surging feeling

[krunchnkevin]

I have a 2004 BMW 330i with 55,000 miles on it. The problem I've been experiencing is a jerking or surging feeling while giving it plenty of throttle in the power band. It doesnt happen right away, it happens when I've been in the throttle for a while.
From 0 to 80, with the throttle at about 75%, I feel a surging feeling in the entire car at about 50 or 60 MPH. Conversely, If I accelerate from 50 to 100 MPH, I feel it start to surge around 80 MPH.
The seat of my pants tells me it's something to do with fuel. But, no warnings or codes are coming up. Before I just go replacing anything fuel related (fuel pump, injectors, etc.), is there anything I should point towards first?

[telijah]

"Surging" feeling? Like, does the car start accelerating quicker when surging? Also, is it auto or manual? How long have you owned the car? The car has a VANOS system which, after a certain RPM and under heavy throttle, you're gonna feel the car pull just slightly harder...

Edit: If you know what VANOS is, then sorry, I wasn't trying to insult intelligence.

[krunchnkevin]

Maybe surging wasn't the right term. It's more of a pulse. You know that great "seat of your pants" feeling that you get when you gently put your foot to the floor and watch the odometer methodically rise and you can really feel the car push you back in your seat? Well, when it starts to pulse or surge it feels like your letting your foot off of the gas and then putting it back on, only its at a rhythm of about 200 beats a minute and very methodical. The car will continue to gain speed, just not at the same rate.
It's far below the red line so it shouldn't be a rev limiter.
I've owned the car for 8 months and its only done this for the last 2 months.

Thanks for the reply.

[kgvickers]

Subscribed.

I've got a similar problem. An indie tech thinks it's the MAF sensor. I've not had a chance to troubleshoot yet.

[ZHP]

I'll second the MAF theory.

[Brian328i]

Wow that was somewhat confusing to read and understand. But I think what you mean is that lets say your at 2500 rpm and you press the gas the increase in rpms isnt linear? Like it dips off a bit and then picks up again and then dips off and picks up... till about high 4000's even 5000 and then its more linear? If so check your air intake boots leading from the MAF to the throttle body especially at the joints sqeeze the boots and look for hair line cracks, check were the ICV connects to the boot that place is has very thin rubber and holes are often found there.

If you do have holes or even cracks of any kind change out the two boots, about 40 bucks, and while its all apart clean the ICV valve out with either brake cleaner or MAF sensor cleaner. That should clear everything right up.

Oh and also is the check engine light on? Did you get any codes off the car, when I had this problem and as it got to the point where the boots were falling off the car it would end up missfiring.

[telijah]

Got it, so it seems like it's pulsing. I agree on checking what codes, if any, you are throwing first. If no codes, you really need a good indy shop to diagnose it properly. A problem as this could be ignition, fuel, or any number of sensors going wrong and you'll end up throwing a ton of money at it before finding the root cause...

[krunchnkevin]

Thanks everyone! I'm going to check the air intake boots, like Brian328i said. If they look good, I'm going to bite the bullet and take it in. I'll let you know.

[Rob24857]

Won't it be the VANOS unit doing that?

[krunchnkevin]

If it was the VANOS unit, would I get any error codes? Because, so far I havent seen any warning lights / codes trip.

[Brian328i]

If it was the VANOS unit, would I get any error codes? Because, so far I havent seen any warning lights / codes trip.

Ya it should give out codes, depending how bad the VANOS is, from my understanding the pistons inside get jammed a little which causes problems and in turn puts off the CEL. I'm willing to bet that your getting a misfire on a cylinder, but that should also give you codes. Did you try just plugging in a OBDII reader just for the fun of it to see if anything comes out?

[mgraziani]

I have a noticeable stutter at around 2700-2900 RPM's when accelerating hard. It seems to happen in all gears except 1st.
Another forum member said that his similar problem was solved with a DME reprogram at the dealership for about $250.

[saBMW328i99]

Old thread but I had the same thing on my car, accept in my case it was the suppressors. They were'nt firing correctly, in essence the car did not run on all its cylinders.
Replaced it with 2nd hand suppressors and car ran smoothly.

[TKWBMW]

I know this was a old discussion but I was wondering if the problem was ever resolved by krunchnkevin.

I have 55,000kms on my 2004 330i with the M Performance Package and it has been surging (it sometimes feels like a miss rather than long period hesitation) for the past three months. I've replaced the O2 sensor, tried a gasoline treatment and checked the diagnostics. No codes have appeared. The surging seems to be worsening.

Initially I thought it was only occurring in higher gears (I have an auto transmission) with a slight load (going on an inclined "on" ramp,for example) but it was happening at lower gears as well. The torque at lower gears masked the surging.

Any help would be appreciated. Thanks!

[TKWBMW]

Thanks everyone! I'm going to check the air intake boots, like Brian328i said. If they look good, I'm going to bite the bullet and take it in. I'll let you know.

I was wondering if this problem was ever resolved - it sounds very much like the problem I'm experiencing with my 2004 330i.

[rowdy lee]

Anyone have this problem who also has a new fuel filter?

Just am curious...

[krunchnkevin]

Well, I still have the problem and it's slowly getting worse. I took the car into the dealer and they found a crack in an air intake boot. They fixed it and it no longer has a high pitch whine. But, the surging is still there. They told me there were no codes and they couldn't recreate the problem.
I wish I could explain the problem better. The only other way to explain it is along with the surging the engine doesn't sound smooth through the RPM range, it kinda sounds like a sewing machine with the wobble sound.

[TKWBMW]

My 2004 330i with the M package also had the surge/miss in the RPM range when accelerating under a slight load. It wasn't resolved after a new O2 sensor was installed. No codes were generated. I kept driving it with the surge until the Check Engine light finally came on and generated a code. I took it back to the dealer and they updated the software. The problem was resolved after that (and $250 later). My guess is if you can get them to update your software, it will fix the surging problem. It's been 4 months and no sign of the problem.

[slvrXI]

what RPM? Service Bulletin was issued about E46 having hesitation on acceleration in RPM ranging from 4-5k...

[danewilson77]

Thanks everyone! I'm going to check the air intake boots, like Brian328i said. If they look good, I'm going to bite the bullet and take it in. I'll let you know.

What happened to this post here, where you said YOU were going to check the intake boot? Why didn't you check it?

[TKWBMW]

The RPM range was 2500 to 2800. If you accelerate beyond that, it was smooth.

[krunchnkevin]

danewilson77, I took it in for a scheduled maintenance and got lazy. So, I had them check it.
2500 to 2800 is where it surges for me too. How do I get the dealer to update the software, just tell them to do it? I don't want to sound like an idiot when I go in.

[TKWBMW]

Dealers have this natural tendency to dismiss information obtained from "amateurs" on the web so I can appreciate your concern. I brought some of the responses from this forum and others about this problem and showed them the detail that was presented. I also suggested that they come out for a test drive with me if they're concerned that they can't reproduce the symptom. I'm sure you can get it to happen on a pre-tested specific route.

The advantage I had when I took it in was it had finally generated a code that they could check. The dealer didn't argue - in fact, they seemed to already know that a program update was a solution.

Your other alternative is to request the program update and pay for it. As long as you're paying for it, there's no reason they would refuse. All you have to do is have faith that it is the solution. Good luck!

[balidawg]

Bumping this old thread for future readers. This sounds like the infamous 2800 RPM stutter on E46 with MS45.1 DME. See this thread for details.
https://forum.e46fanatics.com/showthread.php?t=966614

I can remotely update your DME software to the latest for free. Hit the link below and read post #1 for what is involved.
https://forum.e46fanatics.com/showthread.php?t=1081716