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Discussion Starter · #1 ·
Hello to everyone, i'm fresh owner of M5, and have a power loss problem.
Form about 3000 RPM on WOT, massive powerloss.
Sometimes goes to Limp mode, closes throttlebodys

Already changed:
-Fuel Pump Pierburg 5bar orginal pump
-Fuel filter
-Fuel regulator 5bar Pierburg
-Spark plugs NGK bkr6equp

After changing sparkplugs the drop in power has increased

Adding logs from TESTO logger ( 2nd gear pull), cant do 3rd gear pull in town


As you can see fuel drops around 2800rpm down, i think problem is still with fueling :/
Vanos system works perfect, temperatures are ok

One time when limp mode appeared and car closed throttlebodys at 5000rpm, after that i checked one error: "129 internal index 73"

Found that 129 errors is "Cat Protection Function- Empty Tank or Low Fuel"

Car have 73 000km orginal milage

Please help, mayby someone already solved isue like that
 

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This won't help a lot, but I can see that the FIRST thing to happen in your datalog is the throttles closing, and all the other parameters follow thereafter. This means it's something NOT logged there that's causing the throttles to close. I also don't see any drop at 2800 RPM that you mention. . . The empty tank error might be a clue; does your gas gauge work properly? Seems like it thinks (or is actually) running out of fuel and is cutting throttle due to that.
 

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Discussion Starter · #3 ·
The problem is always there, no matter if I have little or a lot of fuel.
It would be best to compare the log with another M5.
At 2200rpm the injection time is over 10ms, then it drops to 9ms, shouldn't it increase with rpm?
 

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129 errors is "Cat Protection Function- Empty Tank or Low Fuel"
That is the only code you are getting? Very strange if that is alone, not sure where to begin. What the code is saying is that the O2 reported a very lean condition that could damage the cats, so that is fuel delivery. It normally comes with other codes however, like the fuel trims are cranked right up. Is there a chance the car has a tune in it? If someone has tuned it by cranking up the fuel that would explain why you are not getting fuel codes but the fuel pump can't deliver the right fuel. Even though 5 bars and the specs on the fuel pump seem more than enough my tests show almost no fuel is returned to the tank on a full throttle pull, so really that seems marginal delivery to me.
I will watch your video after you answer those questions, don't want to taint my first view with assumptions.
EDIT: I had a peak and it is not a video, but that is confusing. Start off with the very bottom and the rpm first it goes up then down, so is that actual or just part of the standard graph? It is odd to use the graph scale variable but so be it. Is where the red throttle position 7000 rpm or 7200 or more rpm, that will be a hint if the car is tuned.
 

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I don't have that computer here that can look at bins. Maybe someone else can though. I don't really need to though, I can tell you now either you have a tune or some software corruption. Maybe a bad DME but I doubt that from your first graph. Although the first graph would be more helpful over time instead of RPM and then the rpm graphed. I also can't make heads nor tails out of the load signal, I am used to seeing it represented as a percent, I have no idea what 4.21 represents. It also needs the O2 readings or the air fuel ratio.
Lets start with the simple stuff. Does the check engine light come on? In key position 2 without the engine running, or go to test 2(I think, the one that tests the cluster) in the OBC. If the light, lights then you more than likely have a tune and should start by flashing back to stock. There are a lot of bad tunes out there and you could have one. Anytime you start looking for a problem, first thing is go back to stock so we know what the car is talking about. If your tune changes the air fuel ratio poorly, that could be the issue.
 

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Check comes on on key 2 position. How i can go back to stock tune?
You have to get the DME re-flashed or programed to a stock tune. Available at the dealer for an hour or so. Check first and get a solid quote. It depends what is close to you, independants can do it also, you will just have to check with your local experts. You can do it yourself, but if you have to ask there is a ton of gear and know how you will likely have to get and learn.
Maybe @mgdmb can help you next time he is around. Have not seen him post in a bit but he will be around at some point. Not my specialty for BMW, but I am well versed in Audi-s but it is not the same.
 

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You can do it with WinKFP as well. I've only done it once and it was a couple of years ago, but I'm sure the directions can be found on the interwebz

Since the car doesn't throw a code with the MAFs disconnected, it's tuned for AlphaN (MAFless tune). I was going to suggest unplugging the MAFs and see if its still happens but it seems like it occurs with or without them?

Not too many things will drop the car into limp mode, the drive-by-wire system is the usual culprit. TPS sensors / actuator, etc

M
--

I've been occupied with my E36, was getting it prepped for Laguna Seca today
 

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What else i can check
The two codes extra codes you are getting are for fuel control which generally means the fuel trim has been cranked up to its max rich condition and can't be turned up more. I say generally because the way fuel trims work they can set under a different situation and that is opposite in nature, but with the empty tank code it makes it likely that the car is not getting enough fuel. Those codes can drop the car into limp mode, but that is extremely rare. You should watch the O2 readings in a pull to get some reference. If the O2s are showing lean that is building more lean it could be causing the limp mode.
First though I would run the car with the MAFs unplugged and see if there is a big difference, see if it still goes into limp mode. If it still goes limp, I think I would just replace the two TPS(throttle position senders) at the back of the motor first. They are known to not throw codes and throw the car into limp mode. They are not expensive and are a maintenance/wear item. I replace them on every car I purchase.
 

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Discussion Starter · #12 · (Edited)

That's everything i can log in Testo
3rd gear pull, at 5000 limp mode, cuts off power. I still had the accelerator pedal pressed all the way for a while ( to about 14.03s on log), everything after is driving in limp mode


And here one more also but no WOT , 20-40% gas pedal


As you can see. Lambda integrators 1.25 all the way to 5000 RPM

Everything looks like problem with fueling, i need to check fuel pressure on dyno.

Strange because the fuel pump, filter and pressure regulator are new
 

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How old are the mafs / o2 sensors? Might be worth a smoke test too...
Didn't he disconnect the MAFs? And O2's drop out at WOT. I would assume even with the "MAF test", he would get lousy numbers, just confirming a fuel delivery issue.

Maybe time to open up the plenum and look at the injectors. If the fuel pump is good (I know new, I think he changed it to solve the problem so odds of 2 bad fuel pumps mighty small), it has to be something else.

For the OP, when you take the car out next, pull up the fuel information from the OBC. Don't remember which test it is, someone here will remember. It will show left and right tank in liters of fuel. Fuel should be pushed from left tank to right tank and right tank to engine. Make sure you have the right tank being filled from the syphon pump. And I would double check all of the fuel pump connections and hoses in the tank; make sure nothing is kinked or blocked as well as the fuel line to the engine. It sure sounds like not enough fuel is making its way into the engine.

Regards,
Jerry
 

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As you can see. Lambda integrators 1.25 all the way to 5000 RPM
I beat my head against the wall time in and time again on this topic. Sometimes what looks like there is not enough fuel it is because there is a ton of free air getting in.
Free air means there will never be enough fuel.
The hardest part of any of this is communication, especially when the terms lean and rich are used. I call a car that is adding fuel a lean car but many others seem to call that rich.
Are you only doing this on a dyno, or are you driving the car too?
The only way I know how to communicate this stuff on the net is to have someone drive the car with the MAFs unplugged and to MAF test runs with the MAFs plugged and unplugged.
Best guess is you either have bad MAFs or elbow 17 might be bad or you have some other leak into the high vacuum side. Does not seem like a leak above the throttles.
 

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Discussion Starter · #19 ·
On orginal software. Unpluggend MAFs, deleted adaptations. Smooth driving till fully warmed, then WOT, full power is BACK ! Car revived. On log almost double "kg/h on maf fail mode". Fuel grows all the time to rpm cut off.
So preverious software is probably ALPHA N but someone before me pulugged mafs back.

New BOSCH MAFs ordered.

Thanks for help, you have helped me a lot
 

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So preverious software is probably ALPHA N but someone before me pulugged mafs back.
I warned people about Alpha-N when it first came out, in my book it was a DME lobotomy. The adaptions made when things are not right under that tune will be poor choices because the car can't determine the correct adaption. Alpha might work fine if everything is perfect, but issues come when they are not.
I think you made the smart choice getting rid of it, if for no other reason your car is a lot smarter now. Glad to hear you have broken the back of this problem.
 
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