Stumble from stop light under mid to heavy throttle
 

2001 X5 3.0 from a start, stumbles like it is not getting power, from stop only. More so when fully warmed up.
Changed intake cam sensor. Exhaust was done about 30k ago.
DISA checked and fine. Idle control valve was cleaned about 20k ago.

Could be:

• Throttle position sensor,
• crankshaft sensor,
• trans solenoid,
• wheel speed sensor, or
• air leak
• transfer case gear?

No codes. 260k miles
I do need to replace my drivers side Fuel Tank Sending Unit as after a fill up the fuel level did not come back. It came back after a week full of gas though.

How old is the fuel pump? Feels like fuel pump

How old are the plugs? Has the VANOS ever been rebuilt?

vanos rebuilt about 60k ago - full rebuild

Fuel pump replaced about 30k miles ago

perhaps the one side of tank is not sending fuel since the fuel level sensor seems bad

The float for level doesn't interfere with fuel delivery, however if you don't know how much fuel, add enough to know you have 1/2 tank and test.

Siphon jet problems occur close to 1/3 to 1/4 tank and could cause a delivery problem but usually it isn't power problems it's fuel starvation stall.

When fuel pump is near end of life, the FPR will hide a weak pump and symptoms show up under moderate to heavy demand.

i have 1/3 tank, only and issue from stop and med to hard acceleration for about 2 seconds until it gets going. RPM / Torque related I am thinking.
throttle position sensor
exhaust cam sensor
crankshaft sensor
oxygen sensors
smoke test?
Fuel Tank Sending Unit
Fuel pump
wheel speed sensor
clean maf

Tested in neutral, misses when tapping throttle, goes away on after a second . No cel. Original coils. Bad spark plug? Only 23k on plugs. MAF or TPS is my guess. I have Autel MaxiDiag MD808 Pro perhaps I can run live data

Stumble from stop light under mid to heavy throttle
 

Track real time TPS values can your scanner graph? Also pedal sensors.

Then: fuel pressure while hitting throttle. It should be dead flat no waver.

I'd take another look at the ICV, even though you cleaned it 20k miles ago. Easy to check and to clean. I think it would provide the symptoms you're seeing. And it could be that your cleaning did not get all the gunk.

i should clarify, it is bogging down when tapping the throttle for about a sec. Seems to be something at initial throttle / fuel to air ratio? will do some tests and see
Tested cold start up, replaced the air filter and does not bog down. Will test with it warm and then run those tests, thanks!

Find live data for the pedal sensor and TPS. If you can, graph :

Both pedal sensors
Both TPS

High TPS & high PS
Low TPS & low PS

If there is a dead spot on one of the sensors it will show up there.

I would measure fuel pressure

I replaced the air filter, so far so good, will give it additional driving. 16k on air filter in Arizona, dirty but seen worse.

was 1/2 quart low on transmission fluid, so far so good. Added while running and will continue to test.

keep getting p1247 - cyl 3 misfire. swapped coils with 1 and 3. no oil in plug. Pulled plug and looks fine. test drive provided no issues. continuing testing.

top up while running and cold

Transmission spec to fill at a precise temperature like 30-50c.

is there a lifespan of coils? Mine are original, 260k Bremi 2001

Stumble from stop light under mid to heavy throttle
 

Ohh…. Swap those Bremi’s out with the Bosch. The Bremi’s were known to have issues. Mine started acting up around 74,000 miles.

I’ve also been told, to check the Bosch mfg. dates. There were some issues there as well.

MAF, DISA, Vac lines, and O2’s also help cure that stumble. It will never totally go away though, I think it is a characteristic of the M54.

That's not true Happy. The M54 is a silky smooth engine. But getting it there... well yeah, you hit the headliners. DISA, MAF, vac lines (and gaskets, intake, boots, VC, etc), o2 sensors, VANOS, coils and plugs. I haven't seen many fueling issues with the m54 so I skip injectors and FPR unless something indicates an issue there.

I don't mess around with the above. When I buy an M54 with > 120,000 miles all of those things get done. Only way to own a smooth M54 at the age they are currently. I just did the same with our N52... people have the same complaints about those engines.

Sometimes you just have to bite the bullet.

EDIT: BTW, I am excluding yours as it is a special case scenario, not many like your M54 running around out there. ;) You might have to live with a slightly less than smooth M54. But it makes up for it with smiles and power I'm sure.

With the manual, there is a dead spot from a dead stop even with every repair mentioned. It’s less pronounced when everything is running 100%. The supercharger kind of had an affect on it, but only slightly. It’s definitely not as noticeable though when the M54 has had a total refresh. I can use the clutch to completely avoid it. But, as well I can hit that dead spot like clockwork if I want.

Never had dead spot on either of our M54. I have one on N55 for the first minute on a cold start.

I wonder if the E53 has a clutch delay valve like the E39 manuals did?

Yep, E53 does come with CDV. It was terrible when mine was due for maintenance. Cam, knock, MAF, DISA, coils, vacuum leaks, etc. combined with the CDV was a pretty lack luster experience, especially with only 230 hp. When looking at the live data while operating, nothing shows when the hesitation or dead spot as I like to call it takes place.

The fashion in which my E53 sits currently, the dead spot is nonexistent. I’d have to go hunting for it to find it. It requires letting the clutch out at maybe those most 1100 rpm, having drop down to say 950 rpm, and then once the clutch grabs fully, lay into the pedal a bit, and usually it will hiccup. LoL..

Before the massive tune up though, it would hiccup letting the clutch go at 1300-1500 rpm. I had to learn how to get into the throttle in a manner that wouldn’t cause the hesitation.

Word of advice to at least M54 owners, stay on the maintenance, and the hesitation should cease.

There is a lifespan, but it can be pretty long. My 2001 3.0i at 203k miles is still on its original Bremi coils, with no problems there. I'm not planning to replace pre-emptively, but will not be surprised if they start to fail any time now.

My M54 with the AT is really smooth running and especially when starting out from a stop.

Wow your Bremi’s held up for the long run! Mine were toast. I definitely had the defective part #’s. Plus when tested, failed the threshold.

No need to replace if there are no misfires.

One thing I forgot to ask the OP. At what rpm is the hesitation happening?

about 30 miles driven, coils appear to be the issue. took all apart and cleaned with electrical contact cleaner. No more issues and running smoother. Probably a good idea to clean all coils every 100k miles before replacing.

Thanks for the update OP. Hope it's sorted for you now. :thumbup:

On the other hand though, however this anomaly happens in my case from a dead stop. If you commit to a full throttle and time it right, combined with the super short 1st gear that the manuals have, and at least on my build. You’d better hold on to the wheel tight, and not bounce it off the rev limiter excessively.

So it’s not like it’s misfiring or running poorly, which the live data proved. It actually makes for a great launch, without aggressively dumping the clutch.

In any event, I don’t drive my X that aggressive anyway.

I am glad you found the problem. My Bremi’s were shot early on.

Did you disconnect/reconnect grounds? It's a not too uncommon issue for coils to malfunction when a ground is loose and if memory serves, multiple coils share a ground so a bad ground can affect multiple coils so hopefully reworking those connections will be resolution.

Scuffing the grounds helps as well. The cleaner, the better. But as Andrew said, keep the grounds tight! A loose ground can even possibly cause damage.

UPDATE
Turns out it was my front drive shaft splines wearing out causing bogging down/slipping. Solution is 1 inch longer front drive shaft splines.
New drive shaft on ebay or https://www.tcbmwx5.com/ around 400 or you can take your old one and cut it and get a welder to put a 2 inch extension but needs to be balanced and I just bought the whole new one.
Also bought
New Giubo
New Giubo bolts and nuts
E12 torx socket
3/8 extended flex head wratcht
grease for new rod
Instructions https://www.youtube.com/watch?v=id5T...TCBMWX5.COMCEO
Tips https://www.youtube.com/watch?v=fEpt...channel=50sKid

I have 260k and 17 inch rims so your mileage may vary.
Figure out your parts from https://www.realoem.com/bmw/enUS/select

Looking at all the posts, and seeing what you found was the problem, the Aww hell no, Really! comes to mind. Iwas just going to suggest check your fuel filter aas it was not mentioned and it was pexectly what caused the same problem with mine.
Glad you are up and running again, there is certainly a mountain of knowledge and experiences in here, that is for sure.

I ended up giving up trying to get front shaft into my old transfer case, I bought a new shaft and rebuilt transfer case from https://www.tcbmwx5.com/
check your splines, if they look like mine below, you need a transfer case. 4 hours of filing did not work due to the first inch of splines were half broken off and the torque kinda bent them, no way to get it in. 4 days of trying and figured with 260k prob worth it to get a rebuilt. Plan on keeping car for another 5 years so will see.

after filing for 4+ hours with small flat and square files.

https://i.postimg.cc/6QjS9d23/PXL-20...-052046269.jpg

It looks like the original shaft never was in there that far... I get hand cramps thinking about filing that much at my age :rolleyes:, the end of the transfer case looks like it was hammered a bit as well or is that an optical illusion?

bmw updated the design in 2004, but 2000-2003 had a 1 inch spline, updated kit is 2 inch which fits and how it should have been. V8s strip them at way less miles.

If you had the longer shaft and couldn't get past the damaged splines, the solution would be to cut off the damaged part. I would use a rotary tool with emery stone. Or replace the output "shaft" if you can get that part by itself.

Also; I made a tool for cleaning up hub spline from an old CV axle. Possibly the same can be made from the end of your old prop shaft (cut off the damaged end and have some nice squared off teeth to use as machine cutting tool).

Symptoms: seems like the engine is missing occasionally on cold start, when in gear, seems to loose power in high torque starting situations like a hard turn from a stop or taking off from stop.

New development. When I filled up the tank, the issue seemed to go away.
Could be
Less ethanol in my latest fill up?
or
Fuel pressure issue caused by fuel pump, which is 35k old.
or
I have had an issue with the fuel level sensor - it stopped working after a refill a few months ago, worked a few days later, I supposed it was near empty for too long and got stuck / old.

Could be totally not related though

Recent repairs.
I replaced transfer case and shaft, new Giubos front and back, new bolts and nuts, new Transfer case fluid.

Next step
Bought a new fuel level sending unit (drivers side) and perhaps the existing one connection is bad or worn after 261k or the sending unit is not picking up or partially clogged when low fuel?


Bought new coils and plugs to be installed

Could be bad Transfer case but it was rebuilt from a reputable place and the 1 inch longer shaft would not slip when both shaft and TC are new.

From YouTube Nathan's Garage, bad coil packs may not give engine codes. It's a good place to start.

Update
Turns out one of the coils had a gap due to a rubber spark plug socket breaking off down in the spark plug hole and keeping the coil from seating. I will never use those rubber sockets again, will use magnetic.
I replaced all coils and plugs with Ruthenium HX NGK plugs. Runs flawlessly. So for 24k miles the car intermittently missed on cylinder 3. I had swapped coils as I got a code, and have gotten random P codes for misfire, FINALLY FIXED!

Nice find. I went to magnetic 16mm sockets for overhead cam engines. Two extension lengths. Plus one deep socket. A combo set is cheap on Amazon. You'll like the HX NGK plugs. I installed some with new coil packs.