diagnostic help needed: LONG

car is 1999 bmw 528i automatic. 173xxx

the story (condensed version) so far. 

i received the car with a persistent CEL. PO replaced CCV, MAF to TB rubber boots, all 4 02 sensors with Bosch (new), and a few vacuum lines. 

day after purchase, car began misfiring. i replaced all 6 plugs, and added techron to the tank to eliminate bad gas. i then purchased BMW specific scanner, as torque and bluetooth dongle was less than confidence inspiring. car and CEL behavior at that time (approximately 300 miles ago) was that CEL would come on almost instantly upon moving, with misfires upon restart. codes were as follows:

20180802_181908 by Michael Crawford, on Flickr

i swapped the upstream oxygen sensors connectors to see if that changed behavior. 4 mile test drive, with some Italian tune up gave me this:

20180802_190109 by Michael Crawford, on Flickr

for whatever reason, i interpreted this as either electrical or vacuum leak, but im not certain why now. regardless, i checked every single fuse in the entire car with a multimeter. none bad. i cleaned every connector in the oxygen sensor circuit, DME connector, and engine bay with QD contact cleaner. i also replaced every o-ring, gasket, vacuum hose/line, vacuum cap in the entire engine bay. DISA was checked manually, and per research, tested good. visual inspection of the intake tract PO replaced revealed nothing. cleaned ICV and TB. Replaced injector orings. replaced all missing hardware, and hose clamped every hose in the entire place. upon test drive of 200 miles, it seems down on power lower in rpm range, but much stronger higher in the RPM range. no misfires, but on board computer shows significantly worse gas mileage. no misfires anywhere that i can detect. no idle issues. CEL comes on the first time you git about 10mph. following codes after 200 miles.

20180818_171357 by Michael Crawford, on Flickr

im completely at a loss at this point. im begging for help. im in over my head, i do believe. 

but this forum is full of the most experienced, and smartest people imaginable. so between all of us, we should be able to figure this out. i cant afford to shotgun parts at it and still come to spectate at the challenge, nor do i really WANT to throw parts at it until it goes away. i want to fix whats broke, and bring it to a proper state of tune. Hell, if theres one of us local thats really good with BMW stuff, and willing to help, ill buy the food!

but, help me GRM-kanobi, y'all are my only hope 

where do i start?

Well, certainly seems there is something amiss in the o2 circuits.

A couple checks I would try:

1. O2 heater circuits have fuses? Check/replace.

2. See if you can find what pins at the ecu the o2 sensors represent. Measure the resistance of each o2 sensor and heater itself, and check that each wire isn't shorted to ground. But since you are measuring the entire circuit you should see any opens or shorts, which is much better than checking the sensor at it's connector only.

3. Talk to someone who has access to bmw troubleshooting procedures for those codes. (Actually do this one first!)

The heater circuits do have fuses. Which are good.

Ive tried to find pinouts and diagrams to check continuity, however i seem to be incapable of reading them. Or finding ones that make sense. 

Im hoping this thread finds that guy....

I know this forum is full of knowledgeable people, but I think you need to head over to bimmerforums, create an account and copy this entire post there.

Have you...

I have a 1994 325is that has and continues to test my sanity.  Having survived the "every two year" California emissions test I would start with a compression test and then a "real" leak down.  My car has a junk yard replacement and with two marginal cylinders, both less than 150, I am now sure these are the root of my cars issues.  But doing these test will confirm if you have oil fowling the plugs.  The valve cover gasket is a known source of vacuum leaks. The valve cover could be warped, lots of them are.  Then you can replace the coils with their little rubber boots that if not recently replaced are probably bad.  I did go with the e-bay coil set, one of six was bad and replaced without issue by the vendor.

Then you can replace the plugs with the OEM types.  Save the time and money on this, I have learned my lesson.

After the above, find some one who can do the old school smoke test on your car.  This is one the thing that will save you, your hair and keep you from the cigars.

David 

Slippery said:

I know this forum is full of knowledgeable people, but I think you need to head over to bimmerforums, create an account and copy this entire post there.

 

Yes, do this, and post in the General Mechanical Help subforum. There are some very skilled pro techs there.

That said, I would be curious to see the results of an exhaust backpressure test. I wonder if clogged cats are causing issues. Also, have you put a voltmeter on the O2 leads and gotten any raw data from them? Can your computer setup pull live data from the O2s?

Not always an easy solution, but have you tried another ECM?  I don't think 99 had to be reflashed for a different car, but someone else will know better than I.

BMWs up until about that time had ECMs that the plating would start to flake off the pins of the connector causing continuity issues.  I took one out of a 94 5-series once and it was like metallic confetti coming out of that socket.

What do O2 sensors do if injectors are sticking open?

02Pilot said:

Slippery said:

I know this forum is full of knowledgeable people, but I think you need to head over to bimmerforums, create an account and copy this entire post there.

 

Yes, do this, and post in the General Mechanical Help subforum. There are some very skilled pro techs there.

That said, I would be curious to see the results of an exhaust backpressure test. I wonder if clogged cats are causing issues. Also, have you put a voltmeter on the O2 leads and gotten any raw data from them? Can your computer setup pull live data from the O2s?

 

just did. 

have not attempted a multimeter test while car is running to determine voltages. the bmw scanner wont do live data, and for whatever reason, torque is spotty with my buletooth dongle and this car.

mazdeuce - Seth said:

What do O2 sensors do if injectors are sticking open?

Read lean by the time it's so rich it's misfiring, right? Fuel doesn't burn, there's a bunch of O2 that didn't react with anything.

Also wondering whether it's a red herring that it's codes at 10mph, or whether that could say something about a point in the ECU's tests. I suspect that the BMW-specific forum advice is a sound one.

02Pilot said:

Slippery said:

I know this forum is full of knowledgeable people, but I think you need to head over to bimmerforums, create an account and copy this entire post there.

 

Yes, do this, and post in the General Mechanical Help subforum. There are some very skilled pro techs there.

That said, I would be curious to see the results of an exhaust backpressure test. I wonder if clogged cats are causing issues. Also, have you put a voltmeter on the O2 leads and gotten any raw data from them? Can your computer setup pull live data from the O2s?

 

Clogged cats came to mind when I read your first post. makes me wonder if the lacquer thinner trick might clear some of this up? not advocating just spitballing.

Laquer thinner trick? 

Ive got 5 gallons of laquer thinner, but what is the trick?

I have been unable to pull live data with anything at my disposal.  How do i do the 02 reading with a volt meter?

Assuming it's a 4-wire sensor, you've got two dedicated to the heater and two to the signal. You want to identify the latter two and stick your voltmeter probes into the back of the plug so you can see the readings while the engine is running. What you want is rapid fluctuation between ~0.25V and ~0.75V. If it's slow, or the numbers are well out of that range, you've got issues. Check voltage and ground on the heater circuits while you're in there.

Bmw forums first suggestions were to take it to a guy.

Given the tendency these engines have toward vacuum leaks and the havoc they can cause, I don't necessarily disagree with the idea of a smoke test and live data. I'm surprised you can't read live data with that computer setup - what software are you running exactly?

BTW, Chris and Abel - both of whom have checked in on your thread over at BF - are two of the absolute best BMW diagnosticians I've come across.

Dusterbd13 said:

Laquer thinner trick? 

Ive got 5 gallons of laquer thinner, but what is the trick?

Can be useful for code p0420 when the converter is just below efficiency say cpu throws code below 95% efficiency and your converter is at 94%, roughly a gallon of lacquer thinner to half a tank of gas and drive for about 150 miles or so to get most of it through. it can clean out the converter and get rid of the p0420 code. I did it in my sienna van and it got rid of that one and 4 other codes related to it. Of course this is an at your own risk endeavor but I have done it to two of my cars without any bad side effects. and it fixed both p0420 issues.

Dusterbd13 said:

Bmw forums first suggestions were to take it to a guy.

Be patient ... EVERY forum has a dumbass or two posting in them.

Also, like I offered someone else on this forum before. If you want to pay shipping both ways, I have a scanner that will most likely read O2 live data. Let me know and I will ship it over.

"Bmw forums first suggestions were to take it to a guy."

You might try Doc of Doc's Bimmer Shop in Oxford MS on the phone. He's one of the best but will most likely want the car in person.

In reply to 02Pilot :

Im running pa soft scanner 1.4

The reply i got tjis morning was that this software isnt exactly what i need.  I javent been able to get live data though it, nor have i through torque for some reason(works on every other car ive ever plugged in tp.)

Smoke machine test is definitely next step. Pretty sure i got them all with the nuclear parts swap, but that doesnt mean i missed one, or created a new one.

In reply to Slippery :

I may take you up pn that. First going to research the other scanner reccomend in the bmw forum and see if its something that i can make work for me. Ratjer have my own tool, cost permitting. 

Not a BMW, but my daughter had a similar problem with an early Caddy CTS.  Replaced vacum lines, O2's, etc..... like you did.  Turned out to be the computer, along with the harness to it, also had a bad ground for the O2's.

FINALLY got something to read live data. Nothing seems out of the ordinary until the bank 2 sensor 1 stays at. 4v no matter what. 

Is that dead sensor, or....

So the O2 sensor replacements- were they "universal Bosch" replacements, direct fit Bosch replacements, or OE specific Bosch replacements?

To me, the biggest issue you are seeing is electrical, and since both sensors are giving you errors, that's interesting.  The lack of signal error is more than just a heater problem but the whole sensor is bad. 

I had a '94 164 that used Bosch sensors, and some previous work (not the PO, but some dealer) was rather ham fisted pulling the connectors apart- actually pulling the pins out of the housing.  I replaced them with universal Bosch sensors, being careful to wire them correctly- but when I saw the connector issue- that clearly was the core problem with the error.

Basically, I'm suggesting looking carefully over the replacement sensors, and make sure they are wired right.  

Another thing you can try- unplug the sensors completely.  The car should run reasonably well, not perfect, and of course, there will be a MIL light right away.  But that *should* focus the error that is on those.  If you still have a misfire, that's probably caused by something else (which you've already have looked at dealing with).

Dusterbd13 said:

FINALLY got something to read live data. Nothing seems out of the ordinary until the bank 2 sensor 1 stays at. 4v no matter what. 

Is that dead sensor, or....

Is that 4.0 V or 0.4 V (I see a . in the middle of that).  

4.0 would be a huge problem, since it should never be that high.  0.4V just tells me that something is dead- wiring, sensor, etc.  For some reason, Bosch wiring my show ~0.4V when it's unheated.  And that's all on the internal drivers on the ECU, and not an error.