How does the 'code' feature work?

[tim eh?]

I mean, I know how to use it but how does it disable the car? Does it cut fuel, or something else?

[ss2115]

I mean, I know how to use it but how does it disable the car? Does it cut fuel, or something else?

If your refering to the code setting on the OBC, then I'm pretty sure its just telling the cars ECU not to start the fuel pump on turning the key to ignition, nor the fuel injectors from firing nor the ignition system from firing sparks.
ie: just a complete non-obeyance of the engine to start and operate anything past the "ignition On" position of the key.

[repenttokyo]

Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

[ss2115]

Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

Huh ?

[Rick L]

+1 What he say...?


Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

[Rick L]

I thought it disables the starter.

[Ferret]

The OBC is an extension of the engine's ECU - it's a dumb terminal into the heart of it.

This means when you set the code, the ecu will just make no effort to run the engine, the program will not start. It's like someone flipped off the power switch to the actual engine running bits of the ECU.

[repenttokyo]

wow, no one has ever seen ghostbusters?

[tim eh?]

wow, no one has ever seen ghostbusters?

aaaaaah I was trying to figure out what I knew that from....

so THAT'S how it works

the reason I am asking is ... if it cuts fuel I may have a fuel delivery problem, if it cuts spark I may have a spark problem - just fishing for clues on a rare starting problem. I tried to start the car without first disabling the code feature the other day :D and then the problem presented itself.


I thought it disables the starter.
nope starter cranks :)

[ss2115]

It disables everything with running the motor - not just fuel, not just electrics - everything.
It simply tells the ECU not to have anything to do with the engine.

Therefore, your problem could still be anything. It may only be coincidence that it occured after trying to start the engine without the release code.

But if it was to have been a catalyst, I'd start with spark plugs - they may have wetted and burnt off the electrode, or got some junk carbon specks between the electrode or around the centre tip and shorting the spark to the side.

[tim eh?]

It disables everything with running the motor - not just fuel, not just electrics - everything.
It simply tells the ECU not to have anything to do with the engine.

Therefore, your problem could still be anything. It may only be coincidence that it occured after trying to start the engine without the release code.

But if it was to have been a catalyst, I'd start with spark plugs - they may have wetted and burnt off the electrode, or got some junk carbon specks between the electrode or around the centre tip and shorting the spark to the side.

Thanks - I agree it could be coincidence, I am grasping at any straw that occurs as I have chased this for a long time. I'm not really desperate to fix it but every now and again I try to rule something out and do some basic 20 year old car maintenance at the same time.

Since I (foolishly) bought the car in 2007 I've done the following basic stuff (off the top of my head) that I thought might be related

cap
rotor (twice)
wires
coil
cps
plugs (http://www.bimmernut.com/forum/attachment.php?attachmentid=6681&d=1239315806) (4x - they never look bad really but they get old a little fast I think)
fuel pump
fuel filter
fuel lines
regulator
main relay

I could write a @#^%^$ essay about all the symptoms, but I think most people on the board are a little sick of it (a long time ago) ... currently looking at the injectors, afm, any kind of temp sensor that feeds info to DME (it happens only at a very specific temperature), engine wiring harness(es)... I'm a little sick of it too. I think it is related to an impossible to find voltage drain somewhere in the engine electrical system but that could be a seperate deal... I sure would like to know how many amps the engine electrical system alone is supposed to draw at idle, mine pulls 30 amps just the wire to the e-box.

AH welll like I said I'm pretty sick of it and don't get to do much in winter besides bail water anyway... I know exaclty when (tempwise) I will stall out so I can just make sure I'm not in a bad spot for it, I once had to push it across 6 lanes of traffic but i play it safe now :D.

[ss2115]

Thanks - I agree it could be coincidence, I am grasping at any straw that occurs as I have chased this for a long time. I'm not really desperate to fix it but every now and again I try to rule something out and do some basic 20 year old car maintenance at the same time.

Since I (foolishly) bought the car in 2007 I've done the following basic stuff (off the top of my head) that I thought might be related

cap
rotor (twice)
wires
coil
cps
plugs (http://www.bimmernut.com/forum/attachment.php?attachmentid=6681&d=1239315806) (4x - they never look bad really but they get old a little fast I think)
fuel pump
fuel filter
fuel lines
regulator
main relay

I could write a @#^%^$ essay about all the symptoms, but I think most people on the board are a little sick of it (a long time ago) ... currently looking at the injectors, afm, any kind of temp sensor that feeds info to DME (it happens only at a very specific temperature), engine wiring harness(es)... I'm a little sick of it too. I think it is related to an impossible to find voltage drain somewhere in the engine electrical system but that could be a seperate deal... I sure would like to know how many amps the engine electrical system alone is supposed to draw at idle, mine pulls 30 amps just the wire to the e-box.

AH welll like I said I'm pretty sick of it and don't get to do much in winter besides bail water anyway... I know exaclty when (tempwise) I will stall out so I can just make sure I'm not in a bad spot for it, I once had to push it across 6 lanes of traffic but i play it safe now :D.

I did a quick search looking for posts on your problem, but probably didn't go back far enough to find them.
Seems like you've gone through quite a bit of stuff in trying to find the problem.

Is this temperature related problem engine temperature or ambient (weather) temperature sensitive?
When it happens, does the engine misbehave at speed and then cut out, or are you saying that you come to a stop and then the engine just cuts out?

If the engine misbehaves while you are driving and you can feel or recognise symptoms that its going be be a bad day, then I would consider going to a tuning shop with a dyno and exhaust gas tester and try to recreate the problem. You can vary the engine temp to some degree with the fan at the front of the engine and if you can make the problem occur, you might be able to actually see whats happening - eg: suddenly goes rich, suddenly goes lean, spark stops, timing moves out of spec etc.
It might be worth paying an hour or two's dyno time if this problem plagues you to the point of insantity (it would me because I could never depend on the car).

If it just stalls and won't restart when you come to a stop, the dyno might still help but it could be a lot harder to recreate the problem.

You've gone through a heap of stuff.
There's a couple of things might be worth trying -
- Disconnect the Ecu for a few hours (overnight) so that it forgets all its fuel trim information and goes back to an as new factory setting.
- I would check every chassis to engine and chassis to transmission earth leads very carefully - possibly even take them off, clean then and reinstall them. If the cable looks under-rated or in poor condition, replace it. BMW earth leads are all a lightish brown colour or tan colour.
- Check that the fuel pump has a really good solid earth connection.
- Borrow or buy a new Battery. It may have a faulty cell or a poor internal post contact. Doesn't matter that the engine turns over: it could be that its a high resistance fault and there's nothing left for the engine to run. The ECU will not fire the ignition system once the battery voltage drops below a certain threshold and the BMW's are particularly sensitive to this. The battery might be getting to a certain underbonnet temperature for the fault to occur.
- That last point brings up another - check that the battery is being charged correctly. If its perpetually in a low state, you might be floating around the ECU threshold all the time. (Does the problem happen more often at night when the lights are on or in the rain when the wipers are operating?)
- Shogun has often posted about certain modules that eventually get dry soldered joints. It might be worthwhile searching for his posts and looking for any module that could be engine related and applying his suggested fixes. He has certainly delved deeply into the electronics side of the BMW's.
- Last point is fairly obvious but have you connected a scanner and looked at any stored fault codes. They might give a clue at least in the area to look if not the actual fault itself.

I cannot for now think of anything else, but it would be good to hear if any of these checks work for you.
best regards,

[tim eh?]

Hey man thanks for taking the time! I have done most of that already tho...

The problem is engine temperature related- it happens during warmup when temp gauge just out of the blue so it is actually difficult to recreate once the engine is warm. If I leave home and go a certain way I will stall at the same 4-way stop about 2 minutes away almost every time, no matter the ambient temperature. I will stall and not be able to restart for about a minute, then she starts up like nothing happened.

The stall will happen after I stop and try to accelerate again from zero, no matter if I am gentle or if I floor it. The power loss feels much like my old van with bad points used to feel. It happens with nothing on (ie lights,radio,blower,etc) and with everything on, I don't think it is a power supply problem. Although, when I start the engine (cold) I can get 14.2+V until I shift into gear, and then it drops to around 13.7 even if I shift back to park.

I constantly monitor my voltage using the obc. It is lower than it should be but always reading a healthy 13.5+ volts or I start shutting down accessories (picture apollo13:D). I have also tested with a DMM which corresponds enough with the obc that I feel comfortable using it as a reliable meter. There is never a drop in voltage that corresponds with the engine struggling, which happens for only a minute or so and I don't stall unless I come to a stop first. I have checked and doublechecked the charging system, installed a new bosch alternator (a few alternators actually), run a new alternator charge wire, new battery, tried a friend's battery, run a seperate B+ to the starter, replaced the battery terminals, fusible links, ground cables (engine->ground->batt-). None of any of this has made the slightest noticeable difference. I have done a couple of shogun resets not to mention just leaving the battery unhooked... tightened belts, loosened belts... unplugged the icv, that kind of thing

I did get my mechanic to run a scanner on it and it came up with one vague fault code related to the a/c. This would make sense as I have completely disconnected the a/c, including even the aux fan. The electrical connector for the fuel pump looks ok but I haven't put a DMM on it, if there is a problem with the fuel pump wiring I don't think it is the plug at least... but maybe I should go and test that with a DMM, I will check for a proper ground there at least. Kind of sucks out here weatherwise right now to be doing that kind of thing.

There is a transmission to ground cable??? I have checked as much of the wiring as I can find and all of it looks like it is in A1 great shape. I have visually inspected a few of the modules and the ones I have looked at all look brand new... I have pored over shogun's posts and his website and many many wiring diagrams. (I'm no mechanic but I have a decent understanding of basic electronics)

The car had a great charging system when I bought it, never dropped below 14V even with everything on and now I have to be careful using the defroster! I didn't notice right away but problems started after the water pump failed in the middle of winter and I blew the headgasket and I took the car to the wrong shop. I wish I knew what they did to it, they went out of business less than 6 months after they opened. Since then I have pretty much done this stuff one step at a time and it has not made any difference, although I have ruled a lot out at least and done some much-needed maintenance. At least I haven't done anything that has made it worse... I think!

I didn't use to stall outright until more recently but the engine has always struggled at exactly the same temp. I haven't really mentioned it because it used to be a very minor issue compared with my electrical concerns, but stalling sucks, I would prefer not to. The first time it stalled was in a really bad place and I had to get out and push the ****ing thing out of the way of a lot of traffic... since then I just make sure I am running at a good temp before I try any left turns at intersections and I've had no problems, I just have to plan for it.

So I believe there is something in the engine that needs 12v that is bunged up and maybe not working as well as it needs to and the ecu is having trouble figuring it out as the engine warms up. That is why I measured the amp draw going to the e-box, but I have nothing to compare it with.

One recent clue... I have noticed once in a while the rpm guage does kind of a self-test on shutdown... to around 12noon it varies a little. It's kind of weird. I replaced the cps already - it was a cheapo but there was no difference. I have to check the other end of that where it plugs into the wiring harness beside the motor, but everything looked pretty good there - see "starter cable" below.

I have a set of injectors going in in the spring, and while I am there I can check some of the wiring for that. The original injectors look like dog barf on the outside. I can never smell gas around there tho when I stall. Also I want to check the throttle assembly a little better and there are some sensors on it that I think I have to check, as well as the AFM. Dyno sounds like a great idea I know someone who does that, although he is more of a mopar kind of guy. Otherwise, well this car has driven me nuts already and for a nutcase it is reliable enough to the extent that I know exactly when it is going to stall, otherwise it runs great and I love driving it (I do carry a fire extinguisher).

some links if you just can't get enough of this...

dead battery/security system (http://www.bimmernut.com/forum/showthread.php?t=35817) I have doublechecked this, everything is disconnected now.

worst mistake I ever made (http://www.bimmernut.com/forum/showthread.php?p=286252) was taking my car to this shop. I think I would have been completely screwed if it wasn't for this forum.

IHKR meltown (http://www.bimmernut.com/forum/showthread.php?t=38910)

charging trouble... (http://www.bimmernut.com/forum/showthread.php?t=39830) it wasn't the battery or the alternator. The reason the battery voltage was dropping overnight was because it gets frigging cold up here overnight.

more charging trouble (http://www.bimmernut.com/forum/showthread.php?p=313362)

more (http://www.bimmernut.com/forum/showthread.php?t=39895)

fusible links (http://www.bimmernut.com/forum/showthread.php?t=39960)

starter cable (http://www.bimmernut.com/forum/showthread.php?t=41368)

blower motor (http://www.bimmernut.com/forum/showthread.php?t=41767)

transmission switch (http://www.bimmernut.com/forum/showthread.php?t=41891)

Let me know if you want more! I have accepted that I may never succeed but must still refer to the car as "my master" and sacrifice live animals to it every second weekend. I am good at fixing my friend's Toyota, my neighbour's Dodge, and my Mom's Suzuki so at least I am getting somewhere. If you made it to the end, thanks, even if you didn't click the links.:)

[ss2115]

Wow.

Well, you've eliminated the stuff I posted well and truly.
Being on a warm-up issue, you could probably still use the dyno and leave the car on the dyno overnight and meet them there next morning and start the cold engine together - ie: simulate the way you drive and wait for it to happen.

But on warm-up and temperature related brings two things to mind for me straight away -
1) the O2 sensor has its own heater to warm it up "artificially" until the exhaust gas gets to the right temperature for the heater not to be required any more. Perhaps the heater is turning off a bit too soon and the ECU stumbles with the changeover information it receives, or perhaps the other way around - ie: the heater is not coming on at all and the ECU is starting the engine under a rich condition ignoring the O2 sensor but then when the sensor comes up to heat it sends conflicting information to the ECU and the engine stumbles.
They can be tested, but perhaps just replace it as they are not overly expensive. But check that its receiving the 12 volts to its heater wires would be a good idea also even if fitting a new one.
Check the plug carefully because maybe when they did the head gasket they got oil in the plug or something and its getting a bad connection. The plug is below the manifold in the engine bay.

2) The throttle body and MAF would be very obvious items to check out very carefully because there is an air temperature sensor and its essential to the ECU to adjust the fuel/air ratio. Have it tested or replace it with a borrowed or new one.

To be so specific as you describe, it would seem to be more inclined to be electrically orientated and likely a sensor or some input to the engine thats causing the ECU to make a sudden change instead of a slow adjustment. It doesn't rule out a fuel problem, but it seems less likely.

Another obvious comment, but have you carefully checked all hoses related to vacuum - not just the brake booster but any little feeder hose at all that might let a shot of cold air in to bypass the MAF?

[tim eh?]

...they {O2 sensors} can be tested, but perhaps just replace it as they are not overly expensive. I replaced the oxygen sensor once. I had a 1221 code that went away when I did so, but other than that I haven't actually tested it. Maybe not expensive for you... $175 US for me last time I checked. But yeah I must test it, especially the heater wires - thanks!

The whole air supply system needs to be checked, all I have done to that is change the air filter and the throttle assembly heater bit that was leaking at the gasket and missing a screw. (facepalm) Plus I cleaned the afm and icv but not the throttle intake itself (I had a look - doesn't look bad), and coolant probably spilled all over the sensors and plugs underneath the throttle assembly. As far as Bentley tests go I have to test afm, icv, air temp sensor, and throttle position sensor in that area around there, plus I have to dig back into the wiring harness and check the cps to dme plug somehow.

I have checked all the pipes for cracks and made sure all the clamps are tight... I replaced a couple of hoses that were old but still ok, I am pretty sure there are no vacuum leaks in the rubber pipes and stuff, but maybe there could be a leak in the gasket between the throttle and the intake manifold or some gasket like that I haven't gone that deep yet.

Injectors are a fun theory for a few reasons...
-my fuel tank rotted out and there was real ugly stuff inside it
-po probably used cheap gas all the time
-they look really bad on the outside
-if they are sticking like mad or the coils are finished they could draw more current than a clean set (i think... maybe ... or maybe the wiring is messed up somewhere)
-the bad shop I went to messed with them
-everything else in the fuel supply system is newish
-I have a set to try and I want to

Very much appreciate the suggestions! I'm not sure if I have one or more problems but one day I will get there. Spring is around the corner and I'll be able to get to it soon...

In the meantime, if anyone with a 6cyl wants to rig up an ammeter to their e-box battery feed I'd be thrilled to know your results.... you can have my cheap pos ammeter if you want. Looking for 30A at idle.