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  #1  
Old 03-20-2018, 02:01 PM
denigu denigu is offline
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Strange engine issue 2007 335i n54

Hello all. I'm having a "not so serious" issue with my car. When I'm going over 50-60 miles, when Im not accelerating or slowing down and keeping a steady speed, the car kind of increases the rev and comes back to normal every 1-2 seconds. It is like the car wants to speed up but realizes that I am trying to keep a steady speed and gives up. This happens every 1-2 seconds when I'm trying to keep a steady speed. When I'm accelerating, no problem.

Do you guys have any idea what might be the issue with my car?
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  #2  
Old 03-21-2018, 05:37 AM
CALWATERBOY TRE's Avatar
CALWATERBOY TRE CALWATERBOY TRE is offline
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Mein Auto: E93 335i, somewhat mod
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#1 First Thing To Do ---> delete error codes --> drive until prob occurs --> [read codes] --> post here!
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  #3  
Old 03-21-2018, 06:52 AM
gbalthrop gbalthrop is offline
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Mein Auto: 2007 328xi E91
Quote:
Originally Posted by denigu View Post
... When I'm going over 50-60 miles, when Im not accelerating or slowing down and keeping a steady speed, the car kind of increases the rev and comes back to normal every 1-2 seconds. It is like the car wants to speed up but realizes that I am trying to keep a steady speed and gives up. This happens every 1-2 seconds when I'm trying to keep a steady speed. When I'm accelerating, no problem.
If that happens on open highway where it is safe to hold a steady speed & no other traffic, carefully note the exact vehicle speed, and approximate accelerator pedal position. Then, at that same speed, set cruise control, remove your foot from the accelerator pedal and see if the problem goes away. Increase speed several MPH and retest. Decrease speed several MPH below original speed & retest.

If the problem does NOT occur when cruise control is operating, the problem is likely a failing potentiometer/sensor in your accelerator pedal module. If you have INPA/ISTA, you can test for jumps or gaps in the module sensor output voltage as you slowly press the pedal with the engine off but ignition on.

Like CWBTre (Formerly CWBDue ;-) says, read & record ALL codes, CLEAR those codes, and if problem recurs, read/record codes again. Let us know what codes you get, particularly looking for anything related to VVT or Accelerator Pedal Module.

George
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Old 03-21-2018, 09:36 AM
denigu denigu is offline
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Quote:
Originally Posted by gbalthrop View Post
If that happens on open highway where it is safe to hold a steady speed & no other traffic, carefully note the exact vehicle speed, and approximate accelerator pedal position. Then, at that same speed, set cruise control, remove your foot from the accelerator pedal and see if the problem goes away. Increase speed several MPH and retest. Decrease speed several MPH below original speed & retest.

If the problem does NOT occur when cruise control is operating, the problem is likely a failing potentiometer/sensor in your accelerator pedal module. If you have INPA/ISTA, you can test for jumps or gaps in the module sensor output voltage as you slowly press the pedal with the engine off but ignition on.

Like CWBTre (Formerly CWBDue ;-) says, read & record ALL codes, CLEAR those codes, and if problem recurs, read/record codes again. Let us know what codes you get, particularly looking for anything related to VVT or Accelerator Pedal Module.

George
Thank you for your response. Same issue with cruise control. I dont get any codes.
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  #5  
Old 03-21-2018, 01:30 PM
gbalthrop gbalthrop is offline
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Mein Auto: 2007 328xi E91
Quote:
Originally Posted by denigu View Post
Same issue with cruise control. I dont get any codes.
What are you using to read codes?
Do you have a laptop?
Are you familiar with INPA/ISTA?
When Cruising on level highway at 60-65 with Cruise control ON, does it ALWAYS speed up and then slow back to the set speed?
Does it sometimes slow first and then speed back up to set speed?
Does it ever either speed or slow above/below set speed and NOT return to set speed?

If what you are experiencing is a momentary speed-up by ~ one MPH followed by a slowing, which then repeats, that sounds like a fault in a sensor signal to the DME. Since the speed fluctuation occurs whether in cruise control or normal operation using accelerator pedal (without moving the pedal), then perhaps the issue is the ESS (Eccentric Shaft Sensor) signal, which could be due to either a failing sensor or a dirty/oily connector. This is particularly true if the issue ONLY appears at speeds above ~ 55MPH where the Eccentric Shaft is in a "higher valve lift" position.

INPA/ISTA which you can download and install on a laptop and connect to your car via a K+DCAN cable for ~$45 from BimmerGeeks can read signals in real time from your ESS, and other sensors such as Accelerator Pedal Module potentiometers, and getting all the electronic diagnostics you can will reduce "parts throwing" to try to fix an unidentified cause of the issue. BTW, an oil leak at the ESS can indicate a failing ESS.

Also, since you have one or more oil leaks: "I refill my oil every other week, it is leaking like crazy" you stated in your other recent thread, I would suggest the following:

1) With a digital camera in hand, remove the Top Engine Cover or Coil Cover and take photos of the entire perimeter of the Valve Cover gasket area (all the way around the cover);
2) Take photos of the ESS and its gasket after removing the connector on the right front of the Valve Cover.
3) Take photos of the VVT Actuator Motor and the gasket area where the motor attaches to the Valve Cover.
4) Take photos of the OFHG (Oil Filter Housing Gasket).

You do NOT state/quantify how much oil per 1000 miles you are having to add, but a leaking oil pan gasket generally just "seeps" oil at a slow rate of loss, and is more of a nuisance than anything else. If you are having to add a quart of oil every 1000 miles or so, you have a serious problem that needs identifying. You say you have put ~7,000 miles on the car since you got it (~ 6 months ago?) -- how much oil have you added since purchase? Have you changed the oil since purchase? How much oil was drained?

Attach several of those photos (beginning with the ESS) to a post and someone can help you get a better idea of what REALLY needs to be addressed with your car.

Since your splash shield/lower engine cover is missing, you can easily check for the location & amount of any oil leaks by simply putting a large piece of cardboard under the vehicle after hot shutdown. Carefully note the position (Left/Right/Front/Rear) relative to the engine of any drips/puddles. Then get the front wheels on ramps, take e-photos, clean oily areas thoroughly, run on dry road, and repeat.

I would START with reading about how the "fly by wire" throttle works on your 335i, and (if you do NOT already know this) learning how engine load (acceleration/deceleration) is NOT controlled by a butterfly in the throttle body, but by intake valve lift, controlled by the VVT (Valvetronic) system.

NO car that is 11-years-old is going to be trouble-free, and the 335i with twin turbo is LESS trouble-free than most normally-aspirated-engined vehicles. Unless you want to/can spend $3k per year on repairs & maintenance in the next 3 years, DIY is your ONLY OUT. NEED TO RTFM, Bentley that is:
http://www.georgebelton.com/335i.tech/bentley.php

Also there is LOTS of info in TIS:
https://www.newtis.info/tisv2/a/en/e92-335i-cou/

I hope you already know this, but the two quickest ways to RUIN an engine are:
1) Run it low on Oil;
2) Run it low on Coolant.

Coolant hoses you identified, ramps, & socket sets can be bought for ~$200 total. Gaskets are likewise cheap. Knowledge & labor are priceless. You need your own, or you will either pay exorbitantly for someone else's or rue the day you didn't.

George
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  #6  
Old 03-21-2018, 02:05 PM
denigu denigu is offline
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Location: binghamton
 
Join Date: Jul 2017
Posts: 25
Mein Auto: nothing :(
Quote:
Originally Posted by gbalthrop View Post
What are you using to read codes?
Do you have a laptop?
Are you familiar with INPA/ISTA?
When Cruising on level highway at 60-65 with Cruise control ON, does it ALWAYS speed up and then slow back to the set speed?
Does it sometimes slow first and then speed back up to set speed?
Does it ever either speed or slow above/below set speed and NOT return to set speed?

If what you are experiencing is a momentary speed-up by ~ one MPH followed by a slowing, which then repeats, that sounds like a fault in a sensor signal to the DME. Since the speed fluctuation occurs whether in cruise control or normal operation using accelerator pedal (without moving the pedal), then perhaps the issue is the ESS (Eccentric Shaft Sensor) signal, which could be due to either a failing sensor or a dirty/oily connector. This is particularly true if the issue ONLY appears at speeds above ~ 55MPH where the Eccentric Shaft is in a "higher valve lift" position.

INPA/ISTA which you can download and install on a laptop and connect to your car via a K+DCAN cable for ~$45 from BimmerGeeks can read signals in real time from your ESS, and other sensors such as Accelerator Pedal Module potentiometers, and getting all the electronic diagnostics you can will reduce "parts throwing" to try to fix an unidentified cause of the issue. BTW, an oil leak at the ESS can indicate a failing ESS.

Also, since you have one or more oil leaks: "I refill my oil every other week, it is leaking like crazy" you stated in your other recent thread, I would suggest the following:

1) With a digital camera in hand, remove the Top Engine Cover or Coil Cover and take photos of the entire perimeter of the Valve Cover gasket area (all the way around the cover);
2) Take photos of the ESS and its gasket after removing the connector on the right front of the Valve Cover.
3) Take photos of the VVT Actuator Motor and the gasket area where the motor attaches to the Valve Cover.
4) Take photos of the OFHG (Oil Filter Housing Gasket).

You do NOT state/quantify how much oil per 1000 miles you are having to add, but a leaking oil pan gasket generally just "seeps" oil at a slow rate of loss, and is more of a nuisance than anything else. If you are having to add a quart of oil every 1000 miles or so, you have a serious problem that needs identifying. You say you have put ~7,000 miles on the car since you got it (~ 6 months ago?) -- how much oil have you added since purchase? Have you changed the oil since purchase? How much oil was drained?

Attach several of those photos (beginning with the ESS) to a post and someone can help you get a better idea of what REALLY needs to be addressed with your car.

Since your splash shield/lower engine cover is missing, you can easily check for the location & amount of any oil leaks by simply putting a large piece of cardboard under the vehicle after hot shutdown. Carefully note the position (Left/Right/Front/Rear) relative to the engine of any drips/puddles. Then get the front wheels on ramps, take e-photos, clean oily areas thoroughly, run on dry road, and repeat.

I would START with reading about how the "fly by wire" throttle works on your 335i, and (if you do NOT already know this) learning how engine load (acceleration/deceleration) is NOT controlled by a butterfly in the throttle body, but by intake valve lift, controlled by the VVT (Valvetronic) system.

NO car that is 11-years-old is going to be trouble-free, and the 335i with twin turbo is LESS trouble-free than most normally-aspirated-engined vehicles. Unless you want to/can spend $3k per year on repairs & maintenance in the next 3 years, DIY is your ONLY OUT. NEED TO RTFM, Bentley that is:
http://www.georgebelton.com/335i.tech/bentley.php

Also there is LOTS of info in TIS:
https://www.newtis.info/tisv2/a/en/e92-335i-cou/

I hope you already know this, but the two quickest ways to RUIN an engine are:
1) Run it low on Oil;
2) Run it low on Coolant.

Coolant hoses you identified, ramps, & socket sets can be bought for ~$200 total. Gaskets are likewise cheap. Knowledge & labor are priceless. You need your own, or you will either pay exorbitantly for someone else's or rue the day you didn't.

George

Thank you so much for your help George. I dont feel like I dont know anything anymore. I was only reading codes with a friend's regular old port device for cars. I just purchased a cable to run that program.

When Cruising on level highway at 60-65 with Cruise control ON, does it ALWAYS speed up and then slow back to the set speed? Does it sometimes slow first and then speed back up to set speed? Does it ever either speed or slow above/below set speed and NOT return to set speed?
Not always but %80 of the time. It always speeds up and return back, not the other way. It always returns to set speed.

So will the diagnostics show what is causing this issue? Or does a professional needs to look at data the car is showing to identify the issue?

I will take photos and post them here. So you're right I drove the car 7,000 miles and bought it 6 months ago. I used approximately 13 quarts of oil.

Do you think I will be able to break the engine down and replace these parts on my own? I am willing to spend days working on the car, but I'm not sure which tools I'm going to need. Are ramps enough to let me do whatever is needed to be done on the engine?
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  #7  
Old 03-21-2018, 10:25 PM
gbalthrop gbalthrop is offline
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Mein Auto: 2007 328xi E91
TO DIY, OR NOT TO DIY, THAT is the Question ;-)

Quote:
Originally Posted by denigu View Post
...I just purchased a cable to run that program...So will the diagnostics show what is causing this issue? Or does a professional needs to look at data the car is showing to identify the issue? I will take photos and post them here. So you're right I drove the car 7,000 miles and bought it 6 months ago. I used approximately 13 quarts of oil.

Do you think I will be able to break the engine down and replace these parts on my own? I am willing to spend days working on the car, but I'm not sure which tools I'm going to need. Are ramps enough to let me do whatever is needed to be done on the engine?
Suggested Priorities:

I. Develop a strategy for dealing with this car;
II. If keeping it, prioritize issues to be diagnosed;
III. After diagnosis, prioritize & plan maintenance/repairs. Let's do I & II FIRST

I. Strategy:

The decision you make about how or if you deal with this car will set a pattern that likely will affect how you deal with such issues for the rest of your life, so choose wisely. That may sound ominous, but I'll give my own example.

I have always had a unique (NEVER brand new) car, but I NEVER could have afforded such a car if I had bought it new, or had to pay someone else to maintain or repair it. I grew up in a small town in the 60's where no local shops knew anything about foreign and sporty cars. In college, I had a Triumph TR4A and then a 427 Corvette. In Law School, I had a Jaguar XKE. ONLY way I could do that was by getting the Service Manuals, learning how their systems worked, and maintaining them myself. My father was an engineer who had done the same thing to maintain distinctive cars during the depression, so I learned a lot from him, had the use of his tools, and even had the use of a "backup" vehicle from him if mine wasn't able to go on a given day (which was very rare).

So I understand your desire to have something unique and sporty, and how that makes you feel. If we are honest, virtually all of us would feel let down if we had to drive something average. However, you have to be honest with yourself and acknowledge that there is a price in time AND money to having something unique. Your 11-year-old 335i IS and will be HIGH MAINTENANCE, but the more you understand & properly care for your car, the LOWER the expensive maintenance will likely be. If you really want to (and can afford to) spend the time and effort to learn how to maintain your own vehicle, there is a wealth of information online that will enable you to do so.

Whether you own a 10-year-old BMW, Honda, Toyota, etc. there WILL be unexpected issues requiring proper diagnosis and repair, and also regular maintenance to reduce the likelihood of "unexpected issues." Some of what happens to your vehicle will be just dumb luck, but the more you know, and the better diagnosis & routine maintenance you give your car, the BETTER your LUCK will be.

I chose to invest in learning how the various systems of my vehicle work, and to rely upon my own knowledge and effort to take care of it. Even if you attain a position as a professional or executive after school, and you want to devote ALL your time to that and pay someone else to turn the wrench, it is rewarding (BOTH financially & intellectually) to be able to understand your vehicle and diagnose/avoid problems using that knowledge. So choosing to go down the DIY road NOW, is NOT an irreversible decision. On the other hand, choosing NOT to, and choosing NOT to learn how your vehicle works and be able to diagnose issues IS something that you will probably NEVER reverse in your life.

If you have some financial cushion from your family, and/or a "spare" vehicle that you can borrow from family or friends if yours won't go, then the main concern is time (we ALL have the same limited number of hours in a day). Can your studies, job, family demands, etc. afford the time you WILL have to spend with your "new hobby"? Once you get past the learning curve with a new-to-you vehicle, many/most of the regular maintenance (oil changes, brakes, hoses, belt, fluid changes, etc.) you will be able to do in not much more time than it would take you to go to a shop for the work.

If you are going to essentially become a "Professional Auto Technician" so that you can understand, diagnose & maintain your own vehicle in a competent manner, you will have to also recognize that, like Continuing Professional Education mandated for physicians, attorneys, etc., you WILL need to keep up with new technology and diagnostics methods and tools, the same as ANY business person does. So there are a LOT of issues to consider. Most people make the decision based upon how the car makes them FEEL as opposed to a completely rational, objective analysis based upon time, money & other dull issues.

Your car/ your time/ your money/ your future/ YOUR DECISION

II. Diagnosis Priorities:

1. OIL LEAK/CONSUMPTION
2. Top Radiator hose & Head to Thermostat (bypass) hose
3. Throttle Gremlin (diagnose that as you deal with the the first two items) -- this will be the most difficult diagnosis, and INPA/ISTA can probably help, NOT by showing codes that your P-code reader did NOT, but rather by showing real-time info on Eccentric Shaft & Accelerator Pedal Module position and sensor output signals. Your current level of issue with erratic throttle is "livable" so I would defer action on that pending dealing with oil & coolant issues. Just be sure and IMMEDIATELY note ANY worsening of throttle symptoms.

I would suggest obtaining the K+DCAN cable, downloading/installing INPA in your free time, and NOT in a panic. If you have a warm/dry place to work, in the next few days, try to diagnose the oil leak as described in Post#5 above. Get a pair of ramps similar to the following ($35) from Harbor Freight or Amazon; these are also great for getting under the car to change the oil/remove the drain plug & place drain pan (on level pavement):
https://www.harborfreight.com/magnum...ock-67722.html

Take some photos & post back and we'll take it a step at a time. Also let us know if any smoke from the Exhaust/Left side of the engine when hot, or gray/blue smoke from the tailpipes, and if any oil film/residue on rear bumper around tailpipes. If you are leaking/burning a quart per 500 miles, you MUST have one of the following:
a) a very wet/slippery parking area;
b) oil coating the underside of the car; and/or
c) oil film on the rear of the vehicle.
Those are ALL clues to look for, so please let us know what you find.

George
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