[iaknown]

OK guys, still getting the above code and could use some help. And this is where diagnosing BMW's gets tricky. The OBD code P02CA designates Turbocharger/Supercharger B Overboost Condition" however the BMW specific code references "low pressure stage control". I broke out the DIS/GT1 on the car today and it points me to a comparison between the MAF air temperature and the intercooler to throttle pipe (intake) temperature sensor (my code is for a deviation). Was scratching my head trying to understand why. Apparently the air temperature is used to help determine volume which in turn has a bearing on the dde's boost control. It says the MAF temperature should be hotter than ambient and the intake pipe temperature should be even hotter than MAF which all makes sense. My intake pipe temp was lower than the MAF so I pulled the sensor and found a bunch of oil on it. Sprayed it off and it got a lot better, now its about the same as MAF (which still doesn't seem right).

So, all that being said......Would somebody mind comparing their MAF temperature to the intake tube sensor temperature at an idle and let me know what they come up with? That should let me know if I have a bad sensor. This probably can't be done in Torque, I don't see the MAF temp there, but possibly in BMWhat or something else BMW specific.

[temporaptor]

I looked up the BMW code 428B online and it's says " boost pressure control of Large tubo control Deviation". Maybe the tune is having trouble controlling over boost with no DPF. When my DPF clogged I threw the bmw code of 428A "boost pressure control of Large tubo control Deviation" I assume mine was under boost.
I'll check my car at idle when I get a chance with bmwhat.

[TDIwyse]

Originally Posted by iaknown

OK guys, still getting the above code and could use some help. And this is where diagnosing BMW's gets tricky. The OBD code P02CA designates Turbocharger/Supercharger B Overboost Condition" however the BMW specific code references "low pressure stage control". I broke out the DIS/GT1 on the car today and it points me to a comparison between the MAF air temperature and the intercooler to throttle pipe (intake) temperature sensor (my code is for a deviation). Was scratching my head trying to understand why. Apparently the air temperature is used to help determine volume which in turn has a bearing on the dde's boost control. It says the MAF temperature should be hotter than ambient and the intake pipe temperature should be even hotter than MAF which all makes sense. My intake pipe temp was lower than the MAF so I pulled the sensor and found a bunch of oil on it. Sprayed it off and it got a lot better, now its about the same as MAF (which still doesn't seem right).

So, all that being said......Would somebody mind comparing their MAF temperature to the intake tube sensor temperature at an idle and let me know what they come up with? That should let me know if I have a bad sensor. This probably can't be done in Torque, I don't see the MAF temp there, but possibly in BMWhat.

In Torque the Intake Air Temp is apparently from the MAF. There's also an Ambient Temp which I think is the sensor up by the cowl... I haven't been able to find the temp sensor on the charge pipe in Torque ... But with the Bav Tech it can see the temp sensor on the charge pipe (verified by unplugging it and plugging it back in... I haven't looked for that in BMWhat.

Are you using H2O/methanol injection? If you're injecting it pre IAT sensor before significant boost is happening then you may be causing the IAT to see significantly lower IAT's due to its cooling impact.

[iaknown]

Originally Posted by temporaptor

I looked up the BMW code 428B online and it's says " boost pressure control of Large tubo control Deviation". Maybe the tune is having trouble controlling over boost with no DPF. When my DPF clogged I threw the bmw code of 428A "boost pressure control of Large tubo control Deviation" I assume mine was under boost.
I'll check my car at idle when I get a chance with bmwhat.

Yes it all comes into play for the boost pressure control, but that system is pretty complicated. I remember reading exhaust back pressure is monitored as well and has a bearing on the boost.

Thanks for the info.

[iaknown]

Originally Posted by TDIwyse

In Torque the Intake Air Temp is apparently from the MAF. There's also an Ambient Temp which I think is the sensor up by the cowl... I haven't been able to find the temp sensor on the charge pipe in Torque ... But with the Bav Tech it can see the temp sensor on the charge pipe (verified by unplugging it and plugging it back in... I haven't looked for that in BMWhat.

Are you using H2O/methanol injection? If you're injecting it pre IAT sensor before significant boost is happening then you may be causing the IAT to see significantly lower IAT's due to its cooling impact.

Hmmm, I remember seeing 2 more air temps in BMWhat. Forget what they were called. Are you able to compare the 2 with BavTech?

No, I am not injecting yet. Want to get the car running right before I start playing with it.

[TDIwyse]

Originally Posted by iaknown

Hmmm, I remember seeing 2 more air temps in BMWhat. Forget what they were called. Are you able to compare the 2 with BavTech?

No, I am not injecting yet. Want to get the car running right before I start playing with it.

FYI, I'm on my 2nd IAT sensor. First one went bad around ~20k miles. Although it started reading significantly higher temps than actual. I verified that by pulling the IAT sensor from the intake charge pipe and having it in the ambient air... And everytime I've looked at mine it's also covered in an oil film from the crankcase fumes.

I may have some old data logs with this info in them when diagnosing the above problem. I'll take a look. Worst case I'll have to break out the Bav Tech tool again, which would mean closer to the weekend before getting data back to you...

[iaknown]

Originally Posted by TDIwyse

FYI, I'm on my 2nd IAT sensor. First one went bad around ~20k miles. Although it started reading significantly higher temps than actual. I verified that by pulling the IAT sensor from the intake charge pipe and having it in the ambient air... And everytime I've looked at mine it's also covered in an oil film from the crankcase fumes.

I may have some old data logs with this info in them when diagnosing the above problem. I'll take a look. Worst case I'll have to break out the Bav Tech tool again, which would mean closer to the weekend before getting data back to you...

Thanks. I have a new one on the way but want to see what others are showing before I throw parts at it.

[TDIwyse]

Originally Posted by TDIwyse

...
I may have some old data logs with this info in them when diagnosing the above problem. I'll take a look. Worst case I'll have to break out the Bav Tech tool again, which would mean closer to the weekend before getting data back to you...

This may be helpful.

http://www.bimmerfest.com/forums/sho...1&postcount=62

This is comparing IAT's at the temp sensor on the charge pipe after the intercooler for a full fueling run with 30/70 H2O/meth... The beginning temp before the spray starts would be an example of the IAT measured at coasting before the run starts. The ambient temps are listed on the top of the charts. So for the 90F run the IAT was measuring ~96F before the fuel/boost started. For the 98F test the IAT was measuring ~106F before the fuel/boost started.

And attached is a recent Torque screen shot comparison for the "Air Temp" the car is measuring and the "Intake Temp" for a steady state cruise. The Intake Temp is from the MAF. Even without air scoops at the grill you can see it's basically ambient ;-)

[iaknown]

Originally Posted by TDIwyse

This may be helpful.

http://www.bimmerfest.com/forums/sho...1&postcount=62

This is comparing IAT's at the temp sensor on the charge pipe after the intercooler for a full fueling run with 30/70 H2O/meth... The beginning temp before the spray starts would be an example of the IAT measured at coasting before the run starts. The ambient temps are listed on the top of the charts. So for the 90F run the IAT was measuring ~96F before the fuel/boost started. For the 98F test the IAT was measuring ~106F before the fuel/boost started.

And attached is a recent Torque screen shot comparison for the "Air Temp" the car is measuring and the "Intake Temp" for a steady state cruise. The Intake Temp is from the MAF. Even without air scoops at the grill you can see it's basically ambient ;-)

Great, thanks. Something seems up because there is no way the air can pass through a turbo and a bunch of hot piping and stay the same temp. Whether this is the cause of my CEL who knows, but we'll see. It's killing me though cuz I have stuff on the way

[Yozh]

I'll try to check it out tonight.

[iaknown]

Thanks. If you're using BMWhat it looks like you want Ambient Temp (self-explanatory), Air Temp at the HFM (should be MAF temp) and Charge Air Temperature After Charge Air Cooler and/or Temperature Upstream of Intake Manifold

[Yozh]

So, here is what I got from BMWhat and Torque. This is on car that has been sitting for good 4 hours and in these scenarios engine is not running and has not been started. But this should give you the difference in sensors. BMWhat can see both a MAF air temp (P1=Air Temperature Before Compressor) and intake charge air temperature (P5=Charge Air Temperature After Charge Air Cooler). All other ones I have set in there to see what else is there:



And in Torque I could only see the Intake Air Temperature and this looks like the one after the intercooler:



And here is an overlapping list of Torque available sensors:

[Yozh]

iaknown, please let me know if you want any of these ran during normal driving or full fuelling. Although, I seem to have a hard time finding a good empty "test track" for my full fuelling runs.

[TDIwyse]

Originally Posted by Yozh

And in Torque I could only see the Intake Air Temperature and this looks like the one after the intercooler

That's interesting. When I was looking at Intake Air Temp in Torque I could disconnect the IAT sensor and it had no impact on this reading, but on the Bav Tech the IAT reading pegged. That caused me to think Torque wasn't reading the sensor in the charge pipe.

[iaknown]

Originally Posted by Yozh

iaknown, please let me know if you want any of these ran during normal driving or full fuelling. Although, I have a hard time finding a good empty "test track" for my full fuelling runs.

Thanks Yozh but I believe air temperature before the compressor may have something to do with the AC. I noticed an instant change depending on whether the AC is turned on or off. I need to see the temperature of HFM that I referred to in my previous post.

If you could do this on a hot car that would be ideal.

[Yozh]

Here you go. This is a 30min very relaxed drive to work mainly through the city at 30-40mph and only in the last 5min I hit a bit of a why at 60-70mph. Last 4 min had A/C on then I turned it off and then idled for 2-3min. Graph has only 2 parameters that you are interested in graphed. In the data you can see that I took all 6. Based on time stamps you can see that I did screenshots of the start and the end before the shutdown. If you want the whole data file, shoot me a pm with your email and I shall email it to you.

PS: Air temp at the HFM seems to go to negative values when engine is off.

[iaknown]

Originally Posted by Yozh

Here you go. This is a 30min very relaxed drive to work mainly through the city at 30-40mph and only in the last 5min I hit a bit of a why at 60-70mph. Last 4 min had A/C on then I turned it off and then idled for 2-3min. Graph has only 2 parameters that you are interested in graphed. In the data you can see that I took all 6. Based on time stamps you can see that I did screenshots of the start and the end before the shutdown. If you want the whole data file, shoot me a pm with your email and I shall email it to you.

PS: Air temp at the HFM seems to go to negative values when engine is off.

Attachment 1082964

Attachment 1082965

Attachment 1082966

Perfect, thanks. So I definitely got something wrong because your post-intercooler temps are quite a bit higher than the MAF (as expected). I really hope this sensor solves the issue....

[Yozh]

I suppose another way to do it is to measure the voltage/resistance at the temp sensor in question. But looks like you got one on the way, hope it works.

[iaknown]

Still trying to sort this out... Next question for you guys: What is the max boost you are seeing?

[TDIwyse]

Took some data this weekend that might be helpful. In the Bav Tech tool there's data on the Boost Pressure Actuator (BPA) as well as the "desired" boost the car wants and the "actual" boost it's measuring. I've posted the Desired/Actual before, but this time I captured it along with the BPA behavior.

This for a 3rd gear full skinny pedal pull on a ~68F day with low humidity. Not sure if this is something that's useful to you, but I hadn't seen someone post the BPA behavior for this kind of situation.

[GottaBeKD]

That is the first time I see desired vs actual boost graphed. Thanks for this TDI.

I am assuming you have the stock intake. If so it is doing a good job keeping up with demand.

[Puerto Rican 335d]

ok amigos i will be joining your techie world in a few days, my Elm237 Super Mini is on its way to the Island