Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E36 (1991 - 1999)

E36 (1991 - 1999)
The E36 chassis 3-Series BMW was a huge hit among driving enthusiasts from the first moment the car hit the pavement. The E36 won numerous awards over the years it was produced and is still a favorite of many BMW enthusiasts to this day! -- View the E36 Wiki

Reply
 
Thread Tools Display Modes
  #1  
Old 06-07-2013, 11:17 AM
Oldskool67 Oldskool67 is offline
Stubborn DIYr
Location: Southern Ontario Canada
 
Join Date: Mar 2010
Posts: 40
Mein Auto: 2001 330ci
Rough idle+bad mileage - otherwise drives fine (??)

Hi Guys - I usually hang in the E46 section, but I'm hoping someone has some wisdom for my son's '94 325is: This car has been a real gem...up till about a month ago, now at just over 300,000km (~180k miles). The thing WILL NOT stay idling without cranking that small adjustment screw on TB as far as can go...with that, idles very rough at about 700rpm. Hot/cold makes no difference. Almost everything on this engine is original, or very old (except water pump)...so far changed fuel filter (was due anyway), swapped ICV with known good one, soaked entire intake side down with TB cleaner (check for vac leaks - inspected all intake boots including ICV elbow too..no cracks) checked plugs (normal tan colour), cycled a new coil through all 6 cyl, checked DME (doesn't look like got wet), installed new FPR as original was still in there. Compression ~220psi - all 6cyl when hot, cleaned MAF - runs worse when unplugged, checked TPS - tried unplugged. Ran seafoam through the gas to hopefully clean up injectors. Listened to each injector with stethoscope -all sounds as though working properly (electrically anyway ..normal solenoid sounds...otherwise hard to tell I guess)...all has made NO difference whatsoever. NO CODES from computer either, Oxygen sensor (new Bosch unit) was changed about a year/3000mi ago. I do not believe cat is plugged since change was sudden...was running smooth as silk as always, then one day on starting under typical conditions...now crappy.

Starts fine hot or cold, and smooths out/seems to drive normally when above about 2000 rpm. Power feels normal above 2000 rpm.

I plan to give in and buy fuel pressure gauge to see that pump is OK (my current oldschool gauge is no good for fuel injection pressures lol). Was wondering if should try unplugging the CamPS to see what would happen...running out of ideas!

Thanks for any suggestions/wisdom. I've scanned the threads a ton...and haven't found any that give a clear direction for me... If I can't figure out, I guess will have to give in and schedule an appointment (now booking 3 weeks wait!) with the only local indy mechanic I trust and knows BMWs....not cheap for diagnosis I expect.
__________________

2001 330ci ZSP/ZPP 5-Spd Of Course!
Reply With Quote
Advertisement
  #2  
Old 06-07-2013, 02:38 PM
drivinfaster's Avatar
drivinfaster drivinfaster is offline
bimmerfest Supporting Member
Location: in the sticks you piney
 
Join Date: Nov 2007
Posts: 10,923
Mein Auto: rescued bmw's
well, screwing the adjuster is going to throw everything off....that's usually the last thing i would suggest doing first.

now, to get this in some sort of triage....

if you unplug the crank position sensor your engine will simply crank but not let the dme know what is going on. they also usually fail hot, so it's not the first culprit i would check, either.

i'd see what engine vac is @ idle. you may have a leak, so check the vac lines under the manifold.

other culprits that it could be are faulty maf (running in default mode @ higher rpm, possibly?), but if you are doing these 'checks' with the adjuster screw all the way in, you're wasting your time and could quite possibly be getting false results. i'd put it back to where it is supposed to be and recheck the specs.

do you have a dvom??





df
__________________
Reply With Quote
  #3  
Old 06-07-2013, 03:10 PM
Oldskool67 Oldskool67 is offline
Stubborn DIYr
Location: Southern Ontario Canada
 
Join Date: Mar 2010
Posts: 40
Mein Auto: 2001 330ci
Thanks for your reply...
I was going to try to unplug the CAM position sensor.... I knew it wouldn't run at all with the crank sensor unplugged (seems to me it won't even start if it is acting up..).

With the CAM pos sensor unplugged - will the DME go to some default and still run in some limp mode? I read somewhere that a faulty CAM pos sensor, can have rough idle...but I thought would get a code for that?

I HAD to screw the adjuster in... otherwise would stall right away with idle screw at stock position (starts fine every time with little cranking as normal, just will stall right away if you don't press the throttle...with screw turned in, at least will start and settle at about 700 rpm). If I unplug the TPS with the screw turned in to that spot, it still runs at same rpm...I would assume an unplugged TPS would cause DME to default to idle speed (?)...still rough, no change.

I will check again for vacuum leak(s), all hoses seemed intact under manifold...and dousing with TB cleaner produced no change in engine speed or smoothness....Id did check vac with gauge, and was in normal range if I recall...will check again tomorrow (car is gone for the day at moment). At least with the idle screw turned in to where it is, it won't stall and is totally driveable...just idles like crap, and gets lousy mileage (probably not good for cat if running real rich I bet...no visible black smoke out tailpipe though - not even when starting or changing gears).

I have an old-school "A"vom (analogue meter) from the seventies - still works well, but not as easy to read...I guess I should grab a modern digital one since they are relatively inexpensive...
__________________

2001 330ci ZSP/ZPP 5-Spd Of Course!
Reply With Quote
  #4  
Old 06-08-2013, 08:15 AM
evanwray evanwray is offline
Registered User
Location: johannesburg
 
Join Date: May 2013
Posts: 44
Mein Auto: bmw e36 325i
I was having the same problem as you with my 1993 325i. Did everything, tried different combinations, even got trivial and replaced oil dipstick O-rings and the like in an effort to get it to idle properly.
My eventual problem was damage to the ICV wiring. Have you checked that the ICV vibrates when the ignition is switched on?
I agree with the previous post in that your idle screw must not be turned out. Your throttle butterfly must be fully closed for your ICV to work properly.
check the vacuum line to the fuel regulator at the back as well.
Reply With Quote
  #5  
Old 06-11-2013, 11:41 AM
Oldskool67 Oldskool67 is offline
Stubborn DIYr
Location: Southern Ontario Canada
 
Join Date: Mar 2010
Posts: 40
Mein Auto: 2001 330ci
Thanks for your comments, evanwray.

I messed with this a bit more over the weekend...
Putting the idle screw back to where factory setting slows engine down considerably...and tends to stall - especially when driving - will most surely stall if you come to a stop unless you heel-toe the brake/accelerator...a PITA. With car sitting, if you verrryy slowly release the accelerator pedal, it will stay running, but only barely. It stays at steady speed - no surging, just very rough. Changing the ICV valve for a known good (and cleaned) one under this condition caused some odd surging very briefly upon first try, but settled down to very slow rough idle quickly after that, same as with original ICV...every start since has been the same - no surge, just slow rough idle. I will check for "hum" or otherwise vibration from the ICV next to see if it seems to be operating, but I think it is. Since idle is steady speed, I am guessing ICV is OK though...we'll see.

All related wiring appears intact, connectors clean, vacuum hoses are all good as far as I can tell. I replaced the vac hose to the FPR already...and again spraying all down with TB cleaner had no affect. I even tried unplugging the Cam position sensor...made no difference other than making check engine light go on... no codes otherwise.
Stuck my vac gauge on and was getting 13 inches mercury of vacuum...the marking on the (admittedly very old) gauge has notation "late ignition timing" at/near this spot...while under 10 inches vacuum is noted as possible vacuum leak. Not sure if any of the notations from this gauge are valid anymore. I will back the idle screw off to factory setting again, and recheck the vac reading...

Does anyone know what vacuum should be at idle?

I am going to get a newer fuel pressure gauge and see if pressure is too low (though not sure this would cause poor idle....and I think unlikely since power is fine above 2000 rpm) - figured wouldn't hurt anyway..

Drivinfaster: I also wondered about the MAF - its been cleaned (no change)....unplugging it makes it run even worse (that's with the idle screw turned in...when unplug MAF with screw at factory setting and engine barely idling...it simply stalls out)...leading me to believe it is at least operational at idle...but maybe its still sending mixed signals to DME? Wish I had a spare to try...will maybe try to locate reasonable a used one.

Based on other threads I've read here, I am starting to suspect that maybe the DME itself is acting up (it is the original as far as I can tell? - when I opened the compartment to see if it was dry, it seemed as though it had never been opened before - or at least if it was, a very long time ago)...wish I knew someone that had same year/same engine that I could try theirs...but in my area, 325 E36s are few. Might have to just simply buy a used one and give it a try...I know a parts guy that might have one or 2...maybe he'll let me try one...

again any further suggestions are appreciated..the saga continues
__________________

2001 330ci ZSP/ZPP 5-Spd Of Course!
Reply With Quote
  #6  
Old 06-11-2013, 05:28 PM
Nicky3 Nicky3 is offline
Officially Welcomed to the 'Fest
Location: Nashville,TN
 
Join Date: Dec 2012
Posts: 619
Mein Auto: 96 328is
13mm of vacuum is low for a healthy engine. Should be between 16-20 mm/hg on a modern engine. Not sure what is specific for BMW but I know 13 is low for sure. The fact that it smooth's out at 2k RPM, leads me to believe you have some sort of vacuum leak. It's a birds nest under the manifold. Check again. Did you check the intake manifold gasket? Spray around it with carb cleaner or propane.
Reply With Quote
  #7  
Old 06-11-2013, 07:32 PM
Oldskool67 Oldskool67 is offline
Stubborn DIYr
Location: Southern Ontario Canada
 
Join Date: Mar 2010
Posts: 40
Mein Auto: 2001 330ci
I suppose it is hard to verify that all those hoses are ABSOLUTLY intact since most are under the manifold. Maybe I'll pull the intake and replace those gaskets since not expensive, and go ahead to replace all the vac hoses...can't cost that much...I am sure they're all quite old anyway....I'll see what happens and report back..

Thanks
__________________

2001 330ci ZSP/ZPP 5-Spd Of Course!
Reply With Quote
  #8  
Old 07-29-2013, 09:08 PM
chrisnash11 chrisnash11 is offline
Registered User
Location: Souhern Ontario
 
Join Date: Apr 2011
Posts: 5
Mein Auto: 2004 330ci zhp
So this car is now my problem as I have purchased it from my younger brother. It happens to be my first car too. Anyways, since I bought it, I have tried a different computer, and pulled the intake manifold, replaced intake gaskets, throttle body gasket, replaced vacuum lines and when I started it, it ran the exact same. One thing that I find to be odd is that I can start the car with the throttle position sensor disconnected and it runs the exact same as when it was plugged in. I am at a loss here. We will be testing fuel pressure, but since it runs fine above 1500RPM I highly doubt that that is the issue. I am wondering if it could be a vanos issue?
Reply With Quote
  #9  
Old 07-30-2013, 02:46 AM
evanwray evanwray is offline
Registered User
Location: johannesburg
 
Join Date: May 2013
Posts: 44
Mein Auto: bmw e36 325i
A typical symptom of a faulty vanos is loss of power/torque,surging around 3000rpm, difficult take off from stationary, increased fuel consumption and general lackluster running.
The servicing of the vanos unit is quite a labour intensive job requiring special tools and expensive seals. Make sure of the symtoms before you commit yourself to the aggrevation of servicing the unit.
It looks like you have covered most of the regular issues that cause the bad idling.
The throttle sensor should make a difference when you unplug it, a small change but a change none the less.
Have the plugs been changed recently? coils clean and earth straps clean and tight?
Has battery been disconnected? If not, disconnect, leave 30 mins and reconnect. This will reset the system.
Reply With Quote
  #10  
Old 07-30-2013, 06:08 AM
chrisnash11 chrisnash11 is offline
Registered User
Location: Souhern Ontario
 
Join Date: Apr 2011
Posts: 5
Mein Auto: 2004 330ci zhp
I will definately try the battery thing when I get home from work tonight. Vanos rebuilds do not scare me, but it doesn't sound like that is my issue. I do have a set of beisan systems seals to put in but I am going to focus on the idling issue first. I will try cleaning the throttle position sensor as well. If you unplug it while it is running it makes a difference, but if u unplug it and then start up, you can't tell the difference.
Reply With Quote
  #11  
Old 07-30-2013, 06:27 AM
Josh1991 Josh1991 is offline
Registered User
Location: Exeter, England
 
Join Date: Jul 2013
Posts: 3
Mein Auto: 316i
Rough idle+bad mileage - otherwise drives fine (??)

I've been having a similar problem that I just posted for the past month or so except its not so bad ill be keeping an eye on your post to see if you manage to sort it, good luck!


Sent from BimmerApp mobile app
Reply With Quote
  #12  
Old 09-22-2013, 09:29 PM
chrisnash11 chrisnash11 is offline
Registered User
Location: Souhern Ontario
 
Join Date: Apr 2011
Posts: 5
Mein Auto: 2004 330ci zhp
So just an update. I never was able to figure out the problem with this car. I have decided to go another route with the car...lsx motor and full restoration. I will be starting a new thread when I get started with things. It may take a little while to get started with this. On another note, I have purchased a parts car. It is a 1998 328is. The motor and trans have 285000 on it and a new clutch. It is for sale if anyone is looking.
Reply With Quote
Reply

Bookmarks


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E36 (1991 - 1999)
Today's Posts Search
Thread Tools
Display Modes

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



Forum Jump


All times are GMT -7. The time now is 04:23 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms