[fyllt]

Hi, I have a weird cold start and we can't figure it out. A couple dealers didn't find anything too...

I've noticed in summer on cold start revs were jumping up and down(this never happened, just when the MAF sensor was not working). I changed the MAF sensor and it didn't help, so I just drove it and ignored the rev jumping at cold start.

After a couple of months, I noticed the car started swinging on a cold start, it felt like someone was standing at the side of the car and moving the car from side to side, also revs were jumping up and down. I was looking at live parameters and noticed that always this swinging went away at 50C temps and EGR went from 20% open to 0%, airflow went from 500 to 300.

After another month, I noticed the extra vibration on a hot engine. When I checked I noticed that the airflow should be 300, but it was showing 500, and EGR was always closed (0%), when it would open the airflow was reading 300 and the vibrations stopped until EGR closed again and the airflow went back to 500 and the car was vibrating badly again.

We tried disconnecting MAF, disconnecting EGR, cleaning EGR, which didn't help, and then we just mapped out and sealed EGR, which didn't help too. We thought that it was EGR problem 100% because of how it randomly was closing and opening and how car felt different each time EGR opened.

Now here is an interesting thing, it was happening before EGR and DPF delete and it's still there - on cold start when I turn on climate control with min temps (16C) it's still swinging from side to side, and when I put climate control to max (28C) the swinging stops right away, this helps till engine gets hot, once it's hot it still vibrates heavily, because airflow is 500 and not 300 as it should be.

It's not glow plugs nor glow plug module, I had bad glow plugs and I know how they feel, they feel like a small misfire, but this feels like the car would be a ship in the ocean with heavy waves hitting it from one side to another. There is no error code in DDE, it happens only when temps are below 50C(swinging) and vibration when hot engine. Cold or hot car pulls very very good.

Yes, I have new glow plugs and module, yes a new MAF sensor installed, yes EGR was mapped out by real professionals not random Bob from a random garage, according to the software injectors are perfect. We can't figure it out, I feel that it's something related to fuel or air, but I'm not sure where to look more. Car throws 0 smoke on a cold start (-10C) and it starts instantly at these winter temps. Any ideas?

[PhaceN52]

Have you ruled out the transmission? I know it may sounds dumb but torque converters locking up can cause all sort of huge vibrations, but still doesn't explain all you said about the EGR opening/closing affecting the vibration.
Look at the video in this topic
https://www.reddit.com/r/Justrolledi...t_it_in_drive/
I'm looking at the N47 on realoem but really can't figure out why it could do that, do you have other informations about this problem?

EDIT: or maybe the jumping parameters you are seeing are the result of the DME trying to regulate the engine based on that load from the torque converter that shouldn't be there

[fyllt]

Hi Phace,

Yeah, the EGR closing, and opening was affecting airflow, which affected vibrations. The vibration is coming from an extra 200 airflow that the engine doesn't need, but I can't figure out why it stays at 500.

When it comes to the torque converter, the transmission was fully serviced 2 years ago, changing gears perfectly, grabbing instantly when releasing the brake pedal, and adaptation values are pretty good almost all in a perfect range... And it doesn't explain why that swinging is only till 50C, after that, it stops swinging and just vibrates, because it doesn't change to 300 airflow from 500(500 is normal for 320d cold engine, later should change to 300, but then another question why it's swinging at cold start?).

When changing the climate control temperature from 16 to 28C all I can see is changing air flow and fuel pressure, so it has to be something with it.

P.S. If I put in Drive, SportDrive, or Reverse it drives away like nothing was happening(just an extra vibration). You can really feel only in park and on a cold engine.

I just watched your video and it's nothing like that it's more like 3 cylinders working, but very, very smooth swinging. Kinda hard to explain, in all my years I never felt something like this.

I had read about vacuum leaks, dirty idle control valve, bad sensor for fuel pressure, etc. etc. etc. but all of them are talking about rough idle and RPM needle jumping on cold start, but this is something unique, the engine feels like someone was standing near drivers door and swinging car from side to side.

I agree with you that it can be something else, and DDE/DME trying to compensate with extra air, but according to my logs, engine torque is in the same spot as before all this started happening, so I guess it means that engine ain't trying to give itself extra power for something? (could be wrong?)

Edit: One time, engine was vibrating and I was super pissed so was pressing the pedal to the metal and after a few hard runs, I felt the engine working fine again, looked at airflow it was showing 300. I went back home, turned the car off and it was fine for a week, later started doing its thing again, so we were 100% it was dirty or faulty EGR sending bad data to the computer, and in return engine wasn't working as it should be, but after EGR delete, problem is still here and that means it wasn't EGR, but why it started working normal again after hard runs? I tried to do the same thing again but could not replicate it.

[Tambohamilton]

Is your AC on or off?

[PhaceN52]

Was the egr badly dirty? Was writing something about the DPF but saw you deleted that, very strange, it's really like a mechanical riddle, I want to know too
Ruled out injectors? So maybe the fact that the swinging goes away at 50°C has something to do with the cold start logic of the engine, as putting the climate to 28°C maybe forces some kind of faster heat up, maybe acting on ignition in addition to the thermostat, as you said something fuel related... any km/l increase?

[fyllt]

Tambohamilton

AC off.

Phace,

EGR was clean as new, in the past I changed 3 EGRs, and all were clean, but the electric part just always failed and the EGRs were brand new, not used. That's why we thought it would be the EGR electric part again because of random closing/opening and that's why we went with deleting EGR from the car, but EGR plays an important role to DPF, so we had to delete DPF too.

According to the bimmer-tools software injectors are perfect, but I guess we will have to take them out and rule this one out too...

Km/l is the same as it was, but because it was a reputable company that did the EGR+DPF job, they offered me stage 1 for 50% off, so I went with it and the same day I installed xHP stage 2. So it should be a bit lower km/l reading but they are exactly the same.

BOOM! New symptoms that I spotted today, didn't have these 3 days ago when I last drove.
1. When driving and pressing the brake pedal it doesn't feel like a normal braking, but more like engine braking first, feels like the engine wants to stall, but quickly corrects itself.
2. When driving and pressing the gas pedal power is slowly increasing, even tho I'm not pressing more, I'm holding it steady. Once I lift my foot a little, it still produces the same power, even tho I'm pressing 10% less accelerator.(feels like some delay or something).
3. If I'm going at the same speed at the same RPMs, and holding the gas pedal at the same position for a long time car starts to jerk, it feels like it doesn't know what to do: to speed up or to slow down?
4. When driving economically, before any gear change it feels like someone is pulling me backward from behind, again like the engine wants to stall between gear changes or it feels more like if I'm lifting my foot from the accelerator between gear changes.
5. Now here is the funny part, if I lift my foot from the accelerator between gear changes, the RPMs jump about 200 more before changing gears... Can these symptoms be related to injectors? Maybe a fuel pump? Or just a bad sensor that is giving bad data to the engine? Again 0 error codes in all modules.

Now that there are new symptoms I'm hoping that it will give a better clue to the mechanics of what could it be. Got to love this car, spent 10k fixing it and still can't drive it properly... ;/

[Tambohamilton]

Fuel filter?

[PhaceN52]

Originally Posted by fyllt

Tambohamilton

AC off.

Phace,

EGR was clean as new, in the past I changed 3 EGRs, and all were clean, but the electric part just always failed and the EGRs were brand new, not used. That's why we thought it would be the EGR electric part again because of random closing/opening and that's why we went with deleting EGR from the car, but EGR plays an important role to DPF, so we had to delete DPF too.

According to the bimmer-tools software injectors are perfect, but I guess we will have to take them out and rule this one out too...

Km/l is the same as it was, but because it was a reputable company that did the EGR+DPF job, they offered me stage 1 for 50% off, so I went with it and the same day I installed xHP stage 2. So it should be a bit lower km/l reading but they are exactly the same.

BOOM! New symptoms that I spotted today, didn't have these 3 days ago when I last drove.
1. When driving and pressing the brake pedal it doesn't feel like a normal braking, but more like engine braking first, feels like the engine wants to stall, but quickly corrects itself.
2. When driving and pressing the gas pedal power is slowly increasing, even tho I'm not pressing more, I'm holding it steady. Once I lift my foot a little, it still produces the same power, even tho I'm pressing 10% less accelerator.(feels like some delay or something).
3. If I'm going at the same speed at the same RPMs, and holding the gas pedal at the same position for a long time car starts to jerk, it feels like it doesn't know what to do: to speed up or to slow down?
4. When driving economically, before any gear change it feels like someone is pulling me backward from behind, again like the engine wants to stall between gear changes or it feels more like if I'm lifting my foot from the accelerator between gear changes.
5. Now here is the funny part, if I lift my foot from the accelerator between gear changes, the RPMs jump about 200 more before changing gears... Can these symptoms be related to injectors? Maybe a fuel pump? Or just a bad sensor that is giving bad data to the engine? Again 0 error codes in all modules.

Now that there are new symptoms I'm hoping that it will give a better clue to the mechanics of what could it be. Got to love this car, spent 10k fixing it and still can't drive it properly... ;/

Well done with the tune after egr+dpf delete, at that point...
The new symptoms you're describing feel even more something air related, on the gas engines (at least early n52s) there's a problem with maf sensors not being able to read correctly airflow caused by a combination of oxidation on the pins of the connector and the line between em and the dme being low voltage, so even a small discrepancy causes a bad reading leading more or less to the last symptoms you're describing. If you have a "dry" contact cleaner spray that leaves no residue maybe you can try to pull and clean the throttle body connector and pins, charge pipe sensor socket and connector of the electric motor on the intake manifold (realoem numbers 3 and 4, is called receptacle housing there, don't know what is that)
and basically everything electrical related to air, to see if it changes something.
Then if I recall correctly an e90post member who rebuilds n54s said time ago that the almost-stalling could be also caused from a leak in the brake booster, probably has something to do with the engine vacuum, do you have the classic hard brake pedal after letting the car sit overnight?
If you have a floor jack just for peace of mind you can also maybe rule out badly sticking brakes (for the almost stalling), but that would not explain the rpm jumping

[Tambohamilton]

Are you sure you're using decent fuel, and no additives?

[fyllt]

Phace

"Well done with the tune after egr+dpf delete, at that point..." SARCASM? ;D

Hmmm... When I first started to see RPMs jumping on a cold engine, I thought about a bad Mass Air Flow sensor, but I had a bad one before and it didn't swing the car like it does now. So this is something weird and can't figure it out. Also, I changed the MAF sensor 5 months ago with a brand new Bosch firm, deleted old MAF memory and all was good. I took it out 1 month ago, but it was looking as new, so didn't do anything to it(still better to clean it?).

The intake manifold engine is irrelevant to me, I washed the intake manifold 2 years ago and I deleted the swirl flaps too because they like to drop inside the engine, everyone was saying it's better and safer to just delete them.

Hmmm... Interesting about the pins and voltage, unfortunately, I can't do that because I already left the car at BMW service. I don't know, I also feel like it's air-related, but not sure, I hope the BMW service will have something to tell me because it drives me nuts. Most of the time I find the problem myself, I just don't have the place nor tools to do some jobs, so I go to car service by saying "I need to change this or do that", and now I'm going with "car does this and that and I have no clue what's going on".

EDIT: By the way I saw YouTube videos that an easy test for MAF is to disconnect it while the engine is running and the engine should stall, if it won't then you have a bad MAF, is it true to BMW too? Logically if you're driving and MAF stops working and the engine stalls, then it could lead to unnecessary accidents/deaths.

The brake pedal is normal after night unless I press on it a couple of times when the engine is off.

Tambohamilton

I use pro diesel fuel from Neste gas station. Been using it for the past 2 years. https://www.neste.com/neste-pro-dies...-best-diesel-0 1.7eur/l or 6.46eur per gallon, or 7dollars per gallon. I never used any additives.

[Tambohamilton]

I'll be interested to hear what they find

P.S. that's some cheap diesel!

[PhaceN52]

Originally Posted by fyllt

Phace

"Well done with the tune after egr+dpf delete, at that point..." SARCASM? ;D

Hmmm... When I first started to see RPMs jumping on a cold engine, I thought about a bad Mass Air Flow sensor, but I had a bad one before and it didn't swing the car like it does now. So this is something weird and can't figure it out. Also, I changed the MAF sensor 5 months ago with a brand new Bosch firm, deleted old MAF memory and all was good. I took it out 1 month ago, but it was looking as new, so didn't do anything to it(still better to clean it?).

The intake manifold engine is irrelevant to me, I washed the intake manifold 2 years ago and I deleted the swirl flaps too because they like to drop inside the engine, everyone was saying it's better and safer to just delete them.

Hmmm... Interesting about the pins and voltage, unfortunately, I can't do that because I already left the car at BMW service. I don't know, I also feel like it's air-related, but not sure, I hope the BMW service will have something to tell me because it drives me nuts. Most of the time I find the problem myself, I just don't have the place nor tools to do some jobs, so I go to car service by saying "I need to change this or do that", and now I'm going with "car does this and that and I have no clue what's going on".

EDIT: By the way I saw YouTube videos that an easy test for MAF is to disconnect it while the engine is running and the engine should stall, if it won't then you have a bad MAF, is it true to BMW too? Logically if you're driving and MAF stops working and the engine stalls, then it could lead to unnecessary accidents/deaths.

The brake pedal is normal after night unless I press on it a couple of times when the engine is off.

Tambohamilton

I use pro diesel fuel from Neste gas station. Been using it for the past 2 years. https://www.neste.com/neste-pro-dies...-best-diesel-0 1.7eur/l or 6.46eur per gallon, or 7dollars per gallon. I never used any additives.

No man I'm serious, did well of taking advantage from that removal, said that 'cause I'd like to go catless too but it's basically impossible here (when the real criminals are inside the parlament but let's forget about it...)

I don't know what would happen disconnecting it while it's running, as you said logic would have it running the same... If you start the engine with the sensor unconnected it should run on fixed maps
Good for the new maf the swirl flaps and the brake booster, at this point let's see what they'll find out and eventually let's move from there...

Tamb, those are normal prices here in EU sadly
took a look at gasprices.aaa, 2.8$ gal, 3.153$ national average, my eyes are bleeding

[fyllt]

Originally Posted by Tambohamilton

I'll be interested to hear what they find

P.S. that's some cheap diesel!

All I can say about EU gas prices is this lol. -

Originally Posted by Tambohamilton

Fuel filter?

Just saw this now - I change the oil and all filters - oil, air, fuel every 8-10k km or every year, depending on what comes first.

Phace

I see, I see. ;D

I found this video and it explains why this MAF test is crap -

Yeah, now we wait... ;/

[Tambohamilton]

Even worse in the UK...

[fyllt]

Originally Posted by Tambohamilton

Even worse in the UK...

Damn just checked UK premium diesel price, 2.1eur per l? We had these prices 2 years ago but went down a bit...

[Tambohamilton]

Yeah, something like that. £1.55/L for standard stuff, at the cheaper end of the scale.

I use standard diesel and add millers diesel ecomax (mainly 2ehn), which seems to work nicely. I tried a different additive recently, and thought the turbo or DPD or something was failing!

[fyllt]

So,

After 2 weeks and a lot of troubleshooting, checking live data, and testing here's an update:

1. The weird jerking that I wrote - "If I'm going at the same speed at the same RPMs, and holding the gas pedal at the same position for a long time, the car starts to jerk, it feels like it doesn't know what to do: to speed up or to slow down?"

Was related to transfer case fluid, changed, and all is good now. At the same time, we changed the engine oil, oil filter, air filter, fuel filter, and climate control filters.

2. The weird, swinging/shaking, knocking, RPMs jumping, changing gear RPMs jumping, too much fuel eating, too much air sucking, EGR fully opening/closing 45 times per minute, and too much vibration was related to injectors!!!!!!.

First, we watched live data and found out that 1 injector was pissing into a cylinder, the second time we checked(after a week), we found out that 2 injectors are faulty, so we took out all 4 and sent them to a company that test them. We found out that 1 injector was always pissing, 2 injectors couldn't hold pressure, so they didn't spray enough fuel and only 1 injector was perfect! lol.

Now the car eats 2x less fuel, on cold start there's no swinging, doesn't care if climate control is on or off, no more knocking, no more RPM jumping on a cold engine start, no more extra air pulling, no more RPMs jumping when changing gears and no more feeling as engine braking when releasing gas pedal. Now the engine works perfectly! )).

[Tambohamilton]

Awesome, well done!