of the state of the engine in terms of closed or open loop, regular cruising or startup or power enrichment, there’s a basic target AFR value calculated by the ECM to include in the injector pulse width equation. This is the value that I’m looking to have reported. It in no way depends on the O2 sensors, but merely the programming in the ECM, and is available anytime the engine is running.

Also, I tried YelloEye’s AFR PID, unfortunately to no avail. I tried with address 0134, as well as 220134, but ended up with a ‘-‘ where a value would normally be shown. Any ideas?

piemmm

Administrator
Posts: 6629

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

Okay, 0134 is the PID you want (mode 1, pid 34) , though that is the O2 measured, not commanded.

Commanded AFR isn’t a standard PID, so you’ll most likely be after a General Motors Mode 22 PID. The GM PIDs that I have collected so far don’t include AFR at the moment, so the best bet is spending some time on google (I happen to be looking for IAT2 PIDs for GM at the moment so will keep my eyes open)

Aaron407

Member
Posts: 20

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

I’ll do a few searches, ask around, try a few, and report back if I have any success.

piemmm

Administrator
Posts: 6629

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

Think I’ve found it

PID: 22119E

Equation: (Not sure). It could be:

A
A/100
A/10
(something else)
((A*256)+B)/100 (doubt this)

You’ll have to try with ‘A’ and see what you get for what should be stociometric, we can probably work it back from that with a little common sense.

Aaron407

Member
Posts: 20

Re: Air Fuel Ratio
on: June 1, 2011 (GMT)

The 22119E PID is already listed as a custom PID (for me anyway) that came with the last update, and is titled AFR (Commanded). I tried it out previously and just got a ‘-‘ result. The current equation shown in the custom PID list for it is A/10. Can the equation itself cause a null response to be shown for a PID that might actually be reporting?

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