Just bought a 1997 528i with 91k miles and stick at auction. Misfiring.

**Donut0389** · 03-11-2019, 08:50 PM

Title says it. My beater E28 is on its way out and in searching for a replacement I found a manual 1997 528i that was going up for auction. Listed issues were a cel, misfire, and oil leak. Snagged it for $1300. Only code currently showing up is misfire cylinder 2. Here's what I've done so far...

Oil leak is standard valve cover gasket issues. Doesn't look too serious so that project goes on the backburner.
Removed a crappily installed cold air intake. Previous owner was kind enough to leave the stock plumbing in the trunk.
Temporarily sealed cracks in the rubber baffling just after the MAF. Need to find a new one but it's OKay for now.
Swapped coils around...misfire still on 2.
Swapped plugs around...misfire still on 2.
Plug that was originally on 2 appears as if it just wasn't firing. The rest have your standard wear from use. Plug on 2 is clean as if it's getting fuel but is not getting spark. Def not oil or coolant fowled.

Came here to get opinions from you guys.

**BimmrMeUpSnotty** · 03-11-2019, 09:16 PM

Move the coil and see if that was it.

**Donut0389** · 03-11-2019, 09:34 PM

Originally Posted by BimmrMeUpSnotty

Move the coil and see if that was it.

Already did. Moved coils from 2 to 3 and 3 to 2. Misfire still on 2. Moved plugs from 2 to 1 and 1 to 2. Misfire still on 2.

The stand out feature in this is that the plug that was originally on 2 is varnished. Not oil fouled or coolant fouled. Just varnished like it isn't firing. I think after work tomorrow I'm going to see what I can do to test if the harness for coil 2 is supplying power.

**BimmrMeUpSnotty** · 03-11-2019, 10:07 PM

Well, that’s what the moving of the coil was for, so at least now, you know that all the coils are good, and it’s in the harness. All the ground straps are on good I take it? Probe the harness from both ends, check for continuity.

**Donut0389** · 03-11-2019, 10:15 PM

There's a large ground strap by coil 1 that is in good shape and connected. There's also a brown single wire that comes from the harness and grounds near coil 3. Also in good shape and connected. Where is the other end of the harness? I know where the DME is mounted but I don't have an E39 manual yet. Does the harness connect back at the DME or is there another junction somewhere?

**BimmrMeUpSnotty** · 03-11-2019, 10:40 PM

The harness plugs into the DME, a white plug, and a black plug. Some harnesses will have a grey plug instead of black, no need for the manual, pull the cabin filter out of the way and unplug the harness so you can check continuity.

Copped this from another site a while back.

One pin from every coil pack plug goes to pin #6 on the square black DME side plug.
One pin from every coil pack plug goes to the r/w wire on the white 2-pin connector.
One pin from coil pack plug cyl#1 goes to DME plug pin #3
One pin from coil pack plug cyl#2 goes to DME plug pin #2
One pin from coil pack plug cyl#3 goes to DME plug pin #1
One pin from coil pack plug cyl#4 goes to DME plug pin #9
One pin from coil pack plug cyl#5 goes to DME plug pin #8
One pin from coil pack plug cyl#6 goes to DME plug pin #7

**Donut0389** · 03-12-2019, 04:51 PM

Update. Did a quick test before work this morning. Unplugged the coil on cylinder 2 while idling. No change in idle. So either the harness or the DME has gone bad and the coil is not getting signal from the DME. Going to test continuity on the harness right now.

Update 2. Did some continuity tests. It looks like there is continuity where there should be on the harness. So then I did a voltage test with the car running. Three pins per coil. 15, 4a, and 1. On cylinder 2 the harness is feeding straight alternator voltage in 15/4a and 15/1 circuits. So then I unplugged the harness from cylinder 1 and got a reading there. Engine started running worse. Straight alternator voltage on 15/4a. But 1.0-1.5 volts on 15/1.

**edjack** · 03-12-2019, 06:36 PM

You need a true RMS meter (or a scope) to measure the voltage on pin 1; I don't know what the spec is, but I suspect it's a variable-duty cycle pulse train.

A generic DMM will give a bogus reading.

If there is no pulse train with the engine running, could be wiring, or the driver transistor in the DME that fires the coil.

**Donut0389** · 03-12-2019, 06:50 PM

What has my attention is that pin 15 is power. Looks like 4a is ground because it always reads alternator voltage regardless of coil harness. That means 1 is the firing circuit. On cylinder 1 you get an ~1 volt readout on a multimeter. I know that's not the proper tool to measure things so that number by itself is meaningless.

But when you test cylinder 2, coil harness pin 1 reads alternator voltage constant as if the firing circuit is shorted.

**Donut0389** · 03-12-2019, 08:14 PM

Another update. Did another volt meter test. With the harness disconnected from the DME, no short on the plug for coil 2. Harness connected to DME port, Pin 1 reads the same resistance to Pin 15 as Pin 4a. Gonna call up the local BMW dealership tomorrow to price out a new DME. Pulled the DME for a visual inspection. Nothing physically out of the ordinary like burned pins/plug ports. Will take a closer look at it all tomorrow when I have better lighting conditions.

**cnn** · 03-12-2019, 08:24 PM

You may want to do a compression test...

**Donut0389** · 03-12-2019, 08:59 PM

Originally Posted by cnn

You may want to do a compression test...

I have none of the other symptoms of blown rings. Exhaust is very slightly steamy when you first start it up and does not get worse with throttle. Spark plug that was originally on cylinder 2 when I bought it had no oil fouling. It was just slightly varnished like it had fuel dumped on it. As for power loss? Well the coil isn't getting a usable signal from the DME. So I'm losing power purely because I'm running on 5 cylinders.

**mattmar1** · 03-13-2019, 08:14 AM

compression test is easy enough to accomplish just as surety check. DME spark plug mosfets can fail, but it is rare. if you do ascertain that it is the DME, id look in to getting a used DME and having it cloned off of your original one, it'd save you cost over getting a new one from BMW and going thru all the new DME expense and programming.

**Donut0389** · 03-13-2019, 08:36 AM

Originally Posted by mattmar1

compression test is easy enough to accomplish just as surety check. DME spark plug mosfets can fail, but it is rare. if you do ascertain that it is the DME, id look in to getting a used DME and having it cloned off of your original one, it'd save you cost over getting a new one from BMW and going thru all the new DME expense and programming.

Buying a compression tester today. Perfect excuse to add one to my tool set.

As for the DME...holy ****. Just called a dealership. ONE THOUSAND EIGHT HUNDRED DOLLARS. Just for the DME. Already found a site that I can either send them a used DME with my original EWS unit and keys and they sync the three and send them back. Or I can buy a refurbished DME from them that has been reconfigured for an EWS bypass.

**mattmar1** · 03-13-2019, 12:29 PM

why go for an EWS bypass? ill look later for who i have used previously, but having your old DME cloned to another one (if that is the problem), everything will be form fit and function to your car, no work arounds.
just for grins, have you swapped the injector with another cylinder?

**Donut0389** · 03-13-2019, 12:33 PM

Why disable the EWS? Less stuff to fail later. Not fond of the idea that a miscommunication between the EWS and the DME can make my car a lawn ornament. Buying used DMEs off Ebay for them to reconfigure is a crap shoot as to how long they will last. And then thier refurb DMEs still require your EWS and key be sent in so they can program it all.

EWS bypass DME is the least hassle with the highest chance of not getting screwed and costs the same as a standard refurb DME.

**ross1** · 03-13-2019, 01:02 PM

M52 spark plugs 001.jpgVarnished, like this, 4th from left ?

**Donut0389** · 03-13-2019, 01:54 PM

Nope. When I say "varnished" what I mean is that it looked like it had never fired. No soot. No gunk. No corrosion. The end of the plug was just slightly off color like it had been repeatedly sprayed with fuel that was then allowed to dry out. Looked wet but it wasn't actually wet.

**ross1** · 03-13-2019, 02:16 PM

Good, that one was burning coolant

**Donut0389** · 03-13-2019, 02:30 PM

Good news! Compression test came back good on 2. 180 first pass. 200 second pass.

Bad news! I need a new DME. Tested from pin 1 (coil circuit for coil 2 according to what I found online) on the main DME harness plug against all the other pins. No short in the harness. So it looks like the circuit for 2 failed internally.

**mattmar1** · 03-13-2019, 02:58 PM

if youre willing to take it on, the mosfet driver in the DME can be replaced.
the DME isnt a plug and play thing. either way you go, new or used, the DME needs to be matched to your car
going the cloning route, just the replacement and old DME need to be sent it, the memory of the old DME is dumped, the replacement DME is reprogrammed with the data from the old DME, both are sent back to you, the replacement DME is installed and vroom vroom.
just my $.02 worth.

**Donut0389** · 03-13-2019, 04:45 PM

Took the cover off the DME. Yep. Mosfet for cylinder 2 is melted with slight heat damage to an adjacent component.

**mattmar1** · 03-13-2019, 05:26 PM

heres one place thats cheaper than a new one, or a used one with cloning.

https://circuitboardmedics.com/2000-...epair-service/

**Donut0389** · 03-13-2019, 05:44 PM

Originally Posted by mattmar1

heres one place thats cheaper than a new one, or a used one with cloning.

https://circuitboardmedics.com/2000-...epair-service/

My DME is an MS41.1. I was gonna use these guys: https://www.rpmmotorsport.net/

They don't do repair jobs but they do have refurbished DMEs. Price will work the dust off my credit card but the car's worth it.

Something I did not mention is that the coils are not stock. They're Bavarian Autosport coils. No idea what sort of reliability they have. They look practically brand new like previous owner replaced them thinking it would fix the misfire.

**ross1** · 03-13-2019, 08:35 PM

Not a fan of those red coils. I wouldn't be surprised to find they are the cause and CERTAINLY wouldn't use them after this.
If you post in the genl mech help section you may get a reply from a fellow there capable of diagnosing your DME and cloning a used one.
I believe you can check the coil drivers yourself, I remember seeing an ohm value for them once.
EDIT: "Took the cover off the DME. Yep. Mosfet for cylinder 2 is melted with slight heat damage to an adjacent component"
I see you've found it.
I've recently been playing with SMD soldering. If this isn't too tiny I'd be happy to have a crack at it provided the component(s). No guarantee of success but at the end of the day worst case is it's still NG and you're out a quarter for the MOSFET.
OR, I also have a spare known good 41.1 DME I'd sell at the going rate as a core