2003 Z4 3.0 codes P1515

[SystemLord0]

Hi everyone;

I have a 2003 Z4 3.0 120,000 miles with no engine modifications and it runs great and drives great but due to a code i have not been able to pass smog the past year so it’s been sitting. I am worried that if i don’t drive it soon it will be a slow and quite death.

I have always had some issues with an Trouble code popping up randomly (P1515) but until 2 years ago i was able to clear the code and it would not come back for a few month so i could pass smog. Now the code comes back at as soon as the car is ready to smog and it trips the engine light meaning i can’t pass smog in California. All smog values look good.

Initially in 2012 my shop came up with the following:
P1515, Electronic Throttle Position

But back then it only showed once in a while and they could not locate the exact issue.
They also came back with a engine code “RAN BMW CODE 2774 though BMW which came back as E53 X5 ERROR in INST. CLUSTER”. which stumped us.

Flash forward 2-3 years i even went to BMW to have them pull the code and tell me what might have to be done to get it fixed. They were not very helpful and told me it’s an electrical issue and I have to replace the instrument cluster…. I sad thank you and left.

Made it a couple of years longer all the way to 2018 but now the code is coming back so fast/repeatedly that when I get close to all my sensors ready for smog (from cleaning codes) the P1515 flips from pending to engine light on so that I can’t pass smog.

Some online searches come back saying that P1515 is related to electrical “over current” detection but it’s also very vague.

So far I have replaced the accelerator pedal (code still coming), found a leaking hose from the air blower to the engine, Inspected the DISA valve but it looked very clean and solid so I did not replace it.

My next plan was to inspect/replace the throttle body and go over all the air intake hoses one more time.

I am hoping someone has some pointers of what I should look at next or try so I can start going down some kind of systematic list.

I have been using BlueDrive on the OBDII to get my data and i have been getting the P1515 pending trouble code and engine code 2774 (Engine cut off time) and 27A4 (Interface EWS 3.3 - DME).
P1515 stays as pending for a while before setting off the engine light.

Any help would be much appreciated!

Manuel

 

[enuff_zed]

Hi and welcome.
Just curious as to why you are discounting an electrical issue with the instrument cluster, if that is what BMW have told you, and you have had a code saying something similar.
Are you not potentially throwing money at other things when the fault could be exactly what they told you it is?

 

[SystemLord0]

Its true that i have been discounting their results a bit since they seemed not that sure and to just want to get rid of me or a lot of money to change the instrument cluster.

I have been just going off the most common definition of the Electronic Throttle Position since i am able to test/inspect these components. I just felt that if the interment cluster would have issues there would be more issues/warnings overall but i also would not be able to determine if its bad or good except for a visual issues.

I will see if i can at least pull the instrument cluster and inspect it and the cable harness etc.
Back then they quoted so much that it was not a good financial decision compared to the value of the car but i could try getting a used one now a day. (Not sure if it requires re-programming or the sorts but i will start looking into it.)

 

[enuff_zed]

Its true that i have been discounting their results a bit since they seemed not that sure and to just want to get rid of me or a lot of money to change the instrument cluster.

I have been just going off the most common definition of the Electronic Throttle Position since i am able to test/inspect these components. I just felt that if the interment cluster would have issues there would be more issues/warnings overall but i also would not be able to determine if its bad or good except for a visual issues.

I will see if i can at least pull the instrument cluster and inspect it and the cable harness etc.
Back then they quoted so much that it was not a good financial decision compared to the value of the car but i could try getting a used one now a day. (Not sure if it requires re-programming or the sorts but i will start looking into it.)

Any chance you could borrow one from somewhere to slave in?

 

[ph001]

I don’t think it will be the instrument cluster at all. The code for that comes up fairly often and is usually spurious. I’m no expert on the M54 but there is likely to be a throttle position sensor on the throttle body somewhere so I would start with that. Then the throttle body if no luck.

 

[Chris_D]

I was getting that code when i had issues with my tb.
Bought a 2nd hand tb off ebay to test and it confirmed i had a bad tb.

 

[SystemLord0]

I went ahead and replaced the throttle body with a new one; cleaned all the connectors with alcohol spray just to be sure. All the intake hoses on that side seems to be fine but i did replace the rubber air-intake hose with all the joints with a new one as well to be sure (was an original 2002 but still looked good).

Was able to drive around for 7 miles the same day with no codes and was very very hopeful. BUT this afternoon i decided to give it another go and within 2 miles the P1515 was back (pending) and a engine code of 2774 (engine cut off time). (I can only drive about 30MPH with since i have no legal smog and have to stay within my work complex.

I am going to pull the dash now and clean the connectors to check that off the list; if there are no other options then i will have to buy a instrument cluster and give that a try.

As far as i understand there is no throttle position sensor but only the throttle body and the gas pedal which digitally sends the throttle position to the car. I did change the gas pedal once before thinking that might be the source of the P1515 but after replacing it i will got the same error so i ended up returning it (-15%).

I am using BlueDrive OBDII Bluetooth reader but do you think i should invents into a more costly BMW specific unit to possibly find out more?
ETC:https://www.amazon.com/FOXWELL-Automotive-Diagnostic-Transmission-Registration/dp/B019QCG5RE

 

[colb]

Have you tried resetting the throttle adaptions, worth a try, details lifted from another forum
First, with the key removed, sit in the driver's seat and insert the key.

Turn the key to position "2". Position "2" is one position before the car engages and starts.
Wait 10 seconds and then turn the key back to position "0", which is the initial position.

Once again wait 10 seconds and then start the car up.

You should now have your throttle response reset and your driving pattern from this point on will dictate how your throttle response adapts.

Over time your throttle response will once again become lacking and another reset will need to be performed. It is recommended that this be performed every 3-6 months if you feel the need to have your spirited car back.

 

[SystemLord0]

Thanks colb,
I will give that a try and report back; i did unplug the battery when i replaced the throttle body and i just saw a few posts stating that disconnecting the battery might have the same effect since it forces the computer to restart from scratch anyways. But no harm in giving it a try.

Anyone know the part number for the wire harness that is right next to the throttle body? It connects the DISA valve, Throttle control, idle valve and a few others all together. I am wondering if it would be worth changing that out. All the connectors looked clean and sealed but some of the wire shielding is getting old and bridle.

 

[SystemLord0]

Quick update;
Code is back (pending P1515) after driving yesterday for 3 miles and another 3 today it showed up. So cleaning the instrument cluster connectors didn't help nor did resetting the throttle adaption.
I did notice that it smells a bit rich (fuel smell from exhaust) and the engine is a little rough but i am not sure if that's from it just sitting for a long time and not being driven very much.

I went ahead and bought a new DISA valve since i found a few posts saying that a bad DISA can throw all kinds of codes. I did visually inspect it a while back and it looked in great condition but maybe there is a issue with the seals that wasn't obvious.

Running out of ideas; would be a shame to have to scrap the car just because of a non smog related fault....

Ill try the DISA and see if that helps me any.
Anyone else have a good idea?

Add some photos; the original throttle body wasn't very dirty and the flap seemed fine; maybe a hair more play than the new one but for being a 2002 unit....

[UPDATE/EDIT]
I figured i measure the battery one more time; its relatively new 6-month and its measuring 13.31V when the car is off. When i turn on the car (ideal in park) i am getting 13.95V when i rev the car a bit 3000+- RPM i am getting a but over 14V (14.05).
I am wondering if the alternator is bad; just enough to keep the battery chargig a right at the limit.
Can someone tell me what they are getting? I think it should be closer to 16V when the car is running....?
Maybe that's causing the code?
[UPDATE/EDIT]



Thanks,
Manuel

 

[ph001]

Hmmm, this one has me a bit stumped as you appear to have replaced everything I would have suspected. Your battery and alternator voltage sounds fine, although ideally you need to measure the battery voltage after the car has been stood overnight... it should be 12.4 - 12.6V

I’ll do a bit of research on M54 throttle position sensors. I find it a bit odd if it really doesn’t have any as the S54 engine has two!

 

[colb]

Is there any chance that you can view live data with the engine running with your diagnostics readerm, might be worth having a look at the fuel trims to see what they are doing given the smog test fails. If the Maf is misreporting amount of air entering the engine or you had a vacuum leak somwhere between the Maf and the exhaust sensors the latter will be reading unmetered air and tell the ECM that its running lean and get it to add more fuel at the injectors to richen it up. If the Maf is bad or indeed there are air leaks in the system the fuel trims will be high readings and maybe adding 20% more fuel as it tries to compensate for the spurious lean condition. Bad Mafs don't always set codes but due to them going bad will upset sensors further along the system causing them to set codes when they detect something is not right. Smoke test the whole vacuum system to make sure there are no leaks, try cleaning the Maf with Maf cleaning spray, Bad Maf I had couldn't be revived with cleaning, new OEM part solved my issue.
Worst air leak I found was on a 2.2 Z3 tracked that down to the plastic cam/rocker cover developing cracks around No 4 Plug well, caused overfueling fuel trims high as it tried to compensate for the extra air the exhaust was seeing not having passed through the Maf and being measured.
Your Battery voltages look good to me, think you can rule that out.
Just because a code for a certain componant is set dosn't always mean thats where the problem is, it might be something further up or down the system thats causing it to set.
Don't see the instrument pod being the issue either.

 

[colb]

If any of the previous ideas don't solve the problem have a look here https://autoservicecosts.com/obd2-codes/p1515/
Maybe the wiring to throttle body is bad as suggested in the link as to possible causes of P1515

 

[ph001]

Well it does look like the sensor is inside the throttle body itself so nothing external. I’m thinking connector or wiring. Could either be the throttle body end or the accelerator pedal end.

 

[Smartbear]

Well it does look like the sensor is inside the throttle body itself so nothing external. I’m thinking connector or wiring. Could either be the throttle body end or the accelerator pedal end.

On a previous car i owned, a similar problem was caused by dirty tracks inside the throttle body cover (it’s the actuator motor i believe)
Similar to the z4 wiper motor issue, the problem disappeared when the tracks were cleaned of carbon/grease residue
Rob

 

[ph001]

I think OP has replaced the entire throttle body though. Assuming he bought oem new and hasn’t fitted a faulty part!

 

[Stevepj]

The 2774 code relates to a CAN engine cut off time fault and has been known to be linked to fuel pump failure, which may be worth investigating.
Most Internet searches list P1515 as being related to the throttle position in one way or another, but the one I've linked below also points to a CAN fault and engine time plausibility issues.

https://www.autocodes.com/p1515_bmw.html

The Z4 use the dashboard as the meeting point for all the systems which could be why the dash was identified earlier if it wasn't receiving all the right inputs.

I had an example of how hard to trace these faults are with my son's Focus ST a few weeks ago. The car was throwing all sorts of codes relating to emissions, fuel pressure, CAN US, active suspension, traction control and more I can't remember. It would keep going into limp, the engine service light and EML were lit, auto stop start wouldn't operate and the hatchback would randomly unlock.
Ford couldn't identify the problem and their best advice was to clear the codes, drive it for a week and bring it back to check for any faults.
We kept looking and eventually found the cause of all these issues. The car had been in for a recall on a clip holding the fuel pressure sensor in place and whoever replaced the clip also fitted a cable tie around the sensors wiring plug. The cable tie cut through the insulation on two of the wire and they were intermittently shorting together and causing havoc in the CANBUS signal. Removed the cable tie, separated the wires and everything returned to normal.

 

[SystemLord0]

Thanks for all the pointers guys!

For a quick review:
- Throttle body has been changed to a new one so that is out of the equation
- Idle Air control valve i removed and cleaned and the little flaps moves and moved freely.
- Accelerator pedal had been replaced for testing and didn't resolve the issue
- Battery seems fine; is new and the P1515 issue has been around for a long time now and getting worse over the years. Does not seem to travel with the battery and alternator seems to be fine.

I went over your comments and came up with the following action plan to continue:

1) New DISA valve is coming in tomorrow and i will replace it (already payed for it) so this would eliminate the DISA valve.
2) I will inspect the MAF sensor and clean it with MAF cleaner...maybe its been building a deposit on it even thou everything in the air system seems somewhat clean. MAF: Measure Ohm/Voltage; Clean; Measure and compare. Then test the whole system to see if that fixes anything.
3) If the DISA and MAF wont give me results i will have to start looking closer into the connectors and their wiring. I will start with the throttle body and accelerator pedal connectors and wiring. Does anyone have or know a source where i can get wiring diagrams? This way i could check my wires from source to source and make sure they are not intermittent etc.
4) If i cant get anywhere with the wiring i will try to get a smoke check done to check for any leaks in the intake system. I don't have a smoke making apparatus so i would have to get one so this is why i have moved this further down the line.


My OBDII can read live data; i will check on what it can read but i am sure i saw options for:
Mass Air Flow Rate lb/min (Can i use this to check my MAF sensor to compare to values someone else is getting?)
Absolute Throttle Position
Fuel Trim Bank 2 and 1 (Long and Short Term)

I am not sure what i would be looking for thou.

Will be a busy weekend; ill report back on each steps to see if we learn anything new.

Thanks again!

 

[SystemLord0]

I did not by the BMW OEM throttle body; i bought the VDO replacement. It had decent reviews and was a bit cheaper at 250 vs 500 from BMW.
https://www.fcpeuro.com/products/bmw-throttle-body-oem-13547502445#qa
Should i try OEM instead?

Other than than the fact that i use Chevron gas (sometimes Shell) and have used fuel and ejector cleaner (maybe once year) i have no info on the fuel pump. Engine seems to be getting gas and does not seem to be sputtering etc but i will look up if there is a way to some info from the pump. Full pressure gauge at the engine etc.

That being sad one the only other code is that 2774 (Engine cut off time) so maybe that does have something to do with it. For now ill try my stems from above and see where we end up before heading to the pump.

 

[SystemLord0]

Hi everyone; thanks for sticking around and helping me get my car going again.

I have a few important updates;
I started looking into the live data from my OBDII reader and started mapping RPM (PID 01 0C); Mass Air Flow (PID 01 10) & Absolute throttle position (PID: 01 11 ). From the get go i noticed that the throttle position info did not always perfectly follow my pedal movements but its hard to notice when looking at the hand held reader so i exported the data to excel. I was expecting the RPM, MAF and ATP to be behaving very similarly; press on gas = increase airflow = rpm increase.
However it seems like the ATP has some readings that are not consistent with the engine behavior nor gas pedal moment. The engine behaves as it should based on my foot moment but the ATP reading does not match.
I have attached a PDF (with notes) and my source data with graph in excel. The excel graph is nice too look at but PDF does how it too.
I was not sure if the ATP reading is just not perfect from the OBDII so i did the same data output on my brothers 2005 Subaru and his behaved exactly as expected with all three values moving together and the ATP registering also slight foot moments.

I think this is good evidence to support that the P1515 is related to the throttle system somehow and this area is worth looking into in more detailed. For some reason this Absolute Throttle Position % is not consistent with what is commanded via the foot pedal. I think the location where the ATP% (PID 01 11) is measured or calculated from is the source of the error and P code.

The gas pedal seems to be sending the correct position to the car since the physical response from the car feels "right" and the MAF rate and RPM seems to be responding consistent. However whatever measured the ATP or values used to calculate the ATP are incorrect.

I am not sure if the gas pedal uses a poti of some sorts to output position because i could read these values to confirm its working correctly. If its digital it would be harder.....

-I changed the TB already so that seems to be unlikely bad again.
-The DISA valve was changed today; there where some slight defects on the flap seals and i was hoping replacing it would solve my issues but it seems to not be the primary cause at least.
-MAF sensor was cleaned to day (with MAF cleaner) and it looked in good shape and it seems to be reading mass air flow correctly based on RPM increase. But i have not measured it yet (Ohm, voltage etc).

Hopefully this information will be helpful to figure out what to look at next / possible causes.
Could it be that the computer that's calculating the ATP is faulty? Where is that done?

PS: I noticed i cant upload EXCEL or PDF files.... i uploaded JPGs of the graphs for now but i will see if i can figure out how to upload files online somewhere and share the URL or i can PM the files if needed.

Manuel