[torrque]

From documentation I have from German Autosports, it seems that problem started after injectors installation... They must have f**d up some wiring or the like, or as one said here, it could be Ebay injectors ? Is there a way to tell if you look at it if they are OEM or not?

There are no "generic" or "3rd party" injectors made for this platform. The box they come in might be different, but they're all the same $hit.

Only way to tell whether or not you have an issue with one or all of them is to pull them and:
1. check the status/condition of the injector tip/seal
2. check to make sure all decoupling elements are in place
3. check to make sure that all cables are going to the right injector
4. Etc.

What are your voltage readings?
- battery with car off
- battery with car on
- alternator with car on
- voltage while at idle
- voltage while driving
- etc.

If you don't have one already, you can use something like this:
https://smile.amazon.com/Charger-Dis...+voltage+meter

[torrque]

Originally Posted by FCobra94

There are no "generic" or "3rd party" injectors made for this platform. The box they come in might be different, but they're all the same $hit.

Only way to tell whether or not you have an issue with one or all of them is to pull them and:
1. check the status/condition of the injector tip/seal
2. check to make sure all decoupling elements are in place
3. check to make sure that all cables are going to the right injector
4. Etc.

What are your voltage readings?
- battery with car off
- battery with car on
- alternator with car on
- voltage while at idle
- voltage while driving
- etc.

If you don't have one already, you can use something like this:
https://smile.amazon.com/Charger-Dis...+voltage+meter

I have uploaded the log I have, voltage seems fine, just over 14 when running and above 12 when shutdown. It was 11 when I started the car again.... check it out and thanks!

[langsbr]

Do you have MHD for logging? Or some way to do logging? Mine has a stuttering/bucking issue due to an O2 that's acting up.

Go for a drive while logging and monitor the AFRs for both banks and the STFT for both. Mine is going nuts and the STFT for bank 2 is adding the max when the O2 quits responding and gets stuck at 14.93. Even if I add throttle which would have it richen up, it never moves. if you let off in gear, the o2s should go to 239:1 or at least 20:1.

It sounds for sure like a fueling issue - the key is figuring out why the computer thinks it needs more fuel when it doesn't.

[autoart]

If the problem started after the fuel injectors, I would start there. Are the injectors in correctly with coupling and metal plate.
I have read that if their not in correctly the injector hole can get enlarged.

[torrque]

Air mass Fuel PumpPWM DME Battery O2 Throttle

75.96209 47.949219 4.042969 14.320312 250 1.867301
70.536232 48.622131 4.042969 14.523437 250 1.867301
70.536232 48.254395 4.042969 14.523437 250 1.867301
184.47937 99.000549 4.042969 12.187499 255 0
75.96209 99.000549 4.042969 11.984374 255 1.867301
108.517273 49.452209 4.042969 11.984374 255 3.734603
352.681152 51.313782 4.042969 12.390624 255 13.07111


So I am convinced now that it is electrical issue 100%. See in table above how battery voltage drops to under 12; this is when the bucking happened. It happened twice in this logging session (driving around the block), and fuel pump request is at maximum at that time. O2 is oxygen sensor, not sure what value is that one..
Should I look at the low pressure fuel pump again, but that was changed ...The other thing is , that , the warmer the engine gets, the more pronounced, to the stage that it stalls.

[torrque]

Originally Posted by autoart

If the problem started after the fuel injectors, I would start there. Are the injectors in correctly with coupling and metal plate.
I have read that if their not in correctly the injector hole can get enlarged.

Yep, had a very close look, coupling thing is in place on all of them; took the bracket off. Injectors will give you misfire codes though, which I don't have... and they are new injectors, ending in -12 all of them, programmed ok.

[torrque]

Originally Posted by langsbr

Do you have MHD for logging? Or some way to do logging? Mine has a stuttering/bucking issue due to an O2 that's acting up.

Go for a drive while logging and monitor the AFRs for both banks and the STFT for both. Mine is going nuts and the STFT for bank 2 is adding the max when the O2 quits responding and gets stuck at 14.93. Even if I add throttle which would have it richen up, it never moves. if you let off in gear, the o2s should go to 239:1 or at least 20:1.

It sounds for sure like a fueling issue - the key is figuring out why the computer thinks it needs more fuel when it doesn't.

what is STFT? Thanks.

Originally Posted by torrque

So I am convinced now that it is electrical issue 100%.

Of course it is...the hard part is figuring out where and how though.

I say remove the DME again and make sure every pin/harness is put back into place correctly.

After that, it'll probably be best to trace wiring to/from the unit itself.

[torrque]

Originally Posted by FCobra94

Of course it is...the hard part is figuring out where and how though.

I say remove the DME again and make sure every pin/harness is put back into place correctly.

After that, it'll probably be best to trace wiring to/from the unit itself.

Thanks, the previous DME had exactly the same issue, and I double/triple checked wiring. The mechanic working on this car before recommended I check the Junction box, as apparently there has been an issue to them on the previous model ? I had no clue. Anyway, I spent 3 hours today removing the glove box, the Junction box and JBE, and checked all connectors... everything is perfectly clean, not a spot or sign of overheating or electrical spark.
Never talking to that guy again, he also recommended DME swap, which was a waste of time and money

[langsbr]

Originally Posted by torrque

what is STFT? Thanks.

short term fuel trims. If its adding excessive fuel or removing to much, that could be leading to your problem. Interesting on the battery voltage as well. As FCobra94 said, it's definitely an electrical issue, but trying to figure out exactly what is the fun part.

[torrque]

OK, I am unable to monitor short term fuel trims, but I cam monitor PWM for the LPFP with Carly.
What I noticed, there is a direct correlation between stumbles, and value of PWM i.e. high volume request sent by EKPS module to the pump; that is also when voltage on the car drops by 3 V almost at times. Faulty EKPS ??

14.421874 3.251953 48.295593
12.289062 2.353516 99.000549
11.984374 1.586914 63.693237
12.695312 3.110352 50.334167
13.203124 2.241211 58.259583


I opened up the rear seat cushion side, and it does not feel hot or anything, looks clean, connectors are fine, re-plugged them in. Connection to pump under the seat is also fine.... no wires stripped or anything out of the ordinary. Could EKPS trigger a power event that strong to take down the DME ???

I read that these need re-programming on the car if swapped, so I decided to make a booking to my favorite BMW indy, see if they have one, or what they say.

Thanks all!

[Joe@TopGearSolutions]

I have heard of people buying injectors on eBay under the presumption they are rebuilt (which can't be done). May need a new set from a reputable source, such as FCP Euro.

[musa]

Have you checked the DME cooling fan ? When my car had the same symptoms as yours, had to replace the DME and its cooling fan (the fan would turn off intermittently). Problem went away immediately and has never happened again. I still get PTSD from that experience of the car going into Limp mode when it's warmed up and under acceleration, especially on the freeway. Like you, I replaced so many parts including throttle body, both fuel pumps, fuel sensors, pressure sensors, rebuilt turbo, walnut blasting, solenoids, turbo solenoids, etc. It was a nightmare. But the good thing is that after the fix, my car is now like new .... and I also did a complete suspension overhaul. So it all ended up good.

Note: The DME and cooling fan were replaced at the dealership- Crevier BMW Santa Anna. Got a great deal on parts and labor. Came to around $1,800 out the door including labor and programming. I bought the parts from their online outlet.

Don't give up and good luck!

[torrque]

Originally Posted by Joe@TopGearSolutions

I have heard of people buying injectors on eBay under the presumption they are rebuilt (which can't be done). May need a new set from a reputable source, such as FCP Euro.

But mine are legit parts, purchased from rockauto.com, not ebay... index 12. I called the shop and they said owner supplied the injectors; called owner, he was good enough to send me the receipt from rockauto.com.

[torrque]

Originally Posted by musa

Have you checked the DME cooling fan ? When my car had the same symptoms as yours, had to replace the DME and its cooling fan (the fan would turn off intermittently). Problem went away immediately and has never happened again. I still get PTSD from that experience of the car going into Limp mode when it's warmed up and under acceleration, especially on the freeway. Like you, I replaced so many parts including throttle body, both fuel pumps, fuel sensors, pressure sensors, rebuilt turbo, walnut blasting, etc. It was a nightmare.

Note: The DME and cooling fan were replaced at the dealership- Crevier BMW Santa Anna. Got a great deal on parts and labor. Came to around $1,800 out the door including labor and programming. I bought the parts from their online outlet.

Good luck!

Thanks for this, I will need to check; it is actually very cold now in MA, close to freezing, I doubt the DME is heating up that quickly, but I'll surely check it out. My hickups start as soon as 30 seconds after I start the car....

[torrque]

So the cold has come down on me, and I am running out of time and out of cars... My baby (Shelby) is parked for winter now, and I need the occasional run to shopping and gym, need a car.
Took her to German Performance in Brighton, it's a shop I used before, I trust those guys.. Will report back; hopefully they will find the problem.

[torrque]

Problem fixed; it was the DME relay which is in the ebox apparently. It was cutting the power in and out for the DME, and causing the bucking. I also had a faulty crank angle sensor (which is weird, as it was replaced not long ago, but anyway), she purrs like a kitten now

Thanks all for suggestions

[torrque]

Darn. It is back, problem has returned. It is still bucking, but only so often, much less often than before.... Being that they replaced the crank angle sensor, and my rpm's drop to zero when it happens, I will do some digging to the wiring to that thing.

[torrque]

Car is back from the German Performance shop; they have no clue how to fix it ! They gave up after 2 weeks of investigation. I paid 500 bucks for nothing...

Now, one thing DID happen. They changed the crank angle sensor, and gave it back to me saying problem fixed. But they did not drive it enough. As soon as it warms up, it start shaking again; but only when warmed up properly.
So back it went with them, and it spent another 2 weeks there.... They also swapped th complete wiring to the DME from the crank sensor, no change. They ran another factory ground cable to make sure there is no ground problem, no change.

I am at a loss; at this stage I bought an oscilloscope and will try to scope some of the signals from the crank angle when problem happens. Not sure what else to try, major problem is that DME is error free... no sign of the issue.

I also ran with a fully charged battery with alternator disconnected, same problem. Shake returned as soon as engine warmed up....
If you have any advice (apart from splitting it and selling for parts ) would be appreciated.

I will try to pull some logs with MHD (bought stage 1 maps, I was so glad when they said they fixed it , but dropped back to stock when I noticed problem is still there ) and post , see if we can see anything obvious.
The only obvious thing I see from my logging is a small voltage drop when problem occurs, from 14.x to 11.x V ; all the time.

Many thanks

[torrque]

So just to recap, car has:
New fuel pumps (both)
New Injectors index 12
new Waterpump and thermostat
walnut blasting done in summer of 17 (driven less than 1000 miles since)
New OEM battery
New alternator
New high fuel pressure sensor
New spark plugs and coil packs
New crank angle sensor (and wiring to it just replaced)

No misfire codes what so ever; starts and runs fine, until it warms up starts bucking from time to time, stuttering and RPM needle drops to zero, and recovers withing a split second.

[FEDE/E92]

Have you checked your tmap?