Mosfets, codes and clouds

R.G.

Lieutenant
Nov 17, 2016
669
325
0
Henderson, NV
Ride
E92 335, F10 M5
Helping a buddy with his 2007 N54. Logs were showing hpfp crapped out and codes corroborated it. So, a few hours later a new pump was swapped in. Valve cover also replaced same day. Primed the pump, test drove it and no issues.

High five.

Gassing it on the way back from the test drive car stutters a bit, and gave it a bit more gas to get it to misfire so we could check what cylinder. Flip car off and won't turn over. Start logging and rail pressure at 80 psi. Think the pump must be a dud and apparently my buddy recognized some other codes and another mosfet burnt.


New pump arrives, installed, mosfets replaced, swapped hpfp rail sensor, reset adaptations via mhd only.
Fuel trims max negative
AFR's peg at 10.xx
Rail pressure drops from 6-700 to 100 psi
Code present is 29f1
Plumes of exhaust smoke after a minute


Any guesses?

Car is 91 octane RB turbo basic bolt ons etc.
 

Mzfhartge

Specialist
Aug 17, 2017
52
17
0
Somerville, Ma
Ride
07 bmw 335i
Helping a buddy with his 2007 N54. Logs were showing hpfp crapped out and codes corroborated it. So, a few hours later a new pump was swapped in. Valve cover also replaced same day. Primed the pump, test drove it and no issues.

High five.

Gassing it on the way back from the test drive car stutters a bit, and gave it a bit more gas to get it to misfire so we could check what cylinder. Flip car off and won't turn over. Start logging and rail pressure at 80 psi. Think the pump must be a dud and apparently my buddy recognized some other codes and another mosfet burnt.


New pump arrives, installed, mosfets replaced, swapped hpfp rail sensor, reset adaptations via mhd only.
Fuel trims max negative
AFR's peg at 10.xx
Rail pressure drops from 6-700 to 100 psi
Code present is 29f1
Plumes of exhaust smoke after a minute


Any guesses?

Car is 91 octane RB turbo basic bolt ons etc.

Try to flash another map, sometimes 29f1 is a tune problem where it disable the hpfp
 
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[email protected]

Lieutenant
Nov 5, 2016
596
606
55
Bay Area
If you are getting plumes of smoke, and pegged trims 10.x AFR. One of the injectors is stuck open is my guess. We had one do it, and it literally filled the exhaust with unburned fuel. Start it, shut it off, and quickly pull the plugs if that is the issue, one will be very wet, if the injectors are old, just replace them all.
 
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Bmwfixerguy1

Lieutenant
Jun 5, 2017
873
288
0
Ride
07 335i MT
Pull plugs and see what in is soaked. Could be a stuck injector.
Change oil if so as well it might dilutes the oil with fuel
 
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R.G.

Lieutenant
Nov 17, 2016
669
325
0
Henderson, NV
Ride
E92 335, F10 M5
Try to flash another map, sometimes 29f1 is a tune problem where it disable the hpfp
Nah, tried several maps, no dice.

Pull plugs and see what in is soaked. Could be a stuck injector.
Change oil if so as well it might dilutes the oil with fuel

If you are getting plumes of smoke, and pegged trims 10.x AFR. One of the injectors is stuck open is my guess. We had one do it, and it literally filled the exhaust with unburned fuel. Start it, shut it off, and quickly pull the plugs if that is the issue, one will be very wet, if the injectors are old, just replace them all.


Thanks for the feedback. It threw me off seeing both bank trims pegged if it was a single injector but will have him swap the injectors and see if it resolves.
 

R.G.

Lieutenant
Nov 17, 2016
669
325
0
Henderson, NV
Ride
E92 335, F10 M5
So, injectors being index one the car was towed to local BMW. Foreman and I have a discussion on the phone to clarify what they are telling my friend.

Their diagnosis: Because the car runs correctly until it goes closed loop they think it must be something with the DME. Said all hardware checks out and they flashed a stock map while there to confirm not related. When I asked about the possibility of an injector being stuck open, he said if it were, it would be running rough (fouled plug) at start up.

I'm stumped. Never heard of a DME issue that caused these symptoms. Anyone ever heard of something like that?


Just to be sure had my buddy check all the pins on DME to make sure one didn't get pushed in causing weak connection.
 

Bmwfixerguy1

Lieutenant
Jun 5, 2017
873
288
0
Ride
07 335i MT
I feel like I've had something very similar before. Actually I'm sure I have I just don't remember :(

Let me read through the post again and I'll see if anything rings a bell.
 

Bmwfixerguy1

Lieutenant
Jun 5, 2017
873
288
0
Ride
07 335i MT
I'll be honest it's extremely hard to diagnose issues like this via a forum because little details that are really big details get left out a lot.
If your still having issues post up originals faults, what was done then after faults and what was done.

Not do question your ability but a lot of times if their are problems after a repair it can be the repairee ;)
Especially if a dme was open...
 

R.G.

Lieutenant
Nov 17, 2016
669
325
0
Henderson, NV
Ride
E92 335, F10 M5
Issue is the symptoms are inconsistent. It just keeps sending us on different resolution paths. As it sits now, suddenly car is firing up fine, then fuel trims keep drifting negative until they max out forcing open loop.

Pulled the CAS and DME last night and my buddy is upgrading to an MSD81. We’ll update thread if that proves to be resolution
 

Bmwfixerguy1

Lieutenant
Jun 5, 2017
873
288
0
Ride
07 335i MT
Issue is the symptoms are inconsistent. It just keeps sending us on different resolution paths. As it sits now, suddenly car is firing up fine, then fuel trims keep drifting negative until they max out forcing open loop.

Pulled the CAS and DME last night and my buddy is upgrading to an MSD81. We’ll update thread if that proves to be resolution

I really really don't think that's the case but if he's upgrading at least it's a two birds kinda thing. When trims/adaptations drift one way or another it's usually do to a reaction to something, are these the same symptoms as before the valve cover gasket was replaced?

What is the low pressure sensor reading as well? Is it consistent with what low pressure should be?

Try and keep an eye on all relevant sensors as well as not o relevant sensors. I've had bad components pull others down.. oil level sensors we're notorious on the early e60s

If you were closer I'd be willing to help, it's real hard like I said over text
 

R.G.

Lieutenant
Nov 17, 2016
669
325
0
Henderson, NV
Ride
E92 335, F10 M5
I really really don't think that's the case but if he's upgrading at least it's a two birds kinda thing. When trims/adaptations drift one way or another it's usually do to a reaction to something, are these the same symptoms as before the valve cover gasket was replaced?

What is the low pressure sensor reading as well? Is it consistent with what low pressure should be?

Try and keep an eye on all relevant sensors as well as not o relevant sensors. I've had bad components pull others down.. oil level sensors we're notorious on the early e60s

If you were closer I'd be willing to help, it's real hard like I said over text


Yea it’s so random it’s hard to pinpoint

Lp sensor reading is steady. Once OL starts it goes limp mode and runs on 80psi. HPFP swapped twice and it idles perfect at 700 after cold start. AFRs stay steady but trims just keep drifting.

Tried resetting via INPA and get same results. Used Rheingold to confirm O2 voltages correct. Really just makes little sense
 

Bmwfixerguy1

Lieutenant
Jun 5, 2017
873
288
0
Ride
07 335i MT
Yea it’s so random it’s hard to pinpoint

Lp sensor reading is steady. Once OL starts it goes limp mode and runs on 80psi. HPFP swapped twice and it idles perfect at 700 after cold start. AFRs stay steady but trims just keep drifting.

Tried resetting via INPA and get same results. Used Rheingold to confirm O2 voltages correct. Really just makes little sense

Was this the same behavior before VC gasket and fuel pump?
What are the exact faults it's setting?
 

R.G.

Lieutenant
Nov 17, 2016
669
325
0
Henderson, NV
Ride
E92 335, F10 M5
Was this the same behavior before VC gasket and fuel pump?
What are the exact faults it's setting?

So, originally it was just smoking and HPFP was toast. Setting off the typcal fuel pump plaus and showing HPFP psi inconsistent / and triggering limp mode when giving it 50% throttle.

Replaced VC, hpfp and shit was running perfect. deep voice *BUT THEN*


Felt a little shimmy like it wanted to misfire when test driving. Gassed it a bit more to get it to trigger the cylinder specific code.
Pulled over, flipped it off and it wouldn't turn over when trying to re start.

Some random dme code that my buddy said he recognized from the last mosfet non sense so dme was pulled, mosfets replaced and now these issues.
 

R.G.

Lieutenant
Nov 17, 2016
669
325
0
Henderson, NV
Ride
E92 335, F10 M5
Had it towed to BMW because after the dme mosfets replaced and re installed it wasn't adjusting AFR's at all. Thinking it was injectors.

It would peg STFT -34% as soon as it would try to go closed loop. Then shut down hpfp and go in to limp mode. NOTHING changed since then. Suddenly car is going closed loop and trying to regulate but trims just keep drifting towards negative and then inevitably goes OL
 

Bmwfixerguy1

Lieutenant
Jun 5, 2017
873
288
0
Ride
07 335i MT
That's kinda where I'm going with this, after soldering inside the DME it's now doing something fairly odd it wasn't doing before. Lol
What is your friends small circuity soldering ability? If he got solder in a spot it shouldn't be who knows what kind stuff it could cause, right.
I think it's better to see what happens after the msd81 upgrade and go from there :)

Where are you located again?
 

R.G.

Lieutenant
Nov 17, 2016
669
325
0
Henderson, NV
Ride
E92 335, F10 M5
That's kinda where I'm going with this, after soldering inside the DME it's now doing something fairly odd it wasn't doing before. Lol
What is your friends small circuity soldering ability? If he got solder in a spot it shouldn't be who knows what kind stuff it could cause, right.
I think it's better to see what happens after the msd81 upgrade and go from there :)

Where are you located again?


Yea, fingers crossed. Need to focus on my car LOL. Soldering was done by a retired air force electrician, but doesn't rule out some sort of error made. I agree with ya that the upgrade will at minimum avoid more inevitable mosfet nonsense. 07's are such a headache.

Located in Vegas suburb
 

Bmwfixerguy1

Lieutenant
Jun 5, 2017
873
288
0
Ride
07 335i MT
Yea, fingers crossed. Need to focus on my car LOL. Soldering was done by a retired air force electrician, but doesn't rule out some sort of error made. I agree with ya that the upgrade will at minimum avoid more inevitable mosfet nonsense. 07's are such a headache.

Located in Vegas suburb

Yea fingers crossed for ya. If nothing else it at least rules that out, cheaper than the dealer. A dme from my dealer is like 2300 last time I checked. And he gets an upgrade from it.
 

V8bait

Sergeant
Nov 2, 2016
495
757
0
Texas
MOSFET's usually fail and damage injectors. I hope you replaced all of the mosfets, not just the failed one. The person doing the repair should have used an air station, not an iron, if they used an iron 9/10 chance they ruined something. These things are important for a proper repair.