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Discussion Starter · #61 ·
I've seen other cases where the O2 pilot mod has caused rich fuel trims.

Is the root cause of your oil consumption problem carboned up oil control rings on the pistons or a faulty CCV?

How would adding extra vacuum to the CCV stop oil bypassing the carboned up oil control rings? There have been a couple of recent threads on soaking the pistons or running cleaner through the fuel to clean the carbon deposits off the pistons etc. Do some research.

If the CCV oil return tube is blocked, or the dipstick tube section of the oil return is blocked, the returning oil would have nowhere to go, so it's off up the CCV system to the inlet manifold. How would the O2 pilot mod fix this. @Sapote and @The_Fixer what is your experience with the O2 piolet mod?
So this could be the rich trim issue separate from the sold start issue - unless it is causing a vacuum leak ? due to more vacuum than is expected is that possible?

Is it possible that there is a vacuum leak and is being covered up (in the data logs by the rich running) and that is the (potential) cause of my cold start issue ?

I will look into the issue CCC is on my list to do but since this problem came along I started looking into this - I know the o2 mod is a "band aid" fix

lets se what the others have to say regarding the o2 mod
 

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2000 E46 323i, 3.0L, 2.8L and 2.0L Z3's
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You could be correct with all questions.

Unplug the hose coming off the bottom of the CCV regulator. Blow though it. You should be able to hear air bubbling though the sump/oil pan oil. If you can't blow though it, then you have found one of your problems.
 

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Discussion Starter · #63 ·
Removed o2 mod - its been a couple of days now and fuel trim are still -8 - im going to conclude this was not the rich problem, I did reset adaptations.

I will get a smoke test done at work to rule out a vacuum leak causing the cold start issue and proceed with the Maf replacement afterwards.

I will keep you updated,

in regards to checking the DME does anyone have a diagram on which spots to check ?
 

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Discussion Starter · #64 ·
Got a smoke test done at work, no leaks - only thing I didn't check was the Brake booster - i was a little unsure on just unplugging the hose before driving 20 miles home again

Maf replace is next on the list
 

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Discussion Starter · #65 ·
I ordered a new Maf - went and picked it up - didn't look new had dust on it so i was dubious already( it was inside a box in bubble wrap) - fitted the maf and started the car - immediately the idle was hunting badly - thought I would try it down the road as the LTFT were - 7/-8 ish and short term were + 25 or something silly - maybe its sorting itself out - I was wrong

drove about 1 mile up the road lost all power, pulled in and checked maf was reporting 192g per second - legit sounded like a rotary engine - unplugged the "new" Maf car back to 6 cylinders - plug the New maf back in and it started gasping for air again - sounded like I was firing on 1 cylinder

took the maf back to the shop and got a refund

I though it would be a good idea to unplug the maf and try a cold start to see if my misfire went away

it didn't go away however was significantly better - normally it takes about 5/10 mins for the misfire to go away unplugged it was about 2 mins

I do plan on doing the 3 logs with maf unplugged for NZ00Z3 - will upload later
 

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Discussion Starter · #66 ·
new Simens/Vdo Maf arrived today - I have done a cold start today and car went to fuel status 8 after about 10 seconds - once warm the fuel trims are back to -7% on both banks at a 60 mph cruse however wasn't ideal as was in rush hour traffic so not a steady constant load

how quickly should you be seeing results after installing - I think I have done about 50 miles since installing earlier
 

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2000 E46 323i, 3.0L, 2.8L and 2.0L Z3's
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50 miles is plenty for the fuel trims to adjust to the new MAF.

Fuel System Status 8 is generally all about Pre-Cat O2 sensor faults.
 

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Discussion Starter · #68 · (Edited)
Well they were new as of a month or 2 ago when I replaced them. States open loop due to system failure. Could it be that these new sensors are faulty ?
I have a short cold & warm log just need a 60 cruse to upload
 

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Discussion Starter · #73 ·
Hi all might have had a brake through,

after reading through a post on the brake booster leaking I thought I would dis connect and block off and check the trims.

below are the results - warm idle brake booster blocked off .csv

can someone tell me how to check if the issue is at check valve or the booster itself ?
I disconnected where the soft hose meets the plastic hose that goes across the engine bay - so after the check valve for this test
am I right in thinking the issue is the booster itself
?
 

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Discussion Starter · #75 ·
Thanks NZ00Z3, I have left the booster disconnected and blocked off the hose so I can try in the morning cold
I will keep you updated
I did however hear a hissing when I shut the car off from the booster area so this might be it finally!!!!!!!!

thanks for your help
 

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Discussion Starter · #76 · (Edited)
I tried it this morning with the booster vac line blocked off - still had a misfire however the car went into status 8 almost immediately.

is there a way to reset the Fuel trims before I do this test as I'm convinced the car is going into status 8 due to the fuel trims being -8% before starting and as nz said before the sensors are trending super lean and it thinks they are lying - maybe, I don't know still working out how the computer uses all the data it is given
 

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Thank you for the logs.

It's been a head scratcher of a morning working through the logs. Ended up doing a detailed read of the 4 pages of this thread to see if I have missed anything. I think I did, the P0444 Evap purge valve code.

The P0444 code relates to the DME detecting an incorrect voltage drop across the purge valve. For some reason it is very particular, so make sure all the connections are tight and clean, you need an OE or genuine BMW purge valve, etc. Now lets say that the valve is failed open and the DME can't get the electrical readings it wants:
  • P0444 pops up.
  • The manifold vacuum is applied to the Evap system constantly.
    • Could this look like a vacuum leak at cold start?
    • Could this be a source of enough extra fuel vapor to cause rich fuel trims?
  • Would/shouldn't the leak detection system see the faulty purge valve as a leak?
I don't know, but we are looking for something out of the ordinary. If you are still getting the P0444 code, replace it with a OE or BMW purge valve. Reading old forum threads indicate that aftermarket ones, while they work, they do not provide the DME with the electrical characteristic that are needed to stop the P0444 code.

To ensure that the engine runs correctly when it is cold and/or idling, the DME does not open the purge valve until the engine has warmed up and is under load. The purge valve is then modulated on and off, to allow the stored vapor in the charcoal canister to pass into the inlet tract.


Cold Start
  • RPM, MAF, Load chart looks good.
  • Pre-Cat O2's show bank 1 trying to heat correctly, then start to switch in closed loop (status 2), but not full range, then flat lines just above 0.0V during status 8 (Pre-cat O2 fault). Bank 2 goes rich during heating, really struggles in closed loop (status 2, )then flat lines just above 0.05V during status 8 (Pre-cat O2 fault).
  • These are relatively new Pre-Cat O2's, so should be telling the truth. Very weird results.
  • The fuel trims follow the pre-cat O2's leads during the closed loop section. Bank 1 head high lean while bank 2 heads high rich.
  • Bank 1 Post-Cat O2 confirms the really lean mixture by dropping to nearly 0V. Bank 2 post-Cat O2 sensor has a problem. The heater is not working or the sensor is faulty. It moves a little in the logs, but not by much.


Product Rectangle Azure Plot Slope

Rectangle Slope Plot Font Parallel


Cruise
  • RPM, MAF, Load and Pre-cat O2 charts are acceptable.
  • Fuel trims, shows the mixture is running rich and outside the normal band for E5 fuel.
  • Post-Cat O2's shows that the bank 1 cat is not a spring chicken, but is still working well enough to avoid the P0420 codes. Bank 2 is an unknown quantity due to the O2 sensor giving bad data.


Rectangle Slope Font Parallel Plot

Rectangle Slope Plot Font Parallel


Hot Idle
  • From the charts, only the fuel trims is out of the acceptable bands. Not as badly out as the cruise trims.

Rectangle Plot Slope Line Font


Time Invested
It's taken me 4 1/2 hours today to work through your logs, read the thread, think about this problem and write up this post. Hope the purge valve fixes it?
 

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Discussion Starter · #78 ·
Hi NZ, I bet you are as frustrated as me with this car haha,
all recent logs are on e10 - couldn't remember if the acceptable range was closer to lean or rich for e10 vs e5

I have not had the purge valve code for some time must be at least a month or two, I have had that code on and off since owning the car for over a year now. so did rule it out initially
im at a loss now of what to do next

im confused why when i blocked of the brake booster and started it cold it still misfire even though it brought the trims closer to spec
 

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Hi

Yes, I'm frustrated with the car. Wish I was just around the corner so I could drop over and test it to death myself. But I'm deep in the South Pacific and you are on the other side of the world in the UK.

The E10 limits for normal operation are:
  • Upper Limit = 8.5%
  • Lower Limit = 0.5%
So, you engine is running very rich.


This shouldn't be that hard?

Rich conditions are caused by:
  • Too much fuel- Fuel pressure tested and it's good. Problem is on both banks, so should not be an injector problem.
  • Not enough Air- New VDO MAF fitted. Testing shows it runs a little under reporting. This would cause lean problems, which you don't have
  • A faulty sensor fooling the DME into thinking one of the above 2 are happening- Both the MAF and Pre-cat O2's are new.
  • Blocked Cat's.- Bank 1 looks OK, Bank 2 is an unknown quantity as there are no valid signals to tell it's condition.
  • DME tune- ??

The DME tune is one area we have not discussed.
  • Is the DME still on it's standard BMW tune?
  • Are the 2.5L injectors fitted? Are the injectors the purple body 3.0L injectors? The cruise log fuel trims look remarkably like logs of a 2.5L engine with 3.0L injectors fitted and the DME injector table still being for the 2.5L injectors.

The main control loop is:
  • MAF measures the air going in
  • DME injects fuel to match the air mass
  • Pre-Cat O2's measure combustion
  • DME adjusts fuel trims

Suggestions
  1. Unplug the DME and inspect the connectors for oil or coolant contamination. Especially connector X60003. Its the really big one, number 3 counting forward from the fire wall. There have been cases of oil contaminating that connector and causing rich conditions.
  2. Time to break the main control loop and see what is happening. This will look closely at the pre-cat O2's. Unplug the MAF. With it unplugged, run the 3 standard logs.
 

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Discussion Starter · #80 ·
I am glad you are helping me, wouldn't have gotten this far otherwise.

when I took the injectors out there were completely black plastic bodied, I have removed the connections from the DME and cleaned with electrical contact cleaner - it was bone dry
I know you mentioned previously about oil contamination causing rich conditions.

I will try to run the logs tomorrow with MAF disconnected - car was purchased on 140,000 miles so who knows if anyone has been in the DME and mapped or done something
I do wonder as I must have done 10,000 miles in the car trouble free in the first 6 months - if it was the DME why it would start now
 
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