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Discussion Starter #1
Hi guys I need a little help as my m5 has been playing up and I can't get to the bottom of it.
It seems to have the signs of maf or cps problems as it will go into limp mode at full chat after 5krpm.

I've had several codes pop up over the last couple of months which made me change all the lamba sensors and the bank 1 inlet cps but the problem persists and the same codes keep popping up.

I cleared the errors and drove from Germany to the UK and the following have popped up.

129 - index 73
170 secondary air pump
136 idle speed regulator
144 lamba regulator
145 lamba regulator
92 lamba sensor post cat 1 voltage
93 lamba sensor post cat 2 voltage
13 lamba sensor signal pre cat bank 1

the car feels well down on power, almost "flat", however, I cleaned the mafs today and the power felt much better than before.
when it goes into LOS I have no power at all and literally have to restart the car to be able to drive again.

Inthe past II've had missfire codes with this issue but they haven't reappeared which was a little strange to me.
I've also tried a new set of mafs, non bmw, and had to take them off as the idle was rough and the car didn't like them at all.

So that's my dilemma, please help.
 

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When was the MAFs last replaced? Usually, if they are bad enough to cause the problems, M5 will go into limp mode.
 

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You have some unusual codes. That 129 shows as "Cat Protection Function- Empty Tank or Low Fuel" on my code list, which is one that would cause the limp mode.

Can you read fuel trims?
 

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Discussion Starter #4
Unfortunately I don't have a history of when the mafs were last changed. I was thinking it could be them but I find it odd that the maf doesn't throw up an error code of its own?

129 could simply be the fact that I drive my car from full to reserve on a regular basis. What I don't do is floor it when it's nearly empty as I have read that it would put the car into limp. I'll get some shots up of the analog and digital values to help.
 

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Discussion Starter #5
Sorry about the quality but I can'tget the wifi working on the ddiagnostic computer.










4.50 is the blurred out number.




 

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Discussion Starter #6
I've also had the fuel filter changed before anyone suggests that. It was done after this problem started as part of my servicing regime.
The air filters have also been changed.

I have one more inlet cps to fit and I'm ordering the exhaust cps' as a matter of course as the car is on 126k, even though there aren't any codes.

The replacement lamba sensors aren't genuine bmw but they are oem quality from eurocarparts, however, I have read that some people had issues with non genuine lamba sensors, but I'd like to think the analog values "2" would show if these were at fault.
 

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The fuel trims are suggesting a lean mixture (too much air, not enough fuel). The Analog 1 "Total Requirement (kg/hr)" is your MAF sensor reading; a value of 30 at idle is quite high, so it looks like your fuel-injection management is going into limp mode to prevent a detonation condition.

I suggest you get new MAF's, genuine Bosch should be fine. At the very least it resolve part of the issue and bring out other potential causes for flat running.
 

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Discussion Starter #8
I've just ordered some now mate.
would that be high because of my aftermarket induction filters?

That said, the problem persists with the original air boxes too, so perhaps not.
 

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The fuel trims are suggesting a lean mixture (too much air, not enough fuel). The Analog 1 "Total Requirement (kg/hr)" is your MAF sensor reading; a value of 30 at idle is quite high, so it looks like your fuel-injection management is going into limp mode to prevent detonation.
zed, those lambda integrator numbers have reached the lowere limit of 0.75 because the DME is trying unsuccessfully to pull fuel to get back to stoich, so the engine is running too rich.

OP, the total HLM (air flow) of 30 kg/hr (it would normally be around 19) and the additive and multiplicative adaptions being locked at 0 and 1 are typical of running an alpha-N tune with the MAF's disconnected. Do you have a tune?
 

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Discussion Starter #10
I don't believe so mate but i did reset the adaptions at the same time as clearing the errors
 

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Discussion Starter #11
I'm out for a drive to the parents for easter dinner which should give me a good 60 mile drive. Would it be worth reposting the analog values after to show any difference?
 

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zed, those lambda integrator numbers have reached the lowere limit of 0.75 because the DME is trying unsuccessfully to pull fuel to get back to stoich, so the engine is running too rich.
I was thinking along the lines of an over-estimated mass flow measurement that makes the DME add more fuel than necessary.
 

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Discussion Starter #15
Ok so 40 miles later and it only throws up one code.
its still quite hesitant under load but that was expected.



New values as requested.



[

 

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I'm struggling to make sense of your data. Your air flow and fuel injection time are high for a normal hot idle. Was the a/c on?

The code is saying bank 2 is running so rich the DME can't compensate for it. Which is somewhat supported by the INPA data, but INPA also shows bank 1 is running well. There are only a limited number of faults that can cause just one bank to run rich, like a leaking injector. Another possibility is the B2 O2 sensor is reading a false rich.

Do the top two numbers on the Analogue Values 2 screen jump around at hot idle? In other words, do they vary from 0.2 to 0.8V as they should?
 

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Discussion Starter #17 (Edited)
Air con and blowers were off mate.

As you mentioned O2 sensors ill just explain in layman's terms what sensors went where, (as I had 1 genuine one).
The bank 2 (on my rhd car that's the passenger side) were changed for aftermarket ones. The bank 1 after cat sensor is aftermarket too and the before cat one is genuine bmw. Does this make any difference? I expect not but it builds a picture.

Do the values fluctuate between 0.2 and 0.8? I'll check again in the morning but from what I have noticed before (bare in mind I wasn't looking for it) they didn't change in value by much at all. In fact I was surprised to see bank 1 down at 0.46 as it's always been around 0.75ish

Sorry, I'm sure that's not much help but I'll check the values again first thing to see if they fluctuate when warm. (I'd happily do it now but the neighbours might cry as it's nearly 4 am lol)
 

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Yes, good O2 sensors cycle between 0.2 (lean) and 0.8V (rich) a few times every second.

The sampling rate of INPA is horribly slow so it shows as random changes up and down every sweep. You can use the F8 Select button on the screen to just select the O2 sensors to speed sampling up.

If the voltages are steady around 0.75, then the O2 sensors are reading a steady rich condition and the DME is not able to control the AFR at 14.7:1. This is compounded by fact that the two adaptions shown for each bank are not changing as I would have expected to correct for the rich running, especially the additive ones.

Is the gas mileage bad? Does the exhaust smell rich?
 

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Discussion Starter #19
17 mpg over a run but I drive "spiritedly" on limitless Autobahns and yes it smells very rich on idle.

I made a video of me revving the car and the 2nd line values moved between 1 and 8. Can't upload it though as photo bucket aren't accepting it.
 

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Discussion Starter #20 (Edited)





Values from this morning, no ac or electrical devices on. Had driven 30 miles and just swapped the FSR ( which is a breeze compared to an e46 m3!)
 
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