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E30M3 Race F10 535 R1150Rt M Coupe
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Have a look at the voltage in your D-Fault log. It moves around too much. You'll know when the problem occurred in the log. Do they correspond to when the Voltage was moving?

With your car stationary, rev it a bit. The battery light does not come on when the rev's drop. The battery voltage des not move around. Turn the engine off. The battery light comes on just as the engine stops rotating. Your battery light coming on when there are good rev's on the engine is not normal.

I have 3 BMW's, with 2.0L 2.5L and 3.0L engines. They all use roughly the same amount of air mass at the same speed in cruise conditions. This makes sense as the car needs to be producing a certain amount of energy to keep the car at that cruise speed. The speed is the same, so the amount of energy required is roughly the same allowing for the air coefficient of the car and its weight. The 3.0L engine has a bigger MAF and throttle body to the others, yet it is using roughly the same amount of air as the others. Your E46 is between 20% and 25% low on MAF readings at the cruise speeds in your logs. Don't know why, its just an observation.
Excellent point.

Low load xx speed, CFM is relatively the same, or should be. Regardless of engine.

I'd be looking very carefully at the charging rate before I chased my tail also.
 

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Discussion Starter · #22 · (Edited)
I noticed in your video that the battery light was coming on when you were having the problem. Can't make up my mind if this is a symptom of the cause or a result of the issue. I'm leaning towards it being a symptom of the problem because the alternator will still be spinning and charging until the engine stops. Your "D- Fault" log also shows the battery voltage dropping (14.3V to 12.7V worst case) when ever you have the problem.

Check:
  • Battery connections
  • Tightness of the "Positive" jump start bolt
  • Alternator connections, the big cables.
  • Any and all bolted fuses and the main supply leads to the fuse supply rails.

Your "B- Highway" and "D- Fault" logs both show the MAF values lower than expected for the 2.5L engine at those steady speeds. If you had an under reporting MAF, there should be corresponding high lean total fuel trims. You don't have high lean total fuel trims.

I noted with interest, that you have fitted the M3 fuel rail and injectors with 5 bar fuel pressure. The M3 with the S54B32 engine will have larger injectors than you car. Having them in your car without any DME changes will cause more fuel to be injected than expected. Did you scale the DME to the injectors or other similar change to compensate for the extra fuel being injected? Just looking for a possible extra fuel offset to balance the under reporting MAF idea.
In the video, the battery light flashing while the rpm was higher than 1000, not stalling. Am I missing something?
The battery light could be a symptom or completely unrelated to the power problem. I have always contributed the light coming on to the engine stalling for a fraction of a second due to failed ignition timing or injector pulse width as the engine starts to hiccup and go crazy. When I drop the throttle, the rpm kick up, and the engine "hiccups" (loses 300rpm). The higher the rpm goes, the worse it gets. These hiccups feel like major fuel starvation, yet rebuilding the entire fuel system (no way to test m56 fuel system) did not solve the issue.

DME has been checked professionally. I have checked most components for voltage and signal by back probing with a digital multimeter and checked grounds and hot leads for ohm load and continuity. I have not had the alternator tested; If an electrical short from the alternator or otherwise was causing this issue, why would this only happen under medium to high load and not at idle or very low engine loads?
 

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Discussion Starter · #23 · (Edited)
Have a look at the voltage in your D-Fault log. It moves around too much. You'll know when the problem occurred in the log. Do they correspond to when the Voltage was moving?

With your car stationary, rev it a bit. The battery light does not come on when the rev's drop. The battery voltage des not move around. Turn the engine off. The battery light comes on just as the engine stops rotating. Your battery light coming on when there are good rev's on the engine is not normal.

I have 3 BMW's, with 2.0L 2.5L and 3.0L engines. They all use roughly the same amount of air mass at the same speed in cruise conditions. This makes sense as the car needs to be producing a certain amount of energy to keep the car at that cruise speed. The speed is the same, so the amount of energy required is roughly the same allowing for the air coefficient of the car and its weight. The 3.0L engine has a bigger MAF and throttle body to the others, yet it is using roughly the same amount of air as the others. Your E46 is between 20% and 25% low on MAF readings at the cruise speeds in your logs. Don't know why, its just an observation.
The voltage issue is really strange. The reason I believe this to be a symptom or possibly unrelated is that looking closely at the log data, I notice the voltage definitely does not drop every time the engine power totally fails. Notice line 45 of fault log D where the rpm's were raised basically as high as I can get them to 4,500 rpm. During this time, the voltage remains steady as the battery light flickers.

Could it be a failing voltage regulator? If it were related, what electrical problems could cause a massive issue only during engine load, but not at idle or low engine speeds under 2k? I've gone over the car with a Digital Multi-Meter to check for ground, signal, power, and continuity and had the DME professionally repaired at one point for a no-start electrical issue that has not since occurred. I'm beginning to think it may be related to this 2800 rpm stutter thread. It may be worth throwing money at a DME flash and new pre-cat o2 sensors.
 

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Try unplugging the maf and notice if it does any difference. Else, I would be concentrating in the fuel supply, as you have done work to it and something may be off
Also, the most obvious one, scan the car for codes
 

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Hey, can't find the thread now, but a few years back a owner had engine power problems. Problem was one of the bolted fuses on the fuse bus/box/holder in the back of the glove box was loose. Took him months to find it. 20 minute job to check them to eliminate one possibility. Just remember to disconnect the battery first.
 

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The voltage issue is really strange. The reason I believe this to be a symptom or possibly unrelated is that looking closely at the log data, I notice the voltage definitely does not drop every time the engine power totally fails. Notice line 45 of fault log D where the rpm's were raised basically as high as I can get them to 4,500 rpm. During this time, the voltage remains steady as the battery light flickers.
Line 128 and the next 6 lines show voltage =12.7V which is the battery voltage as the alternator generated none while the engine at 2700 rpm. What can cause the alternator to die during this period? I believe the alternator gets the field energized with 12v from the key turned on, and if the ignition switch one of the pins is glitchy then this can happen. What else this bad pin also supplied the power to and with no 12v it could cause hiccup.

I notice the voltage definitely does not drop every time the engine power totally fails. How do you know this?
 

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M56 alternator field energized current is enable by the DME, and so I believe the DME crashed (due to loss power supply or hardware glitcy) causing alternator output zero voltage and engine hiccup.

M54 alternator energized by the ignition key turned on.
 

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Discussion Starter · #28 · (Edited)
Line 128 and the next 6 lines show voltage =12.7V which is the battery voltage as the alternator generated none while the engine at 2700 rpm. What can cause the alternator to die during this period? I believe the alternator gets the field energized with 12v from the key turned on, and if the ignition switch one of the pins is glitchy then this can happen. What else this bad pin also supplied the power to and with no 12v it could cause hiccup.

I notice the voltage definitely does not drop every time the engine power totally fails. How do you know this?
If we're assuming that the log data is correct then I can point out times such as line 45 where the engine is stuttering at high rpm and the voltage remains steady. This morning, for instance, on cold start and drive the engine could barely rev past 2k until warmed up. Tach bouncing everywhere and the battery light did not come on once. No codes. Tomorrow morning it will be cold and rainy where I'm at in Arizona; perfect day to record the spit show.

As for faulty ignition pin; this is interesting. I'll look into this more and see if I can find a way to test it. I soldered a brand new battery into my keyfob and it died basically overnight. I've determined the problem has to lie in the inducing unit ring around the ignition. I wonder if these two problems could be related somehow?
 

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Discussion Starter · #29 ·
M56 alternator field energized current is enable by the DME, and so I believe the DME crashed (due to loss power supply or hardware glitcy) causing alternator output zero voltage and engine hiccup.

M54 alternator energized by the ignition key turned on.
This makes total sense, but to me, it does not explain why the power issue happens consistently at load whether the voltage drops from the alternator or not. I remain confident this is a symptom rather than a cause and here's why. I am again hesitant to point at the DME because I have recently had the DME professionally repaired (RAM checksum error/no start condition) and tested to function by the talented group at RPM Motorsport. It's important to note that this problem is original to me buying the car and has been persistent since before and after the DME completely failed and was repaired and tested to function as noted above.
 

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Discussion Starter · #30 ·
Hey, can't find the thread now, but a few years back a owner had engine power problems. Problem was one of the bolted fuses on the fuse bus/box/holder in the back of the glove box was loose. Took him months to find it. 20 minute job to check them to eliminate one possibility. Just remember to disconnect the battery first.
Do you mean the relays above the fuses? I tried to take a look at them one time but they are more difficult to get at than the crank sensor. I still have my glovebox taken off so I'll see if I can find a good way to get at them and test them. I've tested every relay and fuse on the vehicle except those 3 or 4 relays!
 

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Discussion Starter · #33 ·
Okay, as it relates to ignition timing I found a good thread where jfoj shares some of his ignition timing information with us. I used OBD Fusion to graph some ignition timing data at 500ms intervals. You can find the data here. The ranges jfoj mention are -5 to +30 and notes that sudden drops are normal and can be simply attributed to coasting. The maximum ranges I have seen are -18 to +32.5. The values seem to correspond nicely to rpm and vehicle speed, but I am unsure if these numbers prove good timing. Can anyone weigh in?
 

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I don't think bad ignition is the cause.
Let's think about why at lines starting #45, the MAF shows a wide open throttle intake air rate when the driver didn't do this? The "WOT" is the root cause but what or who opened the throttle just in a few seconds?
 

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Discussion Starter · #35 ·
Drive-by-wire issue? It seems the DME got commands that the throttle wide opened even if the pedal was not.
Can you record/display the throttle opening value? A glitchy throttle sensor might cause this.
I actually just posted these charts and the first 4 show absolute throttle position in comparison to ignition timing, vehicle speed, and engine rpm.
 

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Discussion Starter · #36 ·
I don't think bad ignition is the cause.
Let's think about why at lines starting #45, the MAF shows a wide open throttle intake air rate when the driver didn't do this? The "WOT" is the root cause but what or who opened the throttle just in a few seconds?
This was me slamming the throttle to kick-down. This boosts the rpm and causes the engine to essentially "redline" around 4500 to 5000 rpm. Note that this is the highest the engine will rev at WOT.

Note this was in my intentional manifestation log. I did this on purpose to try and capture the engine palpitations. Any huge rpm boost is intentional.
 

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Discussion Starter · #39 · (Edited)
Hey folks, it's been a couple of months since I last posted here because there hasn't been much progress. Lately, however, there has been a breakthrough and I've narrowed in on the problem. Since my last post, I have replaced the fuel injectors and ignition coils and taken my car to a well-reviewed indy shop who told me they had absolutely no clue what was wrong with it. Two days ago I took it back into the service center at the dealer. I figured since they accurately diagnosed my no-start condition as a DME failure from a service bulletin a few years ago, they were probably the most well-equipped people in my area to deal with this unique problem. Yesterday I picked up my vehicle and was provided with a sheet and a half of trouble codes, most of which are unrelated. The important codes point towards a MAF adaptation failure and several EKPS module failures. The latter is what concerns me, as I have since I bought the car attributed this problem to a failure in the fuel delivery system. This is somewhat vindicating but mostly annoying because I thought I had rebuilt the entire fuel system and was on to other systems, blissfully unaware until now that this car had an EKPS module due to its former SULEV identity.

From my understanding, the EKPS module monitors certain variables from the fuel pump and issues orders to the fuel pump based on specific commands from the DME. Variable it monitors include but are not limited to: fuel pump speed (actual vs specified), delivery rate l/h, fuel pump current, and fuel pump voltage. If I'm correct, it is also meant to control the speed of the fuel pump. How it does this and to what extent the DME is involved in this process I do not know. I imagine it controls the voltage to the fuel pump to variate its speed based on sensor data stored in the DME. Non-SULEV E46 vehicles do not have an EKPS module and rely on a switch relay to control the fuel pump. This means that in standard M54 and S54 vehicles the fuel pump is either in a state of ON/OFF and runs at full chat when in ON state, utilizing the fuel pressure regulator to create linear pressure at the fuel rail and the fuel return line to relieve excess pressure.

The dealer recommended I replace the MAF and EKPS module which will need programming, then proceeded to give me a 2 grand invoice. Typical dealership stuff. I figure I can get this done for less than half that amount. The MAF is no problem; The real problem is the EKPS module. In typical SULEV fashion, I cannot find much information on this subject. My thinking is this; I will delete the EKPS module and wire in a standard relay to the original relay location. Will this cause issues with the DME? The wires coming out of the back of the EKPS module don't seem to add up which makes me a tad uncomfortable about trying to match and splice them together. Another option is to replace the EKPS module and have it programmed as the dealer suggested, but I'm not confident it will cure the ailment if there is a miscommunication between the EKPS Module and the new fuel pump. I currently am using a 5 bar fuel system out of an M3, which is intended to operate with a standard relay. I need some suggestions! Can I simply add a relay and leave it in the EKPS module?

I'm not sure what happened to this vehicle. I can only assume it was struck by a bolt of lightning in the worst place. Almost every electrical system on this vehicle has been fried with checksum errors. The DME, Oil Level Sensor, EKPS, and GM5 central locking module have all had catastrophic electrical failures. Maybe that just my luck. Anyways, I can post pictures of the fault memory list that I received from the dealer, as well as diagrams of the EKPS module and fuel pump relay system in the non-SULEV models if anyone is interested or think they will help. Cheers!
 
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