[claytonap1]

Originally Posted by Robs335iproblems

I disconnected the MAF and there was no change in the surging. I cleaned the MAP in the charge pipe and the T-MAP in the intake and there was no change. Checked for leaks with starter fluid and nothing. The car is buttery smooth when idling, so I'm thinking that vacuum is not the issue. When the car is cold (in the morning as opposed to after it's been driven and restarted), it runs fine (no surging). So it made me think it has to be related to something warming up, or waiting until the car get's into closed loop. So I started really thinking about the whole combustion process and began searching forums outside of BMW. There are literally hundreds of surging posts. Based on all of that thinking and reading, I'm going to disconnect the upstream 02 sensor, force the car into open loop and see if that works. Since the unplugged MAF (and air intake) didn't have any change, the 02 sensor is next in my thinking. After that, the only things left would be fuel and spark, which I don't think it's either one. Rail pressure if fine and there are no codes for misfires, so I don't think it's spark/coil related. While not BMW's, there are countless other posts regarding surging, bucking, etc. and many have ended up with upstream 02 sensor problems, even when there wasn't a CEL or otherwise. So that's next on my list. The thinking is that under light acceleration, the 02 sensor is reading, but the readings are slow, therefore it's basically trying to make late adjustments to air/fuel and then when they change, it's late to make the next adjustment, and does overshoots one way and then the other, which is why it begins what feels like an oscillating throttle. When reading properly the sensors usually adjust in milliseconds, so you'd never actually feel when it's doing what it's supposed to do. Somehow, the normal lambda oscillating readings are being driven back into the DME improperly and the car is trying to adjust air/fuel. The 02 sensors are the only sensor readings that actually oscillate as part of their normal operation as opposed to sensors that take readings (temp, pressure, air flow). If they are slow to respond, then it might be causing the issue while at the same time, not necessarily generating a code.

Rob, mine happens all the time, whether its cold or warmed up.

[Robs335iproblems]

Update. I think the O2 sensor isn't the issue. I've had it unplugged for the past few days and while I think it might be better, I can get it to do surge under the same general conditions. I know I'm running with no sensor at all, however, I figured if it ran fine open loop, then it might point to something. I did reset a bunch of adaptations (lambda, throttle, load, etc.) prior to unplugging the sensor to ensure I was dealing with a 'fresh' DME, but seems as if that didn't matter. I can't believe this problem. It's absolutely insane that a 60k car has this kind of issue. I do have a new O2 sensor on the way, so I'll replace and report back, however, I'm not hopeful. Since the car didn't do it when it was newer and over time it started happening and actually has gotten worse to where it is now, it has to be sensor related. Seems unlikely that it's a DME or programming issue (especially since I had the dealer reprogram the car a few weeks ago). I'll try and log mine so it's available for anyone to view. One way or another, I'm going to figure this out.

[Robs335iproblems]

Update and potential solution...

I pulled the MAP in the charge pipe and the car drove like junk, so I know that's not the problem.

Going back to the o2 sensor. The car drove much better with the sensor unplugged, but not perfectly. I put in a new sensor and it was back to poor driving.

I did have a BMW intake that I took off and went back to stock but I still had the aftermarket DP installed (Active Autoworks High Flow Catted downpipe). Figuring that I had to put the car back to stock before taking it to the dealer, I pulled the downpipe and noticed that the gasket between the downpipe and turbo wasn't fully sealed. The metal gasket was crushed on one side and was not on the other. The side that wasn't crushed/sealed, had dark blow-by gas marks. I think the poor seal at the exhaust point, which is essentially before the O2 sensor, was causing the sensor to act erratically.

I'll be driving the car tomorrow to work and we'll see if it's better. If so, that certainly points to a potential solution, being an exhaust leak before the 02 sensor. While there may be people that are still completely stock, the v-band clamp that connects the downpipe to the turbo may be loose. That would cause the same issues.

I'll post findings tomorrow.

[claytonap1]

Originally Posted by Robs335iproblems

Update and potential solution...

I pulled the MAP in the charge pipe and the car drove like junk, so I know that's not the problem.

Going back to the o2 sensor. The car drove much better with the sensor unplugged, but not perfectly. I put in a new sensor and it was back to poor driving.

I did have a BMW intake that I took off and went back to stock but I still had the aftermarket DP installed (Active Autoworks High Flow Catted downpipe). Figuring that I had to put the car back to stock before taking it to the dealer, I pulled the downpipe and noticed that the gasket between the downpipe and turbo wasn't fully sealed. The metal gasket was crushed on one side and was not on the other. The side that wasn't crushed/sealed, had dark blow-by gas marks. I think the poor seal at the exhaust point, which is essentially before the O2 sensor, was causing the sensor to act erratically.

I'll be driving the car tomorrow to work and we'll see if it's better. If so, that certainly points to a potential solution, being an exhaust leak before the 02 sensor. While there may be people that are still completely stock, the v-band clamp that connects the downpipe to the turbo may be loose. That would cause the same issues.

I'll post findings tomorrow.

definitely let me know if this fixes it. Trying to get it fixed so i can trade the car in for an M.

[Robs335iproblems]

Not sure I've seen any improvements, however, the gasket was an issue and I had to eliminate the possibility that the DP was the issue.

In the latest move, I've been retrofitting ACC into the car, so I needed to code the eBay DSC module in ESYS, so I figured, why not, I coded both the DME and TCU to the car's VO.

I'll say that in the one hour of drive time today, the car drove better than it has in a long time. Started smoothly from a dead stop and drove great (starting from a light or stop sigh had been choppy also). I don't know whether or not encoding the ECU's back to the VO essentially erased any old superfluous data, reset adaptations or whatever, but for now, the car is driving great. For me, the surging always comes back, even when I reset the adaptations, typically in short order, so I'll be curious to see if this does the trick. I'll be on the road tomorrow for at least 2-3 hours, so if it doesn't come back, then I'll say I've found the solution.

[Wires]

Originally Posted by Robs335iproblems

Update and potential solution...

I pulled the MAP in the charge pipe and the car drove like junk, so I know that's not the problem.

Going back to the o2 sensor. The car drove much better with the sensor unplugged, but not perfectly. I put in a new sensor and it was back to poor driving.

I did have a BMW intake that I took off and went back to stock but I still had the aftermarket DP installed (Active Autoworks High Flow Catted downpipe). Figuring that I had to put the car back to stock before taking it to the dealer, I pulled the downpipe and noticed that the gasket between the downpipe and turbo wasn't fully sealed. The metal gasket was crushed on one side and was not on the other. The side that wasn't crushed/sealed, had dark blow-by gas marks. I think the poor seal at the exhaust point, which is essentially before the O2 sensor, was causing the sensor to act erratically.

I'll be driving the car tomorrow to work and we'll see if it's better. If so, that certainly points to a potential solution, being an exhaust leak before the 02 sensor. While there may be people that are still completely stock, the v-band clamp that connects the downpipe to the turbo may be loose. That would cause the same issues.

I'll post findings tomorrow.

Have you put the OEM intake back on and driven for a long while? You're blaming the car, but it could be the intake and now the fuel trims are all out of wack. They take longer than a couple quick drives to return to normal.

[Robs335iproblems]

I think this is finally the problem/solution!

Yep, stock intake and stock DP have been back on the car for a few hundred miles.

There's nothing that I've done to the car that has had any changes in behavior. Also LTFT was reading -.1 and STFT ran in a range between -2 to +2, so they seem to be reasonable and the fuel trim adaptations were reset a while ago.

So today, I started reviewing and logging every value that I could while driving around. Everything looked good until I got to the Intake VANOS. That's where things started to go off the rails.

I looked at both the required and actual exhaust VANOS angle and intake VANOS angle. I did this under heavy acceleration, coasting and light acceleration. The required angle and actual angle on the exhaust were nearly identical. Maybe a degree or two off as I was accelerating, etc. however, when coasting, they were spot on.

But not the Intake VANOS. I found that the intake VANOS was jumping/cycling all over the place anywhere from 10-15 degrees above and then below the required angle. Even when I was coasting. I could watch the intake angle drop, then increase then drop, in a very rhythmic cycle. Except under very hard acceleration, it constantly bounced up and down. And, when I started driving with very light acceleration, I could feel the surges corresponding in exact timing with the higher/lower spikes in the VANOS angle. All of the other graphs made sense. Throttle was steady but RPM, Load and Lambda all began to bounce in the same rhythm as the VANOS. Thinking that the VANOS is a solenoid and/or spring set up, it might make sense that it's going bad and the car is continually trying to get actual values to match the required value and in doing so, it undershoots, then over shoots over and over.

I've read on other forums that the VANOS has been suggested as a root cause, but that was on N54/N55 forums. Although this solenoid is a different design, it's having the same effect. Odd that there are no codes, but maybe it just hasn't gotten that bad yet. I tried the VANOS test in ISTA for the intake solenoid and the first time, it 'passed' but I could see the values were technically outside the allowed +/- 5 degrees. I then did the exhaust and it hit the values all within +/- 1 degrees. I then went back to do the intake again and this time, it failed. I got an 'Adjustment is too slow or the setpoint value cannot be reached'. Bingo, Intake VANOS Solenoid issue!

Problem is, the B58, with the timing chain against the firewall, has the VANOS solenoids also against the firewall. Not easy to get too like the old ones, so that's going to be a PITA to swap out, but now I'm convinced that's the issue.

I will also say that this has happened over time. It wasn't a one day it didn't surge and the next day it did, so clearly it was something that got worse over time. I have a 435 with an N55 with all sorts of mods, similar to this one, so I didn't think it could be an intake or DP or tune as it simply didn't make sense that the car would behave so poorly with those very basic mods.

[Robs335iproblems]

SOLVED!!!!!!!!!!!!!! SOLVED!!!!!!!!!!!!!!!!!!!! SOLVED!!!!!!!!!!!!!!!!

The issue did come down to the intake VANOS Actuator. P/N 11367614288 A stupid $61 part was the culprit behind all of this hideous driving.

A few things I learned...

1. No codes. That's what makes it so hard to find. And when I ran ISTA, the first time, it passed. If you take it to a dealer, they'll probably see the same thing which is why they can't offer a solution.
2. They seem to die slowly. This did not happen overnight. It was a long slow progression over the last 6-8 months when I first felt like the car surged until now, when it was nearly undrivable.
3. They are easy to replace. Don't listen to any other post regarding B58 engines needing to be dropped to get to the actuator. It's not any harder than replacing spark plugs. You'll need to remove the cross bar brace and cowling, but it's only a handful of bolts. No special tools needed. Watch the video and about half way though, he explains how to get to the actuator.

4. They are probably going to fail often, which is why a lot of people report having the surging issue. My dealer had 4 in stock and the part's guy said, yeah, we have a bunch so they do go bad.
5. It's amazing how poorly the car drove. Since it happens over time, you can't feel had badly it's gotten until it's replaced. Now that it's fixed, I can't believe how smoothly it drives.
6. This is only a fix for the surging at mid level RPM. I will say that sometimes, when it was bad, even starting out I'd feel a surge, but mainly, it was felt during the mid-level RPM driving. There is a SIB (recall) for DME reprograming, which is intended to fix some minor drivability issues. Make sure you have that done first and then attack the actuator.
7. This only applies to B58. The VANOS system for the N series engines is different. While a VANOS may fix those issues, this problem seems to be only on B58 with the actuator being the fix.
8. I think the intake is where the problem lies. I doubt the exhaust would have the same result, so focus on the intake actuator.

Hopefully this gives people hope. Even if you take it to a dealer, insist they replace the actuator, or do it on your own.

Now I can put my BMS intake back on, install my DP and bench unlock my DME so I can retune the car. All I care is that it's back and it feels great.

[Wires]

Very cool, thanks for the update. The VANOS would be changing engine flows which would explain your issues. "Problem" is until it went really bad (I don't even know if you'd get a code for that unless it flat out failed), it becomes more of just the issues you experienced.

Putting this info in the back of the mind for later use....

[b58boi]

Originally Posted by Robs335iproblems

SOLVED!!!!!!!!!!!!!! SOLVED!!!!!!!!!!!!!!!!!!!! SOLVED!!!!!!!!!!!!!!!!

The issue did come down to the intake VANOS Actuator. P/N 11367614288 A stupid $61 part was the culprit behind all of this hideous driving.

A few things I learned...

1. No codes. That's what makes it so hard to find. And when I ran ISTA, the first time, it passed. If you take it to a dealer, they'll probably see the same thing which is why they can't offer a solution.
2. They seem to die slowly. This did not happen overnight. It was a long slow progression over the last 6-8 months when I first felt like the car surged until now, when it was nearly undrivable.
3. They are easy to replace. Don't listen to any other post regarding B58 engines needing to be dropped to get to the actuator. It's not any harder than replacing spark plugs. You'll need to remove the cross bar brace and cowling, but it's only a handful of bolts. No special tools needed. Watch the video and about half way though, he explains how to get to the actuator.

4. They are probably going to fail often, which is why a lot of people report having the surging issue. My dealer had 4 in stock and the part's guy said, yeah, we have a bunch so they do go bad.
5. It's amazing how poorly the car drove. Since it happens over time, you can't feel had badly it's gotten until it's replaced. Now that it's fixed, I can't believe how smoothly it drives.
6. This is only a fix for the surging at mid level RPM. I will say that sometimes, when it was bad, even starting out I'd feel a surge, but mainly, it was felt during the mid-level RPM driving. There is a SIB (recall) for DME reprograming, which is intended to fix some minor drivability issues. Make sure you have that done first and then attack the actuator.
7. This only applies to B58. The VANOS system for the N series engines is different. While a VANOS may fix those issues, this problem seems to be only on B58 with the actuator being the fix.
8. I think the intake is where the problem lies. I doubt the exhaust would have the same result, so focus on the intake actuator.

Hopefully this gives people hope. Even if you take it to a dealer, insist they replace the actuator, or do it on your own.

Now I can put my BMS intake back on, install my DP and bench unlock my DME so I can retune the car. All I care is that it's back and it feels great.

I’m glad you found a possible solution!!! I’ve been fighting and struggling with this for a good year and a half now. Been contemplating just selling the car but hasn’t been that egregious of an issue to do that just yet. I replaced a bunch of parts with no avail. The no CEL part really boggled me since these cars have so many sensors and computers I was just waiting for something to tell me something was wrong or broken. Glad you dug into it. I will replace that intake actuator and report back to see if it solves my issue as well. Appreciate guys like you!!!

[D's Bimmer]

Originally Posted by b58boi

I’m glad you found a possible solution!!! I’ve been fighting and struggling with this for a good year and a half now. Been contemplating just selling the car but hasn’t been that egregious of an issue to do that just yet. I replaced a bunch of parts with no avail. The no CEL part really boggled me since these cars have so many sensors and computers I was just waiting for something to tell me something was wrong or broken. Glad you dug into it. I will replace that intake actuator and report back to see if it solves my issue as well. Appreciate guys like you!!!

Originally Posted by b58boi

I'm glad you found a possible solution!!! I've been fighting and struggling with this for a good year and a half now. Been contemplating just selling the car but hasn't been that egregious of an issue to do that just yet. I replaced a bunch of parts with no avail. The no CEL part really boggled me since these cars have so many sensors and computers I was just waiting for something to tell me something was wrong or broken. Glad you dug into it. I will replace that intake actuator and report back to see if it solves my issue as well. Appreciate guys like you!!!

I too have been struggling with this issue since last summer. Replaced plugs, coils, injectors.

Have no codes.

Have found a problem with my wiring harness and the clip that reads my rear O2 sensor is broken.

Will replace the intake solenoid while doing the wiring harness and clip.

My logs show my Lambda Actual bouncing all over the place with Throttle Closure.

https://datazap.me/u/diggler70/log-1...=0&data=11


Fingers crossed.

[claytonap1]

i replaced both pre and post cat 02 sensors and it fixed the issue. Car runs great now. We also reset adaptations.

[b58boi]

Originally Posted by D's Bimmer

I too have been struggling with this issue since last summer. Replaced plugs, coils, injectors.

Have no codes.

Have found a problem with my wiring harness and the clip that reads my rear O2 sensor is broken.

Will replace the intake solenoid while doing the wiring harness and clip.

My logs show my Lambda Actual bouncing all over the place with Throttle Closure.

https://datazap.me/u/diggler70/log-1...?log=0&data=11


Fingers crossed.

Please do let us know what happens!!! I’m holding off on doing anything more until I can be more certain of the source

[b58boi]

Originally Posted by claytonap1

i replaced both pre and post cat 02 sensors and it fixed the issue. Car runs great now. We also reset adaptations.

Did you have any codes? I would think if 02 sensors went out that CEL would light up real fast

[claytonap1]

as with others who have experienced this same issue, no codes were thrown. I was in the same boat as many others, car ran like this for months. Changed coils, spark plugs, reset adaptations. I even replaced the VANOS actuators. Problem was still there. Until one day i was on facebook and someone w/the exact issue had his car diagnosed and saw that it was the lambda sensors. I replaced both and car is back to running like new. The sensors are cheap, i bought the pre 02 sensor from trodo.com and the post 02 sensor off of ebay.

[mevans313]

Originally Posted by Robs335iproblems

SOLVED!!!!!!!!!!!!!! SOLVED!!!!!!!!!!!!!!!!!!!! SOLVED!!!!!!!!!!!!!!!!

The issue did come down to the intake VANOS Actuator. P/N 11367614288 A stupid $61 part was the culprit behind all of this hideous driving.

A few things I learned...

1. No codes. That's what makes it so hard to find. And when I ran ISTA, the first time, it passed. If you take it to a dealer, they'll probably see the same thing which is why they can't offer a solution.
2. They seem to die slowly. This did not happen overnight. It was a long slow progression over the last 6-8 months when I first felt like the car surged until now, when it was nearly undrivable.
3. They are easy to replace. Don't listen to any other post regarding B58 engines needing to be dropped to get to the actuator. It's not any harder than replacing spark plugs. You'll need to remove the cross bar brace and cowling, but it's only a handful of bolts. No special tools needed. Watch the video and about half way though, he explains how to get to the actuator.

4. They are probably going to fail often, which is why a lot of people report having the surging issue. My dealer had 4 in stock and the part's guy said, yeah, we have a bunch so they do go bad.
5. It's amazing how poorly the car drove. Since it happens over time, you can't feel had badly it's gotten until it's replaced. Now that it's fixed, I can't believe how smoothly it drives.
6. This is only a fix for the surging at mid level RPM. I will say that sometimes, when it was bad, even starting out I'd feel a surge, but mainly, it was felt during the mid-level RPM driving. There is a SIB (recall) for DME reprograming, which is intended to fix some minor drivability issues. Make sure you have that done first and then attack the actuator.
7. This only applies to B58. The VANOS system for the N series engines is different. While a VANOS may fix those issues, this problem seems to be only on B58 with the actuator being the fix.
8. I think the intake is where the problem lies. I doubt the exhaust would have the same result, so focus on the intake actuator.

Hopefully this gives people hope. Even if you take it to a dealer, insist they replace the actuator, or do it on your own.

Now I can put my BMS intake back on, install my DP and bench unlock my DME so I can retune the car. All I care is that it's back and it feels great.

I had the exact symptoms you’ve described, I did some data logging and my exhaust VANOS was all over the place. That’s definitely my issue. I’ll be making a video specifically dedicated to this issue replacing the actuator very soon and I’ll post the link here when I complete it. Thanks!

[ErikB]

Originally Posted by Robs335iproblems

SOLVED!!!!!!!!!!!!!! SOLVED!!!!!!!!!!!!!!!!!!!! SOLVED!!!!!!!!!!!!!!!!

The issue did come down to the intake VANOS Actuator. P/N 11367614288 A stupid $61 part was the culprit behind all of this hideous driving.

Thank you for this info, i am experiencing the exact same thing. I received my new actuator yesterday and will install it this weekend. I dont have a log as I am stock, but if its not the intake side, I will swap the used intake one to the exhaust.


I will p[ost if it worked for me as well

[ErikB]

just wanted to add that this completely cleared up my issues as well. I appreciate the troubleshooting on this guy's, thanks

[VVlasy]

Thanks for the tip. As the original poster, many years later. I can also confirm this a fix for the bucking issue but other drivability issues too. I will update the main post.

I replaced both of the actuators. It solved the bucking, but also rough 1-2 shift on cold start. Hard shifts on sport+ (kinda miss those tbh but can be solved by xHD tune, which I originally bought solve some issues). Hard downshifts, especially 1 and 2. Jerking when applying and releasing throttle, especially noticeable when the torque converter wasn't locked, stop and go traffic was really a chore. I actually thought I had an issue with the transmission, but the actuators were the cause all along.

Thanks Robs335iproblems

A few tips for removing, as for me I didn't feel it was that easy.

Get a short stubby flathead screwdriver (seen in video from mevans313 ) I had a friend lend me one he has from his dad, probably 30 years old, but for getting out the passenger side actuator is almost impossible without this.

When you get the actuator turned about a inch-two inches, and it wont go anymore with your hand or the screw driver. Try to pry it off a bit and then keep turning, it will release real easy that way. it took me half an hour to realize this.

Also be careful not to drop those metal clips that face downwards. Its a real PITA to get back in. Nigh impossible if you have bigger sized hands.

[VVlasy]

Originally Posted by ErikB

just wanted to add that this completely cleared up my issues as well. I appreciate the troubleshooting on this guy's, thanks

Which one was the problem for you? Intake or exhaust? I still recommend replacing both... If you replace one, the other will give in some time later as well.

[JoHnMuir]

Originally Posted by VVlasy

Thanks for the tip. As the original poster, many years later. I can also confirm this a fix for the bucking issue but other drivability issues too. I will update the main post.

I replaced both of the actuators. It solved the bucking, but also rough 1-2 shift on cold start. Hard shifts on sport+ (kinda miss those tbh but can be solved by xHD tune, which I originally bought solve some issues). Hard downshifts, especially 1 and 2. Jerking when applying and releasing throttle, especially noticeable when the torque converter wasn't locked, stop and go traffic was really a chore. I actually thought I had an issue with the transmission, but the actuators were the cause all along.

Thanks Robs335iproblems

A few tips for removing, as for me I didn't feel it was that easy.

Get a short stubby flathead screwdriver (seen in video from mevans313 ) I had a friend lend me one he has from his dad, probably 30 years old, but for getting out the passenger side actuator is almost impossible without this.

When you get the actuator turned about a inch-two inches, and it wont go anymore with your hand or the screw driver. Try to pry it off a bit and then keep turning, it will release real easy that way. it took me half an hour to realize this.

Also be careful not to drop those metal clips that face downwards. Its a real PITA to get back in. Nigh impossible if you have bigger sized hands.

I've been having all those problems, somewhat intermittently, and suspected a VANOS issue. Good to hear that this is one possible cause.

[ErikB]

Originally Posted by VVlasy

Which one was the problem for you? Intake or exhaust? I still recommend replacing both... If you replace one, the other will give in some time later as well.

intake, but i am ordering another for exh. just wanted to test 1 first :-)