[e90yyc]

Originally Posted by stickle1212

I had the 330 flash for a few months but I couldn't tell if it was actually doing anything so I reflashed it 2 weeks ago. I did see that ecu error but I thought it was one of those expected errors when you do a flash so I didn't share that. I use IMPA and Blue Driver which actually does give BMW codes. I doubt it's the fuel pump but I will get one from the junkyard just to test instead of spending $500 and that's not the issue.

Sorry, @nsjames, what exactly is the "OP"?

I would be shocked if this had anything to do with your 330 flash. I wouldn’t worry about that, but if for some reason you’re concerned or just want to rule out unequivocally the possibility that software is to blame, by all means flash back to stock.

OP means Original Poster, i.e., you.

Okay, so here are a number of recommendations. Take some, all, or none. I’m just trying to help you avoid shotgunning parts at your car or wasting your time pulling junkyard parts unless there’s a good reason to.

1. Please, drain your TC and fill it with the correct fluid. I know this might not be the issue, but you’ll need to do this anyway. Just do it now to ensure proper function of your TC throughout the troubleshooting process.
2. Post a comprehensive list of all the codes they pulled at the dealer. (On a side note, I still don’t understand how they pulled so many codes yet you were only seeing VTG Oil Wear?)
3. Clear all your codes, take that fly whip for a rip, and see what codes actually come back. I guarantee you that some of those codes were set when you flashed or coded your car, and assuming all is well with software/coding, won’t return once cleared.
4. Don’t touch or swap your fuel pump. If you really think this is a fuel delivery issue, there are other diagnostics to perform before going down this road.

On one hand if you’re swapping in a 3IM, flashing your modules, and changing your TC fluid, it makes me think you have a decent understanding of your car. On the other hand, when you’re asking whether marvinstockman was referring to the “RPM gauge” when he said “tach,” putting regular gear oil into your TC, and forgetting to include important details in your explanation of what your problem is, it raises doubts. I don’t mean to be rude, I’m just saying this because it would be prudent to follow the advice of people like nsjames who have a solid understanding of this vehicle. It sounds like you’ve kinda gone off on your own, and while you’re perfectly within your right to do that, it just might end up being a more expensive, longer path than being methodical in your approach to this, which I think people here can help you with.

Because the N52 doesn’t have a built-in fuel pressure sensor, you’ll have to connect a gauge to the fuel rail to test pressure. This is not something I’ve ever had to do so unfortunately I don’t have any useful advice. BUT, an ailing fuel pump doesn’t feel like you’re getting rear-ended or are hitting a wall; it feels like you’re losing power but not in a “violent” way.

Unfortunately it sounds like the dealership was a waste of time and money, and while I wish that wasn’t the case, I’m not surprised. Dealers use ISTA which basically tells them the “standard” action to take based on a particular DTC. It also tells them what order to perform their diagnostic tasks in. Because you sent your car to them with what appear to be a bunch of old codes (sorry—I tried but couldn’t quite see what mileage was at time of drop-off so I could be wrong), this tech is wasting his time investigating codes that likely have nothing to do with your issue. I’ve had “No Coding” errors on many occasions and might actually have one now, and I can tell you it is not the source of your issue.

Anyway, keep us posted.

[eljay]

Fuel cut would have to be pretty extreme to almost lock-up the engine as you're describing. That rpm drop seems too quick for fuel starvation. You would feel the car wanting to stall first.
The 330i flash should be fine and not related.

As others said:
- put the correct fluid into the transfer case and ensure you perform the transfer case reset procedure using ISTA
- re-trace your steps in case you unplugged something.


You mentioned that this happens when you stab the throttle, so there's some G-force generated, which may move a loose plug or wire and when you ease off it "rocks" back into place and electrical path is resumed. Just my theory.

From that dealer scan, you seem to have some sensor and power supply issues and I bet that is causing the electrical mayhem and causing a communication issue with DME under some of the conditions. Without proper DME connections, the engine just cuts out completely and the drop on the needle would indicate electrical issues as well.
If you look at the codes, you have issues happening on the passenger side:
- mirror heating on passenger side.
- AUC sensor (also on passenger side on the cowl)
- Junction Box terminal supply issue (also on passenger side)
- side marker (right side again)
And then issues communicating with dashboard, headunit, and steering angle sensor.

As the tech points out, DME cover is loose, so there may have been water ingress, or whoever was messing with the box and connectors, didn't plug something back in properly. I would check all the connections there. Then look around/behind the fuse box in the glovebox for any signs of water ingress. You can also look through the openings behind the cabin filter down where you see the blower motor and check for anything that doesn't look right there.

[marvinstockman]

If you can't measure fuel pressure while driving, you can measure air-fuel-ratio while driving with a cheap OBD scanner. Anything above 14.7 means your going lean and not getting the fuel you need.

[stickle1212]

Thank you all for your input. Due to work, I wasn't able to dig too deeply today. However, I was able to put to rest my mechanic's theory of the fuel pump being the issue. I swapped my pump and sending unit from a 2011 328! ($45) I must say for the first 20 minutes I was elated because the symptoms didn't show up. Unfortunately, that good feeling wasn't meant to last. I wish I had a competent mechanic that I could pay to fix the issue.

Observations:
* When the car is cold the symptoms don't show up for the first few times I floor the pedal.
* When I accelerate at a moderate rate, the vehicle drives fine.


Tomorrow I'll be:
* replacing the transfer case fluid and double-checking the electrical connector.
* Inspect the connectors to the DME, 02 sensor, and ground locations.
* Inspect the fuse box area for water damage.

Latest error messages:
https://hosting.photobucket.com/imag...=278&crop=fill

https://hosting.photobucket.com/imag...=278&crop=fill

Thanks for your continuing help.......

[Brian86]

That has to be some sort of bizarre electrical gremlin (yea... I know, not helpful). BUS communication problem or some module losing power. But why on earth would that correspond with acceleration?

There is no way a car with a manual gearbox has the actual engine RPM are dropping from 2,500 to 1,000 and back up in half a second. Not unless the rear wheels are momentarily locking.

[stickle1212]

I agree....My hunch is it has something to do with the transfer case. The vehicle doesn't feel like braking which usually pushes you forward, it's quite the opposite. It feels like something is pulling the vehicle behind. At times the 4x4 light will come on when it occurs and stay on until the engine is restarted.

[Brian86]

Try dropping the front driveshaft to see if the problem persists?

You need to get the incorrect fluid out of the T-case. There is multi-plate wet clutch in there that is constantly slipping. It's very sensitive to the friction characteristics of the oil.

Anybody think it's possible that the T-case clutch is actually 'locking'? The front and rear axle have ever so slightly different gear ratios, so if the clutch were ever to actually 'fully lock' it would bind the drivetrain and cause one of the four wheels to start slipping. Like a truck trying to parallel park on pavement in 4-low. One of the wheels starts hopping.

Perhaps the computer sees a wheel speed sensor decrease speed and it panics? Throttle (or spark/fuel) cut combined with bound up driveline causes the buck until a split second later the car releases the T-case clutch. It happens on acceleration because the ECU engages the front axle when putting down power?

Still doesn't explain the tach needle spiking down... unless that is just a side effect of the ecu doing some sort of 'panic shutdown routine' because it sees a wheel speed condition that shouldn't be possible.

This is pure speculation of course.

[marvinstockman]

Once more with feeling, try monitoring fuel pressure of AFR while driving. If fuel pressure drops or AFR goes up, you have a fuel restriction/supply problem.

[e90yyc]

Brian86 I think it’s possible this has to do with TC. When the fluid starts to wear excessively and the friction modifiers are no longer working well, you’ll start to get a surging/binding feeling when accelerating around corners. Until the correct fluid is in that TC, speculating as to what else it might be is kind of pointless. Especially when OP sometimes gets a 4x4 warning light when this happens.

I agree the rest of the symptoms seem odd. But hey—this is a BMW .

[stickle1212]

Thank you all for your input. As it turns out changing the fluid did fix the issue!!! Brian's assessment seems to be spot on. I think I complicated the issue a bit by not changing the fluid at first as @e90yyc had suggested. It's really amazing that the wrong fluid could cause such erratic behavior. I feel really lucky that it didn't result in permanent damage to the transfer case. On a second note, changing my fuel pump and sender ($45) did fix an old issue where my tank would show 3/4 when it was full.


Is there a specific version of INSTA to use for the reset procedure? I currently have IMPA but it doesn't have the feature to do the calibration.

Thank you one and all, I really appreciate all the help!!!

[Brian86]

It'd be a good idea to change the fluid again in a few hundred miles to get as much of the remaining bad stuff out. One change probably only removes 95-ish% of the old fluid.

[e90yyc]

Edit: NVM. Looks like fluid change didn’t solve it…

[nsjames]

that's incredibly odd and not at all what i expected.

[stickle1212]

Update.....
Yesterday I used my friend's Snap On to register the new oil change and do the required calibration, immediately after, the problem returned....

[nsjames]

well on the one hand I like not being wrong.
on the other, that's a bummer.

I still think you need to investigate all the wiring first, and then datalog it while driving to figure out what happens in the DME.

[eljay]

Sorry to hear that you are still battling this.
As I mentioned above, and others did as well, there's something electrical going on. The fact that the behaviour seems "temperature and g-force sensitive" would also hint at some wiring or connector issue.
Logging issues while running the car would help greatly to narrow down the areas to investigate, but the codes from the dealer give you a good start.

[stickle1212]

Any suggestions on what to use for the data log?

[e90yyc]

Originally Posted by stickle1212

Any suggestions on what to use for the data log?

Oh no!

I am just as curious as you are what to use for data logging. That’s been the single biggest impediment to troubleshooting my issue. The 335 guys have a ton of options, but as far as I know we have basically nothing.

I’ve installed TestO, and while it works, I haven’t been able to log what I want.

Just out of curiosity, if you turn off DSC (long press button), does the issue still occur?

[nsjames]

a bimmer geeks cable, inpa and testo for me.

[e90yyc]

Originally Posted by nsjames

a bimmer geeks cable, inpa and testo for me.

Can you log wheel speed sensors with TestO though?

[nsjames]

never tried

[Tambohamilton]

I'm 99% that's not a fuel issue. It's electrical. Even if I switched off my engine while driving, the rpm wouldn't drop that quickly; no chance.

We need a list of codes that return after being cleared.

On the car I'd start by checking wiring, but that'll be a very drawn out process without codes to focus your search.