[whyzee125]

Hey guys,

Looks like this is a common issue and almost nobody seems to get it resolved. I'm a little discouraged after reading all the posts but I'm determined to get to the bottom of it. The car has 95k miles and is running full e85 on a custom Wedge tune with port injection. It's been running great til 1000 miles ago and nothing had been changed when it started.

It started oscillating where the revs will visibly jump up and down and you can feel it jerk when the throttle is held steady at very light throttle and basically no load. If you let off entirely and coast, it's smooth. If you give it a little load, it's smooth. Starts and idles perfectly. But it oscillates like crazy when you hold light, steady throttle at no load.

- I replaced spark plugs with NGK 2 step colder gapped to .18 with no change
- Coils are newer and no misfires
- Vanos solenoids are original but have been cleaned once when it got vanos codes at 69k miles
- HPFP is fairly new and working properly
- Upstream O2 sensors are about a year old
- Downstream are original but I think all those do is measure cat readiness? I'm catless anyway
- I did the throttle reset thing and it made it a little less noticeable but definitely did not fix it
- I reset load and throttle adaptations with no change

Most importantly, I captured it on a log (My very first log! ) I bought the car a few months back already modded so never logged before!

Can anybody help me decipher this and give any insight as to what may be going on?

Log: https://datazap.me/u/whyzee125/oscil...-9-13-14-18-19

Thanks so much!

[Spyro235]

Change your o2 sensors anyway. It sucks, but eat the cost and know they are good. I dealt with this for months before I jsut sucked it up and ought the sensor, even though it seemed o eb reading totally fine. I can't explain it, but it worked. My AFR's would oscilate and i would have this light steady surging at lgiht cruise conditions, and I could actualyl hold my throttle pedal at about 7% and watch the rpm/ load/ AFR's oscilate up and down. I'd start there.

[Dave92N54]

Originally Posted by Spyro235

Change your o2 sensors anyway. It sucks, but eat the cost and know they are good. I dealt with this for months before I jsut sucked it up and ought the sensor, even though it seemed o eb reading totally fine. I can't explain it, but it worked. My AFR's would oscilate and i would have this light steady surging at lgiht cruise conditions, and I could actualyl hold my throttle pedal at about 7% and watch the rpm/ load/ AFR's oscilate up and down. I'd start there.

Which did you replace, all 4? Primaries? Secondaries?

[whyzee125]

Originally Posted by Spyro235

Change your o2 sensors anyway. It sucks, but eat the cost and know they are good. I dealt with this for months before I jsut sucked it up and ought the sensor, even though it seemed o eb reading totally fine. I can't explain it, but it worked. My AFR's would oscilate and i would have this light steady surging at lgiht cruise conditions, and I could actualyl hold my throttle pedal at about 7% and watch the rpm/ load/ AFR's oscilate up and down. I'd start there.

Thank you for the reply, I'll probably try this. I found another thread about this issue with a little more success than the first one I found and the solution in that one seemed to be resetting all adaptations/modules through INPA. May try this first and if that doesn't do it, I'll just do all the O2 sensors.

Originally Posted by Dave92N54

Which did you replace, all 4? Primaries? Secondaries?

It was the PO who did them but he just did the primaries I think. The upstream ones from the DPs were what he replaced. Thank you for the help!

[Dave92N54]

My question was for spyro lol I believe i'm seeing early stages of this, and recently did primary 02s but secondaries seem to be original, i've also heard of others solving the issue with new secondaries so curious to see which he replaced

[whyzee125]

Originally Posted by Dave92N54

My question was for spyro lol I believe i'm seeing early stages of this, and recently did primary 02s but secondaries seem to be original, i've also heard of others solving the issue with new secondaries so curious to see which he replaced

Ah gotcha! Good luck with yours! I'll update when I get this resolved

[Silent9n54]

Originally Posted by whyzee125

Ah gotcha! Good luck with yours! I'll update when I get this resolved

i was chasing a similar issue for months, hesitation and light stutter below 4000rpm, i just walnut blasted it and its perfectly smooth now, the issue is gone.

[Wolf 335]

Originally Posted by whyzee125

Hey guys,

Looks like this is a common issue and almost nobody seems to get it resolved. I'm a little discouraged after reading all the posts but I'm determined to get to the bottom of it. The car has 95k miles and is running full e85 on a custom Wedge tune with port injection. It's been running great til 1000 miles ago and nothing had been changed when it started.

It started oscillating where the revs will visibly jump up and down and you can feel it jerk when the throttle is held steady at very light throttle and basically no load. If you let off entirely and coast, it's smooth. If you give it a little load, it's smooth. Starts and idles perfectly. But it oscillates like crazy when you hold light, steady throttle at no load.

- I replaced spark plugs with NGK 2 step colder gapped to .18 with no change
- Coils are newer and no misfires
- Vanos solenoids are original but have been cleaned once when it got vanos codes at 69k miles
- HPFP is fairly new and working properly
- Upstream O2 sensors are about a year old
- Downstream are original but I think all those do is measure cat readiness? I'm catless anyway
- I did the throttle reset thing and it made it a little less noticeable but definitely did not fix it
- I reset load and throttle adaptations with no change

Most importantly, I captured it on a log (My very first log! ) I bought the car a few months back already modded so never logged before!

Can anybody help me decipher this and give any insight as to what may be going on?

Log: https://datazap.me/u/whyzee125/oscil...-9-13-14-18-19

Thanks so much!

You have done everything but the injectors.

[whyzee125]

Originally Posted by Silent11N54

i was chasing a similar issue for months, hesitation and light stutter below 4000rpm, i just walnut blasted it and its perfectly smooth now, the issue is gone.

Originally Posted by Wolf 335

You have done everything but the injectors.

Forgot to mention, injectors are index 12's from a few years ago.

I found this thread where a few people had success with a full reset of all the modules in INPA.

https://www.e90post.com/forums/showthread.php?t=1323769

I tried it yesterday and am happy to report she's running even better than before the issue started. This definitively cured it for anyone else experiencing the same thing.

[Wolf 335]

Originally Posted by whyzee125

Forgot to mention, injectors are index 12's from a few years ago.

I found this thread where a few people had success with a full reset of all the modules in INPA.

https://www.e90post.com/forums/showthread.php?t=1323769

I tried it yesterday and am happy to report she's running even better than before the issue started. This definitively cured it for anyone else experiencing the same thing.

Thanks for the update.

Could you also proved another update after a full week or two?

When you reset all modules in INPA did you get any codes pop up, in particular for throttle position?

[whyzee125]

Originally Posted by Wolf 335

Thanks for the update.

Could you also proved another update after a full week or two?

When you reset all modules in INPA did you get any codes pop up, in particular for throttle position?

Will do. I've put almost 100 miles on it so far and buttery smooth still.

I had a super rough startup where it sounded like it had a cam in it and the idle was jumping up and down. Did the throttle reset (hold gas for 30 secs, etc.) and after that it started right up and idled perfectly. Drove around for it to relearn and honestly it ran great from the get go. Very happy.

[Spyro235]

Originally Posted by Dave92N54

My question was for spyro lol I believe i'm seeing early stages of this, and recently did primary 02s but secondaries seem to be original, i've also heard of others solving the issue with new secondaries so curious to see which he replaced

I did my primaties and reset o2 adaptations. Resetting my adaptations actually solved my problems temporarily each time.

[whyzee125]

Originally Posted by Spyro235

I did my primaties and reset o2 adaptations. Resetting my adaptations actually solved my problems temporarily each time.

Did you reset in INPA? I reset all the ones MHD would let me reset about a week before and it definitely improved but did not solve it.

[rush jamaica]

Originally Posted by whyzee125

Did you reset in INPA? I reset all the ones MHD would let me reset about a week before and it definitely improved but did not solve it.

You have to do the rest adaption property or it won't work

[blaster3500]

Originally Posted by whyzee125

Did you reset in INPA? I reset all the ones MHD would let me reset about a week before and it definitely improved but did not solve it.

Do you mind sharing how you reset adaptations in INPA?

[whyzee125]

Originally Posted by rush jamaica

You have to do the rest adaption property or it won't work

Yes, my issue has been solved but I was letting people know MHD won't fix this.

Originally Posted by blaster3500

Do you mind sharing how you reset adaptations in INPA?

I found this thread: https://www.e90post.com/forums/showthread.php?t=1370760

and had my go-to coder guy do it remotely. I use SD BMW coding.

[whyzee125]

Hey guys, resetting ALL adaptations in INPA made the car run fantastic for about 500 miles then it came back. Since my lambda's were all over the place I also replaced the rear O2's and had my coder reset lambda adaptations. It's been 50 miles and now it's back again.

-New rear O2 sensors (what a pain)
-New Eldor coils
-Reset adaptations again (only lambda ones this time)

I have shadow codes for misfires on cylinders 5 and 6 but they don't give a date in the code history? Resetting the adaptations turns it into a whole new car for about 500 miles, then it's back. There's a log in my first post and I just took another log today which looks the same. I felt fairly confident the rear O2's were the culprit when the front ones didn't solve it. Evidently the rears help calibrate the front ones so it made sense in my head since the STFT and O2 readings are all over the place but that didn't fix it.

The car also has:

-Index 12 injectors
-New HPFP
-Fuel it stage 3 lpfp
-Motiv PI kit

It's driving me nuts to the point I don't even like driving the car anymore. Please help!

[whyzee125]

Data log from today while vehicle was stopped but being held at ~1750 RPMs

https://datazap.me/u/whyzee125/oscil...18-19-20-21-22

Interesting, my lambda's look better after the new sensors but the STFT's and RPM's are still going nuts. What's the dealio?

[Saif2018]

Originally Posted by whyzee125

Data log from today while vehicle was stopped but being held at ~1750 RPMs

https://datazap.me/u/whyzee125/oscil...18-19-20-21-22

Interesting, my lambda's look better after the new sensors but the STFT's and RPM's are still going nuts. What's the dealio?

Stopped in neutral with 5% throttle?

I'm looking at it on my phone but all I see is about 100rpm difference between peaks and troughs, what makes you think its going nuts?

Do you get the rpm oscillations when you are cruising ay steady throttle or WOT?

[whyzee125]

Originally Posted by Saif2018

Stopped in neutral with 5% throttle?

I'm looking at it on my phone but all I see is about 100rpm difference between peaks and troughs, what makes you think its going nuts?

Do you get the rpm oscillations when you are cruising ay steady throttle or WOT?

Yes, very noticeable with the cruise control on or off. WOT is fine however.

I did the still one to make sure I wasn't accidentally varying the throttle from bumps on the road, etc.

[Bimmer_Bro]

Originally Posted by whyzee125

Yes, very noticeable with the cruise control on or off. WOT is fine however.

I did the still one to make sure I wasn't accidentally varying the throttle from bumps on the road, etc.

Makes me wonder if it's the throttle pedal itself? Or maybe the throttle body since they are both electronic.

[whyzee125]

Here is a log while cruising. Sorry, I couldn't keep the pedal 100% steady but you can still see the oscillation.