E46 BMW Social Directory E46 FAQ 3-Series Discussion Forums BMW Photo Gallery BMW 3-Series Technical Information E46 Fanatics - The Ultimate BMW Resource BMW Vendors General E46 Forum The Tire Rack's Tire Wheel Forum Forced Induction Forum The Off-Topic The E46 BMW Showroom For Sale, For Trade or Wanting to Buy

Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

Go Back   E46Fanatics > E46 BMW > General E46 Forum

General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

Reply
 
Thread Tools Search this Thread Rating: Thread Rating: 1 votes, 3.00 average. Display Modes
Old 09-07-2012, 10:14 AM   #21
alexxander.foster
Registered User
 
Join Date: May 2008
Location: San Francisco, CA
Posts: 171
My Ride: 2000 323i
Ah, gotcha! Well, thank you. I'm glad it might help someone And I completely agree on not being able to blow much smoke in one puff. Its funny you should say so, but I'm actually a pretty small guy. I've tried to use my breath to to do various repairs and I get really light headed really quickly. Its this reason I'm building a machine for my vacuum leak testing. I figured looking for an EVAP leak while not fatigued would be a good idea for me.

Quote:
Originally Posted by dmax View Post
Not listen...look for smoke coming out.

You might be a large guy, but I doubt you can blow enough smoke in one puff to fill the intake side and all the vac lines with smoke and enough pressure for it to come out...thus I think that check valve idea of yours is a great one.
I've been thinking about that too. I just thoroughly inspected it three months ago but who knows. I'll take another closer look at it once the chaos of school dies down a bit.

Regarding shifting, I agree. And if I were driving on flat land I would just downshift. But seriously, between the traffic, the hills, and the suicidal/entitled pedestrians in SF, I need the entire RPM range (... I need it begrudgingly). The car drives more-or-less normal on flat roads. You can still tell there's a problem but its not nearly as exaggerated. But in the hills of SF it doesn't drive properly. It didn't have these problems when I first moved to SF and its been getting progressively worse.

Quote:
Originally Posted by dknightd View Post
My guess, repeat guess, is a torn intake boot. Let us know what you find solves your problem.

btw, I think your engine would be happier if you downshifted. 12-1500 is a little low for significant throttle.
Hey Mark, thanks for the suggestion. I've been actually thinking about that possibility too. I left a cam sensor disconnected a few years ago and it had very similar but more extreme symptoms. I'll put that on my check list.

Quote:
Originally Posted by megamax View Post
I had a very similar problem many years ago, except my car would completely stall when making a turn (intermittently). I never had a problem on hills though.

The dealer replaced a bad cam position sensor, and the problem went away. Frankly, I have no idea of the relationship between the sensor and turning, but I figured I'd share my experience.

Mark
Hey helomech, thats a bummer about the fuel pump. But it sounds to me like the CCV system is a good next step. If you're planning on just replacing parts instead of diagnosing a singular problem, then I would add one of the intake boots to your list of goodies. That part seems to go bad quite often on BMWs.

Its possible that sfcjetjr is right and this is a multi-faceted problem. The fuel pump might have been a part of the issue and theres still another problem pending. Multiple problems would also explain why only a couple people have stepped forward and there are no resources on this online.

I havent done anything yet with my car since posting so I should be able to get a good baseline and I'll document it. I likely wont replace parts until I determine definitively whats wrong.

Quote:
Originally Posted by helomech View Post
Update: Replaced fuel pump yesterday and it didn't solve the problem. I do have better throttle response though and it's a cheap and easy install, so might as well do it. If yours is the original, just make sure you have small hose clamps to replace the crimped on factory clamp that you must cut to remove. I found a pump on Amazon for only $98. I didn't buy OEM because I don't plan on having the car more than another 20K. I found some gunk in the valve cover vent, so I will replace the CCV system soon. Bavauto.com sells the improvement kit for only $180 and they provide a nice DIY video.
alexxander.foster is offline   Reply With Quote
Old 09-07-2012, 10:43 AM   #22
helomech
Registered User
 
Join Date: Feb 2012
Location: California
Posts: 28
My Ride: 2000 323i
My intake boot is in great condition. I inspected all that stuff recently. I just need to find the time to perform extensive troubleshooting. I also read somewhere that the transmission software could use an update that a dealer can perform.
helomech is offline   Reply With Quote
Old 09-20-2012, 01:02 PM   #23
alexxander.foster
Registered User
 
Join Date: May 2008
Location: San Francisco, CA
Posts: 171
My Ride: 2000 323i
Today I broke out my generic OBDII scanner and monitored the engine data for a while. I was looking for adjustments in the LTFT and STFT. Everything seemed pretty reasonable. LTFT values are +0.7% for both banks. The STFT values were higher at around +4.0% but considering it was cold out I dont think thats unusual. What surprised me was the reading for the O2 sensor. Bank 1 was switching between ~100mV and ~900mV but bank 2 was almost pinned at 750mV. So I could have either a short in the O2 sensor circuit, a short in the physical O2 sensor, or a faulty ground to the intake manifold (highly unlikely). This is also pretty consistent with significant power loss and other such drivability issue.

Admittedly, my scanner does not have the worlds fastest processor so data is coming in VERY slowly. Its possible that the switch frequency of my bank 2 O2 sensor is lining up with my scanner's refresh rate. I'll give it a little bit of time then look at the data again.

Any thoughts anybody?
alexxander.foster is offline   Reply With Quote
Old 09-22-2012, 04:42 PM   #24
alexxander.foster
Registered User
 
Join Date: May 2008
Location: San Francisco, CA
Posts: 171
My Ride: 2000 323i
New development:

Okay, I FINALLY got a chance to pick up a fuel pressure tester. The results are all within spec per the Bentley manual:

Expected fuel pressure range:
min: 47.68psi
max: 53.66psi

Measured range under normal load and idle conditions:
min: 52.25psi
max: 52.75psi

Measured range under rapid RPM increase/decrease:
min: 50.50psi
max: 51.50psi

The fuel pressure was extremely stable throughout the entire RPM range. I also waited 20min after shutting the car off to verify the fuel pump check valve holds and none of the injectors are leaking. It holds. I could probably use a new fuel filter (40k miles since the last replacement).

My conclusion: the fuel system appears to be operating just fine. I suppose I could buy a hose extension so I can test the fuel pressure while I'm driving. Perhaps the problem develops when the engine is loaded with the weight of the car. Suggestions are welcome.
alexxander.foster is offline   Reply With Quote
Old 09-23-2012, 06:42 PM   #25
alexxander.foster
Registered User
 
Join Date: May 2008
Location: San Francisco, CA
Posts: 171
My Ride: 2000 323i
Okay, looks like I'm just documenting at this point for future reference.

I had a friend help me feel out the problem yesterday afternoon. After finding a "sweet spot" that we could replicate the problem repeatedly, we both agreed that its NOT engine related, but instead drivetrain related. We found that when the engine was under a heavy torque load such as low RPMs, something in the driveline would shift or move which ate up some forward rotation.

We took off the heat shielding and took a look at the whole driveline while the car was on jacks. We subjected the car to various rapid loading and unloading by dumping the clutch. We found three things that are possible culprits:
- Engine mounts
- Passenger-side rear outer upper control arm
- Driveshaft center bearing

The engine mounts are brand new, but appear to be defective. Without considerable effort the whole engine can be moved quite a bit. My friend was able to compress or expand the engine mounts a full inch just by rocking it. The passenger side rear outer upper control arm bolt was loose. This could have been part of the problem since its a suspension component for the drive wheel, but I doubt it. We'll see over the next few days if it repeats. Lastly, the drive shaft center bearing is a very likely culprit. The bearing itself had a lot of play and rattle. The rubber housing seemed like it was in good shape, but I'm not sure how much deflection is tolerable.

My new theory is its the driveshaft center bearing. Perhaps under high torque situations, turns, or hills, the rubber housing is unable to keep the driveshaft centered, and causes the u-joint near the center bearing to push off to the side and absorb some forward motion in the process. What a pain in the ass.
alexxander.foster is offline   Reply With Quote
Old 10-05-2012, 02:15 PM   #26
alexxander.foster
Registered User
 
Join Date: May 2008
Location: San Francisco, CA
Posts: 171
My Ride: 2000 323i
Last Update:

Okay, the problem finally got bad enough to reveal its root cause. My clutch is going out. I burned the flywheel and the clutch bad enough to cause momentary slipping under heavy torque, but under normal operation the clutch grips just fine. Additionally, I damaged the spring mechanisms in the dual mass flywheel, which has created an increased driveline slop.

Don't ask me how I confused an engine issue or drivetrain issue with a failing clutch, I'm kinda disappointed in myself since I was so far off. I guess I hadn't even considered it since the clutch and flywheel only have 40k on it. Perhaps the dual mass flywheel played a part in masking the problem (this is my first car with a DMF). *palm to forehead*
alexxander.foster is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Censor is ON





All times are GMT -5. The time now is 04:32 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
(c) 1999 - 2011 performanceIX Inc - privacy policy - terms of use