Throttle tip-in issue/stumble (3.0 5-speed)
 

I have a throttle tip-in stumble that seems fairly common for the M54 engine but in doing research haven't found any smoking guns. Before I open up the parts cannon I wanted a bit of help troubleshooting. Just over 160k miles on the vehicle and pretty much all original except for the stuff I've done.


Just off idle, when trying to accelerate, the engine feels like it bogs down for a split second before it catches. Once it catches, the engine feels healthy.


I've been poking around OBDFusion and INPA for anything obvious. The sample rate is slow for either so its hard to see transients like this, but nothing obviously off with the mass air flow, air intake temp. I also did a smoke check on the intake to check for vacuum leaks and did not find any. Long term fuel trims on both banks is +1.6%. No stored codes.


I've already replaced the plugs and the VANOS seals as I read these can cause similar symptoms, no obvious difference from either. I have not yet replaced the coils, MAF, or O2 sensors.

One thing that seems odd in INPA - checking the PWG/MDK values (the pedal position sensor vs throttle position sensor), intuitively these should roughly be in sync with each other unless I am understanding this system incorrectly. I assume there are redundant sensors for both to measure the driver's desired throttle input and and actual throttle position. the PWG sensors react immediately but the MDK ones barely change. Also, the sensors for each set aren't in sync with each other (i.e the two PWG sensors have an offset, and the MDK sensors appear to be inverted, one reads 0.5 volt and the other reads 4.5 volt). I posted two images, one at no pedal input and the other with some nominal level of throttle input. Does this mean there's something up with my throttle body?


Any help here is appreciated. Oh, also this is one of those rare 5-speeds. Other than the tip in issue it's great fun to drive!

I thought both the pedal position and the throttle position used inverted secondary pots. I haven't polled mine in a while and can't remember for sure.

If i get a chance i can look but newer chassis so there is a chance they changed since then.

Have a search among the E46 crowd…If anybody has figured it out, it’s the e46 crowd…


No disrespect to this forum…

https://www.e46fanatics.com/threads/...ix-mod.946536/

From trolling the E46 forum, that's what I thought too. What I'm seeing doesn't make a lot of sense.

Yeah I've been reading on the E46 forum and bimmerforums. So far I saw one guy who said a new MAF fixed it, and another who said he had excess carbon buildup from running hot.

MAF is a good guess but you won't know until you replace it. Carbon could be a problem especially if you aren't using premium fuel.

I haven't used either, but what about Sprint Booster OR mapping the throttle yourself with MS4x.net ?

They look more promising than the MAF or carbon buildup.

https://www.e46fanatics.com/threads/...oster.1315523/

I've only had the car for about six months so not sure what fuel the previous owner used. I have Bg44K in the tank just in case.

My E36 had the carbon build up problem, about as bad as you could imagine. 25 years of New Jersey 87.

It was consistently the same throughout the entire rev range, nothing unusual off the line. It was just bogged down and tired through the entire rev range. You give it full throttle and it didn't want to do it.

I ran a few cans of berryman b12 through the fuel and the crankcase, that helped a little bit. I used the liqui Moly engine flush twice, that helped a little more. A lot of people say not to use that as it can dislodge something etc but I've used it a bunch in all my cars and been lucky. It does help. But I still had to take the head off and clean it by hand. It's normally responsive now, but I did about 60 other things in addition to the carbon cleaning.

I don't think carbon is your problem.

My f30 does all this kind of crap, it's the computer. The dsc, and the e differential, torque , limiter, dual mass flywheel protection nonsense. Some of this can be coded out but it's an uphill battle on that car. Sometimes off the line I'll get exactly what you describe, and then into second it cuts out. Then there's shadow codes for flywheel protection.

I am thinking about this. It does feel like it could be software or a protection thing like you describe. Maybe there's a software limited throttle or power application depending on clutch position? I did notice the clutch switch shows "disengaged" in INPA until the very top of travel. One of the things on my list is to check that switch wherever it lives. I know on the old Hondas I used to have that switch was adjustable.


Edit: Looking at the replacement clutch switch it doesn't look adjustable. Darn.


To clarify though - your E53 does not have the same problem as I describe, correct? i.e it's not an intended effect of the programming that would have been present in the car when new?

I've done this sort of thing on a motor- and ecu-swapped Fiero in another life, but on a stock X5? If I knew the car came this way then I'd be open to trying it.

I think it does come this way... You've described the standard M54 drive by wire lag.. It's why a lot of people prefer the drive by cable of M52 and earlier

Cable throttle would be nice I think. I don't have any of this stuff on the m52 car. It will just does what you want it to do and has no ability to question or change anything. It did have a cable traction control thingy that was easily deleted.

With e53 once in awhile I'll blip a downshift and it will way over blip near redline. Like no way I did that. The f30 does that sometimes too. The tach sometimes is a little laggy I think the cluster needs a good cleaning. But it's very drivable. No issues controlling the throttle off the line.

It could be the CDV. I deleted that when I did the clutch. I don't think it's really needed on these cars they don't make a ton of power or cause shock. I didn't get maybe more than a dozen drives on the stock clutch but I don't remember having any problems with it. I do bleed the clutch all the time on these cars I find it really helps.

Any other diagnostics I can try for the MAF before I drop $170 on a new one?

CDV just slows the clutch engagement, no?

Sorry for the multiple questions in a row, but can anyone confirm what I am in seeing in INPA regarding throttle position? What I am seeing doesn't make sense unless the computer is playing games, which wouldnt surprise me.

Just based on your description in post #1, I had a similar symptom when my idle air control valve became clogged. Simple fix was to remove it and clean carefully.

That's a very good idea


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You can try rapping on the MAF with your knuckles while the engine is running to see if there is a stumble. (doesn't rule out a bad MAF though) You can also try disconnecting the MAF (key off) and try taking it for a drive. (doesn't mean for sure the problem is the MAF but gives some direction) The throttle pedal pots giving offset or opposing signals is normal. Are you really really sure there are no codes? How old are the spark plugs?

and yep, idle air control might be worth a try.

Thanks all for the suggestions. I will try cleaning the IAC valve, can't hurt.



I just replaced the spark plugs, but did not change the coils. the old ones were the originals. did not notice any difference before and after.

You were right. there was no CEL and I thought there were codes, but sure enough I found a few. I don't think they are relevant here but the translation is pretty tough.


RLS-DS2 looks like the rain sensor which sure enough does not work.
LCM_IV is the light control module?
The IKI EEPROM error is probably because the gage cluster was previously replaced.

I was thinking more DME codes but it wouldn't hurt to clear all. Have you tried clearing DME adaptations ?

I think 80stech has you on the right track. Once cleared see what comes back and I'd do live data to see if something shows up without causing a code if none reappear.

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Checked DME codes and found Code 90, "TEG_UP_1" and Code 91, "TEG_UP_2". Both have error frequency of 0 with message "Error currently not present".


I cleaned my IAC, it had some soot and grime in there, replaced the air intake elbow at the same time. Feels the same though. Still stumbles.

Did you reset adaptations? Can you get code descriptions? even in German, you can maybe use google translate or post the German, I am fairly fluent.

Here are the screen readouts from the DME error codes.


I just reset all of the adaptations but haven't tried it yet.

Doing a quick search on google for you shows that codes 90 and 91 are fuel control and people have found vacuum leaks the cause.

Honestly that would 100% explain it. I did a smoke check and found nothing but that was adding smoke ahead of the throttle body. I'll try smoking it out somehow thru the intake manifold and check for leaks.

Did another smoke check, this time through the "y" joint going to the brake booster. No trace of smoke, unfortunately.


I'm getting close to biting the bullet and trying a new VDO/Continental MAF. From the other forums I see a lot of folks warning not to use any aftermarket brands. A bit spendy but not sure what else to try.

I've never done a smoke test so maybe someone else can chime in on that. A smoke test
might be useful to help find a vacuum leak but doesn't eliminate it as a problem.
It takes a little "finesse" to center the IAC motor back into the intake seal (good to replace that as well) so hopefully you didn't add a vacuum leak there, and hopefully you didn't use carb cleaner on the IAC.

I used QD electronic cleaner. What's special about the IAC and carb cleaner?

Carb cleaner will ruin any rubber o-rings.

I see. The IAC grommet seemed okay, it was still very pliable but maybe I should have replaced it.


I also bit the bullet and replaced the MAF (VDO/Continental), coils (Bosch), and O2 sensors (Denso). It seems somewhat better but it's not completely eliminated (it's also possible it's a placebo effect).


If I had a vacuum leak, wouldn't that show up in the long term fuel trims?


Is it plausible that a slow or lazy IAC would cause tip-in problems?


Does the electronic throttle body get slow or lazy with age?

Others have said that the IAC can make a difference but it really shouldn't and I haven't seen that, maybe they could chime in more on that. I've never heard the throttle body causing that issue but you never know, maybe more likely than the IAC motor ?? What happens when you clear the DME adaptations ??

If you don't know the history it is possible that someone has used carb cleaner to clean the throttle body which could for sure cause it to react slower as the o-rings swell and drag. I would eliminate as much as you can first though.

I tried clearing the DME adaptations but did not notice any difference. I also went ahead and checked my fuel pressure, 54 psi when pump is running, 48 psi when pump shuts down. I understand 54 psi is the specification so this checks out.


Based on my understanding of the idle air system, the IAC allows air into the manifold up until it reaches 100% duty cycle, then the throttle begins to open.
Total speculation but it feels like this handoff is maybe not happening in a smooth manner. Like you said, maybe the throttle is a bit lazy or slow or there's something weird going on with the IAC. Unfortunately these are both expensive parts and I would be buying OE grade parts (the throttle body is $217 at Rockauto).


I wish I knew what this setup was supposed to feel like when new. There are a lot of complaints of similar symptoms for other M54 powered vehicles on the 3-series and 5-series forums.

I don't think the IAC motor works like that but you could check that pretty quick looking at the live data. If it does then IAC motor is definitely on the table. If resetting the adaptations or running with the MAF unplugged doesn't help then it's way less likely to be a vacuum leak.

Before splurging on a new IAC I wanted to take it out again and make sure it's clean, I also saw this thread about lubricating it which I will try. https://www.e46fanatics.com/threads/...n-icv.1043323/


Throttle body looks really clean.


I pulled the spark plugs because one of the other threads mentioned excess carbon buildup causing similar problems. This looks a bit excessive to me but curious to get thoughts. All cylinders look about the same. I'm considering adding some cleaner (such as throttle body cleaner) directly into the cylinders to try and get some of the crap out.

The second pic doesn't look great but I'm not used to looking at broscope pics so hopefully more chime in. The intake valves count too, maybe more. The more carbon that can absorb fuel the worse the problem can be but it's not an exact science. Chrysler had an excellent foam spray (meant to spray in the carb/throttle body with engine running) for carbon back in the day but I don't know if it's still available. I think some of the pro-type (into the injector rail) cleaners work pretty good for carbon too. Your biggest friend is PREMIUM gas.

Just to make sure you are saying more of a tip in slight stumble or hesitation , not bog, right?
Did you verify how the IAC motor works off idle ??

I've seen carbon buildup like that on a few old engines. My advice, drive it "harder"! :bmw:

"Italian Tune-Up", or use Marvel Mystery Oil (or Seafoam)
 

Back in the day, circa late '60's to early 70's, I was entrusted to do the upkeep on my parent's and grandparents cars. Still at home, in college, and having trained at a GM Tech school, I was the person given the job; my grandparents lived two houses down, and had an available garage (our house had one with a utility/washing room + storage roon, with no room for cars), so I at least had a place to work, sometimes.

P.S. I also did my younger brothers' cars, too, and also got the job of getting license plates and tags for everyone, all at once, one day a year (I often had to spend up to eight hours in line). And, I also dropped everyones' tax returns off at the post office drop-point (open 'til midnite). I was the "good son", and so it went.

My parents and grandad (grandmother hadn't driven since 1935) had helium feet (as opposed to my lead foot), so their engines woul get carbon-ed up, a lot. It didn't help that my grandad was a big Champion Sparkplug fan, and bought them in bulk for the family...I switched to better brands...A/C, NGK, Bosch later on), and all the cars had points ignitions, so no hot spark, at that time.

So, the first thing I'd do, is drive a car down to the freeway, do several full-throttle runs during a 10 mile loop, and then see whether it ran better. If not (though the "italian Tune-up" usually helped a lot) then I'd repeat the run, using Marvel Mystery Oil (in both carb and tank, killing mosquitoes with the resultant oil fog). After that, I'd do points & plugs. And change the oil (this maintenance cycle was done every 3k miles). Rinse/repeat.

I liked the use of additives from that early date, and have continued to use them ever since. My personal cars never seemed to get carboned-up (lead-foot, long commutes, drag racing, you know), but I'm sure modern ignition parts, and better gas and oil, all help a lot.

Regarding a possible problem with the IACV, I had created and then fixed a problem with very similar symptoms many years ago on my 2001 3.0i. So in that case, there was no doubt about the cause, effect, and solution. I basically took a car that should run well, cleaned the IACV while I had it out, and that cleaning actually caused a problem by freeing up some gunk, causing the valve to not move freely, giving the very slow driving start. Removing and cleaning the IACV more carefully showed the problem (IACV clearly sticking) and solved it.

Here is a thread (which may be relevant in other ways for you) in which I tell the story with a little more detail, and also is probably more accurate due to being older.

https://xoutpost.com/bmw-sav-forums/...cant-find.html

As far as how smooth and well these cars should drive, I will say that of the dozen or so cars I've owned, this is the absolute smoothest and easiest to drive - pulling away from a stop with smoothness, power, no delay, etc. I bought the car as a first car for all my kids to use, and it was perfect for that - safe, easy to drive, relatively cheap to own/operate/insure.

Thanks all for the excellent info and suggestions. I'm going to try:

• Cleaning and lubricating the IAC w/ throttle body cleaner, making sure it moves freely and clicks when gently shaken from side to side. Lubricated with motor oil.
• Clean the throttle plate with throttle body cleaner (although it looked pretty clean already).
• Contact the dealer about this service bulletin. Found through one of the linked threads:
  • BMW issued a Service Measure bulletin for the Throttle response issue. For details ... look up service measure B12 204 04. The DME software needs to be updated.
• Run BG44k in the fuel for at least another tank (been running one tankful already) to try and loosen the carbon deposits on the piston crowns.
• I debated pouring solvent directly into the cylinders such as carb cleaner or ACDelco top end cleaner but this makes me a bit nervous, so I will table this for now.
• I had some BG EPR on hand so I went ahead and used it (supposed to clean out deposits in the oil system), changed the oil.
• I will try the "Italian tune up" and make an attempt to drive it a bit harder.
• I verified through INPA that with with light throttle application, the IAC position changes. I don't have a helper so I couldn't try doing this on an actual drive, and I couldn't give enough throttle in neutral without over-revving the engine to actually get the throttle to open.

I call it a “Clean Out”.! The wife is always saying, “knock it off”! And I say, “Ah, I’m just cleaning her out”. But I’ll tell you, seems to work. :dunno:


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

Throttle tip-in issue/stumble ([emoji2391].0 [emoji2[emoji2391]9[emoji2391]]-speed)
 

I taught my wife that the BMW needed some occasional "exercise".

Yesterday when proofing out a repair to excise some demons giving her engine some rough running cylinders, took her out on the freeway for some full throttle run.

To my surprise a Vette shoots by me right as i hit about 80.

All lanes clear for about half a mile so "hammer down" caught up with the Vette in a handful of seconds.

HUD indicted 3x36 [emoji1]!

Engine performed flawlessly but then running rough numbers indicate she's overdue some new plugs.

@Masospaghetti--- The dealer should be able to tell you if the programming update has been done, unlikely that it hasn't. If the IAC controls the tip in throttle then I would buy a new IAC motor, good chance someone has used carb cleaner and the o-rings are swollen and dragging a bit.

Called the dealer and that programming actually has not been done but of course it's requires a diagnostic fee of $285 to even start :rolleyes: but probably worth doing to rule it out.


Went for a drive today and the problem persists after the additional IAC cleaning and lubricating.

Is the diagnostic fee taken off programming? Or at least discounted. They will try to find something else to fix.

Well…. You could always take those proceeds and apply them to a Active tune being you have a stick. Pretty sure once the fee is paid, tuning and updating is included thereafter. Double check though. They’ll definitely get that M54 running right! As long as all of your maintenance is up to date.


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

Update - installed a new IAC and grommet (Standard Motor Products brand, pleasantly surprised to see it was made in USA) but no meaningful change in the throttle response. Next step will be to apply the software update.

I forgot to mention this in my previous post (#40) in this thread: I have the same throttle delay that seems common to the M54B30 engine, too.

Having never driven ANY BWW previously, I just assumed that it was normal for the species, and have lived with it as-is. It doesn't bother me much, since I mentally & physically delay throttle application while leaving a stoplight, after being a long-time drag racer, and now refrain from full throttle starts (less wear and tear on the old parts).

I've also found that on my other drive-by-wire vehicles (both GM products: a '04 Chevy 2500HD pickup, and a '09 Chevy HHR Panel), they will sometimes go into limp mode if I tromp on the pedal from idle, so I learned to ease into it, to avoid the problem. The '98 GMC pickup, with a conventional mechanical accelerator installed, has no such a limitation (in fact, the previous owner, a friend I bought it from, previously won many drag races driving it).

Now, following this thread, and with the tip-in delay in mind, I did one lead-footed start yesterday while driving the X5. While it didn't compare well to either the GMC, nor to the memory of my 700+HP '66 Chevelle drag racer, it did leap from the light. I think I'll keep a lighter foot, and my intentional delay when accelerating from idle, and restrict full throttle applications to the highway (it shows no tip-in delay there).

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I have no problem with throttle response but my transmission doesn't grip until about 1000 rpm so if i stomp on it from zero it'll spin up to a really high torque range before grabbing and spin the wheels. It's not an enjoyable jerk. So i have to give it gentle throttle until about 1200 before I "hammer down".

The x5 throttle programming is such the first 30% of motion gives you maybe 10% throttle. Very very different than cable driven throttle and many people hate it there are ways to get that reprogrammed. I'm portioning this out to see if this is what your issue is. It may not be a problem at all with the car just the way it is made.

So: when driving very slow like 5-8 mph over rough terrain, the first 30% of throttle can be used to gently change speed then after 30%, the transfer is more linear.

0-0
10->4
20->7
30->10
40->20
50->35
60->50
70->70

It's not exacty that just an idea.

Light throttle does very little. If you sweep steady through the range it'll feel like there's a delay.

My car right now has a problem with light throttle i have to "start" at 25-30% when engine is cold or it stumbles so i tap the throttle quickly through the first 1/4 of the range. Unless you get you throttle reprogrammed to linear you might have to train around that limitation also

All speculation that might be there issue not saying for sure it is.

https://youtu.be/8NohVmaY134?si=EnGxMd54EbbPAull

See video. Throttle adaptation may be your issue but i thought i saw you addressed that.

I don't remember if you checked fuel pressure but bit it's not impossible that the vent for the regulator is hooked to manifold vacuum which could cause this exact problem. Long shot but just takes a minute to check. ;)

Thanks for this. I did reset adaptations using INPA but I'll try this method as well. I keep wondering if this is how the vehicle came from the factory but I have a hard time believing it. I've driven many makes and models over the years and never had this issue before.

Thanks. Yeah I did verify fuel pressure. 54 psi at the rail with the pump running, 48 psi when the pump stops.

Those pressures are good but the regulator vent hose being hooked to vacuum will lower the engine running pressure so it might be a good idea to have a quick look at that hose.

Is this the small hose that connects to the air intake elbow? Or which hose are you referring to?


I just checked pressures with the engine running and did some deep throttle stabs (in neutral of course), the pressure does bounce a bit as low as 45 psi but quickly recovers, almost instantaneously.

Yeah i think that might be your issue. On my wife's e 53, when the FPR was shot it woukd do that.

After replacing, WOT no load wouldn't move the needle half a psi.

https://youtube.com/shorts/AEjiWbrrP...SWKqNcv3Itf4xm
Before

https://youtube.com/shorts/ctQFEWT6ftU?feature=shared
After

If you are getting 5 psi drop from WOT that's 10% less fuel when engine is demanding most. Can you look at your O₂ sensor real-time to see if at the same time you're getting strong lean burn? I would expect a stumble from 10% drop in fuel.

No misfire or knocks? What about rough running?

The pressure is stable under idle, it doesn't oscillate like that first vid. but it does drop more than the 2nd vid with deep throttle application. Looks like the FPR is inside of the filter in this vehicle?

Interesting you mention knock. The engine does seem to knock quite a bit at lower RPMs But overall it's pretty smooth. I assumed it was VANOs noise because the knock sensors were supposed to activate and prevent knock but now it makes me wonder.

FPR is attached to filter. My case the failure was just the o-ring between the two.

Yes, the hose that comes from the thin metal line coming from underneath, should be going to the intake boot. The fuel pressure should not be dropping (Oscillating means nothing) but it's not really clear about how you are checking the pressure. It would be best to check the pressure under load (and rpm) with fuel gauge taped to the window and driving to rule some things out. At this point though, if you know there has been an update exactly for this problem and the update wasn't done, then maybe lean towards that as well.

I had the fuel pressure gage connected to the service port on the fuel rail and held up by mechanic's wire so I could see it through the windshield, just doing deep stabs of the throttle at idle. Not ideal from a diagnostic perspective but I wouldn't feel safe driving around like this.

My fuel pressure gauge hose is just long enough to feed up to the window and close the hood. That said, you should definitely not see a 5-# drop from a throttle stab in neutral. In my second video I'm doing redline punch to get less than 1psi drop. Any less throttle and it didn't drop 1/2 psi.

I would take apart the FPR and check those two o-ring though i think just the inner one matters. I think the outer one goes to atmosphere. (So would come out to ground)

Somewhere i have a picture showing the size it's like 8mm OD 4mm id but that's mostly guessing.

Throttle tip-in issue/stumble ([emoji2391].0 [emoji2[emoji2391]9[emoji2391]]-speed)
 

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Look at the o-ring. You can immediately tell it will no longer do its job.

8/5 mm very close.

It looks like on my model year the regulator is integrated into the filter, no seals or anything. But I have a new filter+regulator coming to rule this out. So far almost everything on the vehicle has been original so the fuel filter probably is too.

Very few had and still have the separate regulator, anyway if there is a problem it will be with the fuel filter not the regulator. If you would have checked the fuel pressure under load you could have ruled out the pump and filter but not a bad plan to change it if it has never been done.

Agreed. I wish I had a setup (or safe place) I could do this test properly under load.
Although bad fuel filter would also probably affect high power, high RPM operation - no? That's when fuel demand would be the highest. Either way this seems like a maintenance item to rule out.

Exactly, any problem with fuel delivery would show up more under load.

Most likely the off idle tip-in was on the lean side from the factory and even a small amount of carbon build up and engine wear turned out to be a problem which is why there was an update.

You still shouldn't have the pressure drop like you are saying but maybe that has something to with with how you are looking at the gauge ?? And still no codes ??

Combined 2-in-1 replace filter also FPR.

Mine that was serviceable was from 2001. I don't know when they changed.

FPRs "main job"* is tob hide a failing fuel pump. A pump not putting out enough pressure will be hidden due to the FPR regulating the output.

* Tongue in cheek, it's collateral pain in the butt however plenty of times I've seen a weak fuel pump not caught due to FPR hiding the output dropping.

It's too bad can't easily measure psi/flow at the pump output.

I was in similar shoes i replaced the filter and FPR as a unit only after teardown did i realize that the filter tough plenty dirty probably had 200,000 miles left they are huge, and that the small o-ring was toast most likely the cause of my woes.

I never had any codes or even lean warning just very very hard starts occasionally.

Wife never hit that car hard WOT so the weak psi full throttle never caused a problem driving.

FPR/filter is a maintenance thing ay this age. I didn't see if you replaced the pump but do some math:

Odometer in miles divide by average speed in mph. That will show you estimate of hours.

If using ethanol gas you should get about 5000 hours, pure gas 4000 hours.

In mine and wife's case it was very close.

132000/27=4888.889 was one of them the other was crazy close.

Hope you find and resolve. I wished my 3.0 was three pedal would be much more responsive.

Okay, so I've managed to do a few things:

• changed the fuel filter and regulator with a Hengst branded one
• replaced the throttle body with a new OE (VDO/Continental) one. I found one on clearance at Rockauto so went ahead and did it.
• Did a visual boroscope inspection of both catalysts through the O2 sensor ports to see if they were clogged. Not obviously melted or anything.

Unfortunately the problem persists. It's hard to diagnose anything through INPA because the refresh rate is so low it totally hides transient issues like this one. Are there faster/better monitoring or logging options? I'm running out of things to try. I could go ahead and put a new fuel pump on since the original is probably on borrowed time and it's not that expensive or hard to do.

Will try to get the software update next week.

Would you please test fuel pressure after the Hengst installation? There was a bad batch of Hengst fuel pressure regulators (installed in filter) and I had one on my E39. It generated fuel pressure of 60psi causing the car to to run rich.

It’s common for the filler/FPR to mask low output fuel pump. Did you ever estimate your engine on hours?

My money is on weak fuel pump.

Sadly a real pita to test there's no test port. You have to add in a T between the pump and filter (though not difficult if you have the under belly off from filter change)

That's pretty much all wrong andrewynn.
The filter and regulator can't mask a bad fuel pump, the test port is on the rail, that's the part that counts. Testing (pressure) between the pump and filter only would only give an indication of restriction (plugged fuel filter.) Testing at the rail and under load eliminates fuel supply as being a problem.

I have a new fuel pump on order, I figured this would be a reliability improvement if nothing else. I also pulled some data using BMW Logger (attached) if anyone of ya'll have used it. The area of interest to me is between 31 sec and 33 sec where a hard stumble was experienced. Notice the lag between throttle application (light green line, TPS) and any rise in RPM (dark green line).


https://xoutpost.com/data:image/png;...AAAElFTkSuQmCC

Another long shot you could try is to check the connectors in the E-Box but you should really look at getting that firmware update.

My X5 5-speed does the exact same thing. I've never tried to fix it because I know the cause and I've just never felt it worth the trouble to fix it. It's the off idle tip-in map.

I've had two e30s that did this exact same thing in the past. The first car was just an eta and it drove me crazy. I figured it was just an old car and running bad. When it was wrecked, I bought an "i" car and used the tranny from the eta to make the newer one a 5-speed. It had the same off-idle problem so I knew it was a BMW thing. I turbo'd it and put in big injectors, so I was forced to remap it. I used a Moates eeprom emulator and free software (I don't remember the name). But the definition file called the map "throttle enrichment" or something like that. Once I fixed that map, it was smooth as silk.

I'm pretty sure that BMW kept that map super leam to meet EPA regulations. Seeing as how there are so few 5-speed X5s out there, I figure the complaint level was fairly low. After the maintenance issues I had with a lowered, boosted e30, I had no desire to f-@k with my X5. I just want it to go long periods without breaking down any more. I hate sitting on the side of the road.

That's disturbing if this is how it was when new! I've had lots of different makes and models with 5-speeds (mostly non-premium brands like Chevy and Honda) and never had any gripes like this. Can you elaborate on how the remap would be done? Edit: Looks like there's a sort-of how to on the E46 forum: https://www.e46fanatics.com/threads/...uning.1082287/


I dug deep into EEPROM programming and remapping on a Fiero years ago but that was because it was a custom job with a different engine and computer.


@80stech - I do still plan on getting the firmware update. It's just hard to find time to get to the dealer.

I haven't remapped anything in about 10 years and I did the e30 about 15 years ago but... the bin file is on eprom or eeprom. You have to remove that chip and replace it with something that has your custom information on it. Moates (i'm not sure if they still exist) was big into Ford Mustang programming. One of their products was an eprom emulator that took a usb cable. You would go online and get a bin dump for your model and a definition file for the same. The definition file separated the 1's and 0's into maps that could be changed. You could then write your new bin to the emulator and plug the emulator into the socket where you removed the eprom from. You could then make changes on the fly if you kept a laptop in the car.

There may be better ways now, but I doubt it on an e53.

There is.. Active Autowerk. But it’s going to cost.

https://store.activeautowerke.com/pr...iant=780147815


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

Moates is still there. The Ostrich is the emulator that I used. It's $175.00. The software TunerproRT. It's $39.00 for the pro version. I don't remember what the $$ gets you, I think it was just a splash screen, but it's good software. Well worth the $39.00.

You can do a search for e53 bin files and Tunerpro definition files for the e53 and you should be able to find a rabbit hole pretty easily that will keep you up past your bedtime.

Oh man.. How many times have I been here! LoL… :yawn:


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

Any recollection what the table name was? Now that i'm in TunerPro there are approximately 5 billion tables, many without good descriptions or titles. Did you end up just increasing the values in the table incrementally to smooth it out?


Edit: Are they these tables? These are for warm engine. There are three additional for cold engine.

• ip_tco_2_pl_ivvt_1__n__maf (Injection time used for bank 1 during part load. Warm engine)
• ip_tco_2_pl_ivvt_2__n__maf (Injection time used for bank 2 during part load. Warm engine)
• ip_ti_tco_2_is_ivvt__n__maf (Injection time used during idle. Warm engine)

These also sound possible:

• ip_tib__n__maf (Basic injection time)
• ip_ti_wup__n__maf (Warm up correction for injection time)

Edit 2: Found some documentation on the MS4X website about "Tip-In Enrichment / Cylinder Rewetting" with the note at the end, "Applying 5% steps to the whole table ip_ti_pvs__pvs__n in either direction shows good results". I'm probably going to try tweaking this table and see what happens.


I also got a copy of TSB B 12 39 06 (which supercedes B12 204 04) and it only applies to production dates 10/3 - 10/4. Mine was built 09/3 and therefore the bulletin doesn't apply.

Here goes the rabbit hole...found another thing that might do it:

• Anti-jerk "_AJ_" retards ignition during rapid throttle opening to smooth out torque (can be removed by increasing c_tco_min_aj to 142.5C).

I was surprised how easy it was to upload the new maps to the car using MS4X. Was expecting some errors and troubleshooting but it worked right away.


For the record, I did go ahead and replace the fuel pump with a new Carter unit. It seems "somewhat better" (although I've learned that when a problem isn't totally fixed, any improvement is usually a placebo).

Does the pressure stay the same when hitting the throttle? After i replaced FPR the rail pressure was constant no matter what.

Yes, I did check it after the FPR was replaced and it was completely steady.

Another work around you could try is to pull up/down with a resistor the air charge temp sensor in the intake to make it look like the air is a bit cooler than it really is. The DME looks at that for "tip in" fuel amount. That being said I finally got my temp gauge problem fixed by cleaning the connector in the E-box, I might be imagining it but my tip-in throttle response seems better too!

Just to follow up on this - it's hard to tell if it's 100% "fixed" because I don't know what it was designed to feel like when new, but it feels about 80% better and overall I'm happy with it.

To recap:

• The elusive TSB didn't actually apply to my build date, so no luck there.
• In addition to the maintenance items throughout this thread, I increased the throttle tip-in fuel map "ip_ti_pvs__pvs__n" by 10% across the low-throttle regime <= 2200 RPM and 5% across the mid- to high-throttle regime <= 2200 RPM using TunerPro (the tuning software) and MS43X (the software to transfer the data back and forth to the car's DME). I intended to do an adjustment of 5% only, but the minimum increment is larger than this (something to do with the table entries being stored as 8-bit values).
• I also disabled the anti-jerk feature, which retards timing on throttle tip-in to supposedly smooth things out, by setting c_tco_min_aj to 142.5C. This means at any engine temp below 142.5C, the feature is turned off (and the engine would never reach this temperature without self-destruction).

It seems a bit ridiculous to resort to tuning to solve an issue like this on a 100% stock BMW but it was easy enough to try and seems to help. The only rationale that makes sense to me is what is explained on the MS43X wiki: The throttle tip-in fuel is extra fuel designed to wet the cylinder surfaces.
With age and carbon build up the surface area of the cylinder may have increased. :dunno:

I think what you are describing as "throttle tip-in" I have referred to as "throttle pumps," which is when you dump a bit of extra fuel in when the throttle is being opened rapidly. I don't think it is for wetting the cylinder (indeed that sounds like something which is undesirable) but rather because the air mass flow meter doesn't measure as quickly as the air starts moving, so you have to add in some fuel before the airflow meter is really telling you that it needs it. I might be wrong here, I am not an expert.

Pretty rad we have an E53 tuner on the forum. :2thumbs:


E53 RiPPeR
XOuTPoST jUNkiE
ReVELaTiON 22:21

I'm also not an expert by any means, but before you could atomize the fuel you'd have to wet the surfaces, right? i.e. there's a certain amount of fuel that condenses on the cylinder walls and piston top and doesn't contribute to the A/F of the ignitable mixture?

Not sure I'd call myself a tuner, but glad you think so! If there's any interest I'll put together a how-to on getting started (how to set things up and connect, etc).

No, fuel will only burn once it has vaporized. It may land on the surface of the piston and walls but it vaporizes before it can burn. If there is any liquid fuel left when the flame ignites, the liquid fuel evaporates before it starts to burn.


The point of any kind of fuel injection (whether electronic or plain old carburetors) is to first meter in the exactly right amount of fuel, and second to vaporize it completely. I'm guessing that statement from the manual was just incorrect, or was talking about something else.