[iqraceworks]

I was doing some logging with MHD the other day and I noticed that at idle and slow cruising...my AFR's are jumping all over the place. Usually between 13.9 and 15.2....but it's never constant, they are always jumping around. The cars runs great, idles nice and smooth....no issues.

I'm assuming this is normal?? At wide open the AFR's are very smooth and constant as they slowly change depending on what the tune/DME is calling for.

[borskii]

Funny, I actually have a log of my idle. I think it was at a stoplight after I was cruising for a while.

Anyways, seeing 14.5 - 15.0, average around 14.7. I'm on index 11. Stock pump.

[eastsidaz]

Originally Posted by iqraceworks

I was doing some logging with MHD the other day and I noticed that at idle and slow cruising...my AFR's are jumping all over the place. Usually between 13.9 and 15.2....but it's never constant, they are always jumping around. The cars runs great, idles nice and smooth....no issues.

I'm assuming this is normal?? At wide open the AFR's are very smooth and constant as they slowly change depending on what the tune/DME is calling for.

Same here bounces between 13.9 and 15'ish like you said. I hooked up inpa and noticed in the live adaption mixtures my post cat bank 2 o2 sensor is acting weird. Voltage drops low and back to normal. bank 1 is perfect. resetting adaptions only works for a few mins. So i got a new o2 on the way

[iqraceworks]

Originally Posted by GovernUrMental

Same here bounces between 13.9 and 15'ish like you said. I hooked up inpa and noticed in the live adaption mixtures my post cat bank 2 o2 sensor is acting weird. Voltage drops low and back to normal. bank 1 is perfect. resetting adaptions only works for a few mins. So i got a new o2 on the way

Thanks....I will check the readings from my 02's and see what they look like. With 100k miles on them...it would surprise me if one or more needs replaced.

[Soden82]

14.5-15 for me. O2 voltages were all within spec when I tested mine.

[iqraceworks]

Originally Posted by Soden82

14.5-15 for me. O2 voltages were all within spec when I tested mine.

What's the spec that the voltages should be in?

[CarAbuser]

You can check the fuel mode parameter. If it's anything other than 2 then that could be the cause. Number 3 can cause oscillations in AFR. Just normal engine diagnostic and adaptation routines so no need to buy parts if that's the case.

N54 Fuel Sub Modes:
0: No sub-mode
1: Optimal
2: Lambda 1
3: Test O2
4: KHM_DOE_LR (cat heating double injection with smooth-running spreads)
5: KHM_DOE_EM (cat heating double injection with emission-optimized spreads)
6: Component protection
7: KHM_ZW (catalytic converter heating with ignition angle intervention)
8: Desu_puls
9: NoxKat_reg
10: KHM_LR (Katheizen- single injection with smooth running-optimized spreads)
11: KHM_EM (cat heating single injection with emission-optimized spreads)
12: KHM_ZW_DE (catalyst heating with ignition angle intervention and desulfation)
13: KHM_LR_DE (Katheizen- single injection with smooth running optimized spreads and Desu)
14: KHM_DOE_LR_DE (cat heating double injection with spreads optimized for smooth running and DESU)
15: Emergency run
16: LAMTEST (lambda test)
17: GL_ZSK (equality)
18: DESU_FETT
19: Forced mixture adaptation
20: Spool
21: full load
22: Injector adaptation

[iqraceworks]

How do I check (and change if needed) the fuel modes? iNPA? Other?

[CarAbuser]

MHD has it as a logging parameter. I don't think you'll see it anywhere else.

[iqraceworks]

Originally Posted by CarAbuser

MHD has it as a logging parameter. I don't think you'll see it anywhere else.

So once you find out what "fuel mode" you are running....how do you change it??

[eastsidaz]

Always fuel mode 2 which is normal once warmed up and 20 in spool

So is this normal? (Lambda voltage after cat bank 2) although they both dipped during clip its normally just bank 2

afr bounce 14-15. Others i've seen idle smooth
https://datazap.me/u/formation/idle?log=0&data=18-19-23

[_N54]

I'm flashed to stock because I have a smog inspection, but I just checked my AFR with MHD @ idle and it's reading 14.8-14.9

[iqraceworks]

Originally Posted by ///S58

I'm flashed to stock because I have a smog inspection, but I just checked my AFR with MHD @ idle and it's reading 14.8-14.9

How much does it fluctuate? Does it just sit there at 14.8-14.9 when it's idling?

[Soden82]

Originally Posted by iqraceworks

What's the spec that the voltages should be in?

The primaries should be 0-2V, but mostly around 1-2V. Secondaries should be 0-1V.

When revving/accelerating both banks should mirror each other closely on the primaries and secondaries

[iqraceworks]

Mine really seems to jump around pretty good at idle and light cruising......but as soon as I start to get on the car, it stabilizes out. I'm guessing that as long as the arf is steady when there is a load on the motor... everything is good? I need to check both banks and make sure they are equal.

[Ilma]

Lol.....you guys really should use Tunerpro and open up your bin file to look at the commanded Air Fuel ratios.

That table calls for 14.7 AFR for almost 75% of the time, especially at idle.

[Ilma]

Originally Posted by iqraceworks

I was doing some logging with MHD the other day and I noticed that at idle and slow cruising...my AFR's are jumping all over the place. Usually between 13.9 and 15.2....but it's never constant, they are always jumping around. The cars runs great, idles nice and smooth....no issues.

I'm assuming this is normal?? At wide open the AFR's are very smooth and constant as they slowly change depending on what the tune/DME is calling for.

Don't know how much fluctuation is normal......but I have seen in INPA a section for ongoing adaptations for idle/rough running.

It is normal for some degree of AFR and even timing fluctuation at idle as the DME is constantly adapting values to achieve a smooth idle, and this is an ongoing process.

But I don't know how far adaptation can go before it is out of range and considered abnormal.

You can monitor the voltages and values in INPA under the rough running section......

It will indicated in a bar graph whether you are within normal values or not.

[iqraceworks]

Originally Posted by Ilma

Lol.....you guys really should use Tunerpro and open up your bin file to look at the commanded Air Fuel ratios.

That table calls for 14.7 AFR for almost 75% of the time, especially at idle.

The AFR itself isn't the issue.....it's how much it fluctuates around at idle. I know the target is around 14.7:1 - 15.0:1.....but mine seems to always jump around between 13.8 to 15.1...even at light throttle. When I get on the gas, it stabilizes out.

It idles very smooth....no issues with it at all. I was just curious at the fluctuations.

[_N54]

Originally Posted by iqraceworks

How much does it fluctuate? Does it just sit there at 14.8-14.9 when it's idling?

Yes it just sits at 14.8-14.9 consistently changing around that ratio. I'm trying to pass emissions and my Oxygen Sensor monitors is INCOMPLETE and all others are completed so I don't even know if I have bad o2's or not, but likely ill be changing all 4 just to get it out the way since the N54 are notorious for bad o2's.

[iqraceworks]

Yeah..that's odd. I've never seen AFR's that "title" on a motor when it's idling. Usually they always seem to fluctuate some....but only +/- .1 is almost like the 02's aren't working right..

[Ilma]

Originally Posted by iqraceworks

The AFR itself isn't the issue.....it's how much it fluctuates around at idle. I know the target is around 14.7:1 - 15.0:1.....but mine seems to always jump around between 13.8 to 15.1...even at light throttle. When I get on the gas, it stabilizes out.

It idles very smooth....no issues with it at all. I was just curious at the fluctuations.

You should have read my post after that one where I talk about just that.

Just for you on my drive today, I monitored my AFR's at idle and they fluctuated between 13.9 up to 15.8 constantly.

My ignition timing varied as well.

My idle is very smooth.

I think what you are seeing on your own car is within normal ranges.

But the only way to be sure is to check the rough running and O2 values in INPA and see if they are falling within the range considered a normal window.

You're welcome!

[iqraceworks]

Thanks!! I will hook up INPA and do some checking tonight. I'm also curious if both O2's are fluctuating around the same amount...of if one is much more even than the other. I forgot INPA has that "rough running" screen....

It does sound like your AFR's fluctuate just like mine...so I'm sure it's normal, but I still want to see what INPA is showing.

Thanks again!