Repairing a 'fried' N54 MSD80 DME

Roy Cormier · 08-20-2012, 09:25 PM

So a couple weeks back I was out for a nice Sunday drive in my 335i, I downshifted into 3rd, floored it, and heard an insanely loud backfire. Then that damned half-engine light comes on and the car barely makes it home.

After reading the codes with the Cobb Accessport I decided to probe the pins on the DME connector to try to figure out what was going on.

The Transistor for injector #5 was toast, and after I saw what a replacement DME would cost from the dealer I figured I better just fix it myself. I took the part number off the MOSFET, spent $2.00 for a new one from digi-key and after a little bit of work with the hot-air gun I was back in business.

I was getting the following codes:
30bb - DME digital motor electronics, internal failure
0305
0306
0304
0300
29d1 - Misfire Cyl 5
29d2 - Misfire Cyl 6
29d0 - Misfire Cyl 4
29d9 - something about misfiring with low fuel level
29cc - Misfire Multiple Cylinders

So heres a few pictures in case anyone is unfortunate enough to have a similar problem occur.

Transistor pins were shorted together

Transistors labeled:

I stopped taking pictures after this point. But basically you just remove the bad MOSFET and install a new one in its place.

Then after everything was closed back up, it started and ran great.

themyst · 08-20-2012, 09:27 PM

Awesome post! Thanks for sharing. Do you happen to have a full diagram of all the various parts on the DME board that you used for reference?

Ilma · 08-20-2012, 09:30 PM

OK....so I happen to know that MOSFET stands for metal oxide semicondutor field effect transistor.

But I don't think I could ever pull off what you just did

Kudos man!

I think that is a first on this forum

Roy Cormier · 08-20-2012, 09:33 PM

I think I do, actually. I spent a while tracing pins back to components on the board while I was waiting for my parts to ship. Then I labeled them on one of the images, I'll see if I can find it at work tomorrow.

The transistors in question are IRF644B's.

BMV///M3 · 08-20-2012, 09:35 PM

That's great work man! What map were you running on COBB?

Roy Cormier · 08-20-2012, 09:40 PM

Stage2+FMIC aggressive, I believe. The transistor got fried due to a wiring harness issue though. Whoever owned this car before me must have been a complete idiot, either that or whatever shop they had work on it sucked. They must have knicked the wiring harness when doing some work, so nearly all of the coil/injector wiring had been slightly cut. But it was under the engine cover so I never noticed until something blew.

The car has been a complete nightmare to own so far, although I love driving it everyday.

iBoost · 08-20-2012, 09:44 PM

nice job

themyst · 08-20-2012, 10:00 PM

Quote:

Originally Posted by stealthtt

I think I do, actually. I spent a while tracing pins back to components on the board while I was waiting for my parts to ship. Then I labeled them on one of the images, I'll see if I can find it at work tomorrow.

The transistors in question are IRFW644B's.

If you could post a DIY or the board layout, that would help us immensely!

themyst · 08-20-2012, 10:00 PM

Quote:

Originally Posted by Ilma

OK....so I happen to know that MOSFET stands for metal oxide semicondutor field effect transistor.

But I don't think I could ever pull off what you just did

Kudos man!

I think that is a first on this forum

If the DME is already fried, you don't have much to lose!

cn555ic · 08-20-2012, 10:04 PM

What were the codes that lead you to the dme MOSFET?

nitehawk · 08-20-2012, 10:39 PM

Now that's something you dont see everyday!

Myaddiction · 08-20-2012, 11:43 PM

I would have bought a used DME and thought I was clever for that.
Impressive!

D_Smiderreen · 08-21-2012, 12:41 AM

I wish I could give you rep points

Elie335 · 08-21-2012, 02:32 AM

can you please tell what code were you throwing ?

cstavaru · 08-21-2012, 04:29 AM

Nice job !

messi · 08-21-2012, 05:51 AM

Wow. You should working for samsung

Roy Cormier · 08-21-2012, 06:27 AM

The codes were:
30bb - DME digital motor electronics, internal failure
0305
0306
0304
0300
29d1 - Misfire Cyl 5
29d2 - Misfire Cyl 6
29d0 - Misfire Cyl 4
29d9 - something about misfiring with low fuel level
29cc - Misfire Multiple Cylinders

enrita · 08-21-2012, 07:09 AM

amazing man great job!

manolooo · 08-21-2012, 07:19 AM

Props

scottro · 08-21-2012, 10:18 AM

Nice work! Do you see any pins on the board where they may have left off a JTAG header and one could be soldered on?

Roy Cormier · 08-21-2012, 11:05 AM

Quote:

Originally Posted by scottro

Nice work! Do you see any pins on the board where they may have left off a JTAG header and one could be soldered on?

I'm not sure yet. Out of boredom I started tracing out some of the BGA pins on the TC1796, but I haven't gotten around to finishing that yet.

Theres a much higher resolution of the board HERE if anyone is interested.

These are the BGA balls that I was working on tracking down:

jb's335 · 08-21-2012, 11:11 AM

Very cool, your information is greatly appreciated!

BTW I love VR-4's. I have met a lot of previous VR-4 owners now with 335i's, interesting how that works out lol. Twin turbo 6 to twin turbo 6!

08-20-2012, 09:25 PM	#1
Roy Cormier Private 40 Rep 70 Posts Drives: E92 M3, E92 335i Join Date: Feb 2012 Location: Green Bay, WI iTrader: (0) Garage List E92 BMW 335i [0.00] E92 BMW M3 [0.00]	Repairing a 'fried' N54 MSD80 DME So a couple weeks back I was out for a nice Sunday drive in my 335i, I downshifted into 3rd, floored it, and heard an insanely loud backfire. Then that damned half-engine light comes on and the car barely makes it home. After reading the codes with the Cobb Accessport I decided to probe the pins on the DME connector to try to figure out what was going on. The Transistor for injector #5 was toast, and after I saw what a replacement DME would cost from the dealer I figured I better just fix it myself. I took the part number off the MOSFET, spent $2.00 for a new one from digi-key and after a little bit of work with the hot-air gun I was back in business. I was getting the following codes: 30bb - DME digital motor electronics, internal failure 0305 0306 0304 0300 29d1 - Misfire Cyl 5 29d2 - Misfire Cyl 6 29d0 - Misfire Cyl 4 29d9 - something about misfiring with low fuel level 29cc - Misfire Multiple Cylinders So heres a few pictures in case anyone is unfortunate enough to have a similar problem occur. Transistor pins were shorted together Transistors labeled: I stopped taking pictures after this point. But basically you just remove the bad MOSFET and install a new one in its place. Then after everything was closed back up, it started and ran great. __________________ E92 M3 - Space Gray \| E92 335i - Alpine White If you can leave black marks on a straight from the time you exit a corner till the time you brake for the next turn....... Then, you have enough horsepower. Last edited by Roy Cormier; 03-16-2017 at 01:22 PM.. Reason: updated picture links
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08-20-2012, 09:27 PM	#2
themyst Major General 177 Rep 6,631 Posts Drives: '16 MK7 GTI Join Date: Feb 2009 Location: NYC iTrader: (8)	Awesome post! Thanks for sharing. Do you happen to have a full diagram of all the various parts on the DME board that you used for reference? __________________ E90 LCI N54 6AT
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08-20-2012, 09:30 PM	#3
Ilma Colonel 184 Rep 2,841 Posts Drives: 2008 135i Join Date: Nov 2008 Location: Mississauga iTrader: (0)	OK....so I happen to know that MOSFET stands for metal oxide semicondutor field effect transistor. But I don't think I could ever pull off what you just did Kudos man! I think that is a first on this forum
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08-20-2012, 09:33 PM	#4
Roy Cormier Private 40 Rep 70 Posts Drives: E92 M3, E92 335i Join Date: Feb 2012 Location: Green Bay, WI iTrader: (0) Garage List E92 BMW 335i [0.00] E92 BMW M3 [0.00]	I think I do, actually. I spent a while tracing pins back to components on the board while I was waiting for my parts to ship. Then I labeled them on one of the images, I'll see if I can find it at work tomorrow. The transistors in question are IRF644B's. __________________ E92 M3 - Space Gray \| E92 335i - Alpine White If you can leave black marks on a straight from the time you exit a corner till the time you brake for the next turn....... Then, you have enough horsepower. Last edited by Roy Cormier; 08-22-2012 at 12:39 PM..
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08-20-2012, 09:40 PM	#6
Roy Cormier Private 40 Rep 70 Posts Drives: E92 M3, E92 335i Join Date: Feb 2012 Location: Green Bay, WI iTrader: (0) Garage List E92 BMW 335i [0.00] E92 BMW M3 [0.00]	Stage2+FMIC aggressive, I believe. The transistor got fried due to a wiring harness issue though. Whoever owned this car before me must have been a complete idiot, either that or whatever shop they had work on it sucked. They must have knicked the wiring harness when doing some work, so nearly all of the coil/injector wiring had been slightly cut. But it was under the engine cover so I never noticed until something blew. The car has been a complete nightmare to own so far, although I love driving it everyday. __________________ E92 M3 - Space Gray \| E92 335i - Alpine White If you can leave black marks on a straight from the time you exit a corner till the time you brake for the next turn....... Then, you have enough horsepower.
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08-20-2012, 09:35 PM	#5
BMV///M3 Major 419 Rep 1,068 Posts Drives: BMW f80 M3 Join Date: May 2012 Location: CA iTrader: (1)	That's great work man! What map were you running on COBB?
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08-20-2012, 09:44 PM	#7
iBoost Retired e90post Member 135 Rep 3,038 Posts Drives: real slow Join Date: Nov 2009 Location: Las Vegas iTrader: (13)	nice job
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08-20-2012, 10:04 PM	#10
cn555ic 441 Rep 18,331 Posts Drives: 335i Join Date: Jun 2007 Location: US iTrader: (6)	What were the codes that lead you to the dme MOSFET?
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08-20-2012, 10:39 PM	#11
nitehawk Lieutenant Colonel 102 Rep 1,903 Posts Drives: e92 335i 6MT Join Date: May 2011 Location: Toronto iTrader: (15) Garage List E92 BMW 335i [9.00] E92 BMW 335i \| Retired [10.00]	Now that's something you dont see everyday!
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08-20-2012, 11:43 PM	#12
Myaddiction Second Lieutenant 87 Rep 286 Posts Drives: X6M Join Date: Nov 2011 Location: San Diego CA iTrader: (0) Garage List 2015 BMW M4 [0.00]	I would have bought a used DME and thought I was clever for that. Impressive!
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08-21-2012, 12:41 AM	#13
D_Smiderreen Banned 13 Rep 156 Posts Drives: Please delete my account Join Date: Nov 2009 Location: please delete my account iTrader: (1)	I wish I could give you rep points
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08-21-2012, 02:32 AM	#14
Elie335 ايلي ٣٣٥ هاهاها 88 Rep 1,448 Posts Drives: Vorsteiner e92 Join Date: Jun 2009 Location: Leb iTrader: (1)	can you please tell what code were you throwing ? __________________ Recent exterior modifications
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08-21-2012, 04:29 AM	#15
cstavaru Brigadier General 313 Rep 3,262 Posts Drives: 2009 335i M Sport Sedan 6MT Join Date: Aug 2008 Location: Bucharest, Romania iTrader: (0)	Nice job ! __________________ Mods(click): Cobb + RB Turbos \| Aquamist HFS-4 Meth \| Drexler LSD \| Bilstein B12 Pro-Kit \| Custom K&N Apollo Intake \| Wagner Intercooler \| Macht Schnell Downpipes \| BMW Performance Power Kit \| BMW Performance Exhaust \| BMW Performance Short Shifter \| M3 Subframe Bushings \|
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08-21-2012, 05:51 AM	#16
messi First Lieutenant 15 Rep 368 Posts Drives: 2009 E92 335i MSport Coupe 6AT Join Date: Jun 2011 Location: Trinidad iTrader: (1)	Wow. You should working for samsung __________________ Procede rev2.5se;Er Fmic; BMW PE
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08-21-2012, 06:27 AM	#17
Roy Cormier Private 40 Rep 70 Posts Drives: E92 M3, E92 335i Join Date: Feb 2012 Location: Green Bay, WI iTrader: (0) Garage List E92 BMW 335i [0.00] E92 BMW M3 [0.00]	The codes were: 30bb - DME digital motor electronics, internal failure 0305 0306 0304 0300 29d1 - Misfire Cyl 5 29d2 - Misfire Cyl 6 29d0 - Misfire Cyl 4 29d9 - something about misfiring with low fuel level 29cc - Misfire Multiple Cylinders Last edited by Roy Cormier; 08-21-2012 at 06:34 AM.. Reason: adding code descriptions
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08-21-2012, 07:09 AM	#18
enrita Major General 161 Rep 7,378 Posts Drives: 335i - Big turbos Join Date: Sep 2008 Location: Italian in Sweden iTrader: (0)	amazing man great job! __________________ 07 335i AT - MOTIV 750 - MHD E85 BMS flash - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Snow Stg. 3 - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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08-21-2012, 07:19 AM	#19
manolooo Second Lieutenant 48 Rep 205 Posts Drives: '21 X4 M40i Join Date: Feb 2012 Location: NJ iTrader: (1) Garage List 2021 BMW X4 M40i [0.00]	Props
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08-21-2012, 10:18 AM	#20
scottro Second Lieutenant 17 Rep 205 Posts Drives: E70 X5M Join Date: Sep 2011 Location: Phoenix, AZ iTrader: (0)	Nice work! Do you see any pins on the board where they may have left off a JTAG header and one could be soldered on?
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08-21-2012, 11:11 AM	#22
jb's335 Big Boost Addict 52 Rep 689 Posts Drives: AW e92 335 Join Date: Aug 2008 Location: Lima, OH iTrader: (12)	Very cool, your information is greatly appreciated! BTW I love VR-4's. I have met a lot of previous VR-4 owners now with 335i's, interesting how that works out lol. Twin turbo 6 to twin turbo 6! __________________ FFTEC 62mm...yeah I think that about does it.
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