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Discussion Starter #1
Ok I have searched enough and no simple fix seems logical for my car. New Thread Time. First off Problems, then car history

Purchased car 2 months ago and on the drive back the SES triggered. When I bought the car the previous owner informed me that the car took a while to warm up, minute or so. The car was given a PPI and only thing found was a potential gasket leak for trans fluid that would need to be adressed at a later date. I had never owned a big V8 before and thought that these engines could just need to warm up to operate correctly.

Rough Idle on Cold Start (left off 5 or more hours):
Engine revs to ~1200rpm then slowly settles to 700ish. Car is un-driveable if not left to warm up for a minute (redline moves slightly higher, 2bars). The throttle is almost completely un-responsive, feels like drive disengages or no gas is getting to engine.
Pulled codes:
(CE) Misfire During Warmup, Cyl #2
(CF) Misfire During Warmup, Cyl #3
(D1) Misfire During Warmup, Cyl #5
(D2) Misfire During Warmup, Cyl #6
(A3) Control Unit Self-Test, master reset
(D5) Misfire During Warmup multiple Cylinders
(B2) Catalyst System Efficiency Bank 1
(B3) Catalyst System Efficiency Bank 2
(AE) Air Fuel Adaptation Bank 1
(AF) Air Fuel Adaptation Bank 2

Month ago engine revs to 1200 then stalls for first 2 cold starts. On 3rd it starts just as described above. I cleared the SES and pulled:
(B2) Catalyst System Efficiency Bank 1
(B3) Catalyst System Efficiency Bank 2
(AE) Air Fuel Adaptation Bank 1
(AF) Air Fuel Adaptation Bank 2

Currently the engine revs up to 1200 then drops immediately to 1000, no stalling, then slowly down to what appears to be 400 on the cluster gauge (i was panicking). The diagnostic menu, though, says 600-620rpm which to me is still low. I took it to a Foreign Auto Shop and they vacuum tested the car, no leaks, and drove it, saying it seemed fine. This was not after a cold start.
Next, I took it to a BMW dealer, they told me it didn't start up weird after sitting out in the cold all night. I have no idea what they looked at because it does the same thing consistently every morning. They recommended stock filters for my K&Ns. Replaced, no effect.

Just pulled codes again and got the same 4 above plus 69 (coolant temp plausibility). I ran the KTEMP test and got 80-84 after driving city for 10 minutes, Started around 49. I also did the MAF test and pulled 126 L/H. I plan to do the IATS relocation this weekend.

I bought the car (2000 m5) as the 4th owner with 49000 miles and all service records. All quick fixes were replaced on the car within the last 2 years and about 6000 miles, So i am at a loss of where to to go now. Services as follows:
NGK Spark Plugs (Nov '09)
Thermostat (Feb '10)
Coolant Temp Sensor (Feb '10)
2 x O2, post and pre cat (May '10)
Fuel Filter (May '10)
Bosch MAF (May '10)
2 x CPS, outlet inlet (May '10)

I have searched for these symptoms for about a month now and most of the advice says to replace the above sensors as a start to troubleshooting the problem. I wouldnt't think any of these have gone bad yet. Any Advice or direction? Sorry for the length
 

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B2 and B3 are in the Peake knowledgebase sticky. If not CPS then vanos solenoids need refreshing.
PS - there are 4 CPS (2 banks, inlet & outlet), and 4 O2 (pre and post cat, 2 cats).
 

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Maybe your aftermarket K&N Filters oiled up the newly replaced MAF's? However, I doubt that faulty maf's would cause all of your issues.
 

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B2 and B3 are in the Peake knowledgebase sticky. If not CPS then vanos solenoids need refreshing.
PS - there are 4 CPS (2 banks, inlet & outlet), and 4 O2 (pre and post cat, 2 cats).

I don't think that a B2/B3 cat efficiency is caused by a cps or vanos solenoid. At least not in my experience of having multiple failures of each of these.

I would be looking at the MAF's and pre/post-cat O2 sensors first.
 

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69 is in the Peake sticky too, and is generally indicative of a thermostat. What was the ambient temperature when you did the KTMP reading? A cold day (<60F) will better expose a faulty thermostat.

That said, I would be surprised to find that those 2010 parts have failed already. Also, ~600rpm idle sounds reasonable to me.

The other thing you can check is whether you have cracks in the welds where the O2 sensors connect to the exhaust. The vanos solenoid is the hardest of the aforementioned fixes; consider that last.
 

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x2 on the K&N filters (if the oiled variety) possibly wrecking those new MAFs. And since you're in Ohio and it's October you can easily test your thermostat. Just take her out on the highway at night (under 55F ambient ideally) and be sure she holds 79C. If not you know what to do.
In the meantime run to an autoparts store and buy some new paper filters as a start. Throw those "upgrades" in the trash. Maybe you get lucky and you can just clean those MAFs. Mixed results on that though iirc.
 

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Discussion Starter #7
Chowdah I am aware that these codes were posted in the Peake sticky. I searched through it and all of the quick fixes regarding these problems seem to relate to sensors that are new on my car.

I guess my notation was confusing. I meant 2 each of the inlet and outlet CPS, same for O2s.

I have cleaned the MAFs myself and had them cleaned professionally. Before and after cleaning, i noticed no difference. Also, car operates the same with and without MAFs plugged in.

I ran the KTEMP test on my way to work this morning at 52 F and the diagnostic read between 72-75, steadily increasing. I am pretty sure that the KTEMP sensor is designed to read 79C as sort of its zero point, min value, so do my readings above and as explained earlier (starting at 45 and increasing to low 80s) indicate a bad sensor?

Thanks for the help guys
 

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The tstat/ktmp is never supposed to read lower than ~79degC when the car is warmed up. If I presume your commute in ~50degF ambient temps to be enough driving to warm up the engine, then I'd guess you are in for a new tstat.

However, a tstat wouldn't seem to relate well to your startup symptoms, above. Does your idle hunt ever on startup? If you trust your O2 sensors (and MAFS especially given posts #3/4/6), then you might want to look for an intake leak (hose/gasket/o-ring). As rubber heats and expands, the problem would diminish.
 

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dont always assume its electrical...not to sure on the breather set up on these but i have come across a fault on the 3.5/4.0ls v8 ,i found the manifold breathers to be failing..it runs through the sentre of the plenom chamber and has a large diaphram on the bulkhead end that splits and alows vacume to escape,it will cause the engine to run rough ..but not always,check your plugs for coulour of burn,should be light brown...if oily ..check breathers as it can push oil in to the inlet(may also pink) at certain revs....its normally the back plugs that get oily.
 

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Discussion Starter #10
Chowdah,
When I went to lunch this afternoon my idle was hunting pretty good (30 seconds or so) revving between 900 and 1100 RPM. I was under the impression that the KTEMP diagnostic reads the coolant temperature sensor, the one front and below the air intake on the passenger side. How do you diagnose a faulty tstat. Do I have my facts straight here? Does the KTEMP diagnostic contain a combined signal from the coolant temp sensor and the tstat? The problem I am having is judging how to determine whether or not the car is warmed up. Would you consider it warmed up when the idle moves from 4000 to 4500, or when it moves all the way up to 6500. If I drove it around for a while I have no doubt that my KTEMP would climb to the low 80s in 50F temperatures. i will have to wait a little while til the temp drops again to do this test over.

Thanks,
 

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You could say the engine is warm when the tach lights back off. If your KTMP indeed reads above 80C in 50F ambient, then get on the highway, cruise a few miles, and see if the temp drops under ~79C. If it does, then you probably need another new tstat. The key to this test is cold ambient temps.

There are two temperature sensors at play. #11 here and #21 here.

Independent of the tstat result, your hunting idle is probably something else (e.g. MAFS,leaks). Next time it cold-hunts, pop the hood and tap on the airboxes and tubing to see if you can aggravate it.
 

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Discussion Starter #12
Chowdah,

If it is a Temp problem what makes you think it would be the #11 Double Temperature switch and not the #8 Thermostat.

I will try tapping on the intake hoses and airboxes next time I cold start it. I had the car smoke tested for leaks, but another moderator here told me not to trust that as the end all be all test for leaks. How do you feel about this? The BMW dealer said next they would want to pursue checking the exhaust manifold. Do you think anything could be awry here?

Thanks
 

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I ran the KTEMP test on my way to work this morning at 52 F and the diagnostic read between 72-75, steadily increasing.
You need a thermostat. Unless...

The way to properly do the test is to get the car up to 79C. Stop and go traffic will do it. THEN take it out on the highway so the radiator is exposed to that cool wind. Did you see 79C before your 'hi speed' run?

The phrase 'steadily increasing' is throwing me off. Makes me think you weren't up to temps yet before you hit the highway. If not get to 79C first...then hit the open road.
 

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Discussion Starter #14
TM,

To clarify, I did the KTEMP test while driving to work this morning at 52F outside temperature. I started the test about 3 miles into my 6 mile city drive (not stop and go per say). The car felt warmed up and responsive, redline at 6500, when i started the test and the KTEMP reading was around 70. It quickly jumped to 72 and increase to 75 about 1 degree every half mile or so, til i pulled into work with it at 78C. I will have to run the test again when the weather gets colder, maybe one of these nights and I will hop on the highway.

I am a little confused about the 79C baseline for these sensors. To me it seems illogical that 79 would be the, say, calibration point for the sensor, below which all readings indicate a bad sensor when the car is warmed up. What exactly defines a car to be warmed up and how do we know what the sensors range of accurate readings is?

Thanks again for the help guys.
 

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You should consult the thermostat links in the DIY sticky, to understand the mechanism. I am not implying that #11 or #21 are at fault.

From personal experience, I can tell you that after the dealer replaced my MAFS, I had a hunting idle and occasional stall. It turned out that they pinched an o-ring in the intake when installing it. Tapping on the intakes exposed the problem.
 

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dont always assume its electrical...not to sure on the breather set up on these but i have come across a fault on the 3.5/4.0ls v8 ,i found the manifold breathers to be failing..it runs through the sentre of the plenom chamber and has a large diaphram on the bulkhead end that splits and alows vacume to escape,it will cause the engine to run rough ..but not always,check your plugs for coulour of burn,should be light brown...if oily ..check breathers as it can push oil in to the inlet(may also pink) at certain revs....its normally the back plugs that get oily.

Not the setup on the S62, that is the M62 setup. Ours are simpler in design.
 

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I am sick of losing my reply to that maintenance window!!!!!!! Fix the site please!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Or shut it down till fixed.
Sorry OP for unrelated rant.

So you have 4 new cps and 4 new O2 sensors, correct? You have cleaned the MAFS but have you simply unplugged them and seen how it runs with them unplugged? Do that will not hurt the car but how you describe the differences will tell a lot.
The temp sensor is designed to read the temp it is in, there is only the reading of what it is in no matter what that temp is. It will read from -128c right up until the engine seizes. There is no other design in the sensor.
Compare ktemp to the oeltemp in test 16 and report what you see during start up and driving. Also when you first get in the car cold the ktemp should be the same as outside air temp and the same as oeltemp, check that, also Atemp which is test 7 left button pushed twice after ktemp. All the same +-a degree or two.
The car should take 5 min to get to 78 then hang as the T-stat opens as cool coolant enters after 12 min it should be a solid 79-80. That is with normal driving. If the temp is low it is the t-stat not closing, not the sensor. Sensor being bad has different symptoms than you are understanding.

Did the dealer do a vanos test on GT1?

Your fuel codes are likely related to your B2,3. The one we don't have a lot info on is the A3. By any chance do you the Pcodes it helps for the fuel codes? Strong chance of air leaks, unplugging the MAFs will help decide.
 

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Discussion Starter #18
You should consult the thermostat links in the DIY sticky, to understand the mechanism. I am not implying that #11 or #21 are at fault.

From personal experience, I can tell you that after the dealer replaced my MAFS, I had a hunting idle and occasional stall. It turned out that they pinched an o-ring in the intake when installing it. Tapping on the intakes exposed the problem.
Got it! I thought you were referring specifically to two of the sensors that you suspected were wrong. I am slightly familiar with the functionality of the thermostat from a DIY on the thermostat housing removal and maintenance. I am not too familiar on the coolant temp. I will search. Do you know of a good writeup off hand that explains the how the coolant temp and all the components of the tstat housing interact to read out the KTEMP?

Which o-rings specifically are you referring to? Now that you mention it, one of my o-rings, large one, on the inside of the intake tube to the MAF housing was flattened in a half inch section. It looked as if it had been heated very high and flattened with someones thumb. I thought maybe it was part of the o-ring design because it was so symmetrical. This intake tap; do you tap the tubes, making them bow up and down to open up the seal between intake tubes? Does this then exagerate the leak, causing a more significant leak?

Thanks for your input
 

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Discussion Starter #19
I am sick of losing my reply to that maintenance window!!!!!!! Fix the site please!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Or shut it down till fixed.
Sorry OP for unrelated rant.

So you have 4 new cps and 4 new O2 sensors, correct? You have cleaned the MAFS but have you simply unplugged them and seen how it runs with them unplugged? Do that will not hurt the car but how you describe the differences will tell a lot.
The temp sensor is designed to read the temp it is in, there is only the reading of what it is in no matter what that temp is. It will read from -128c right up until the engine seizes. There is no other design in the sensor.
Compare ktemp to the oeltemp in test 16 and report what you see during start up and driving. Also when you first get in the car cold the ktemp should be the same as outside air temp and the same as oeltemp, check that, also Atemp which is test 7 left button pushed twice after ktemp. All the same +-a degree or two.
The car should take 5 min to get to 78 then hang as the T-stat opens as cool coolant enters after 12 min it should be a solid 79-80. That is with normal driving. If the temp is low it is the t-stat not closing, not the sensor. Sensor being bad has different symptoms than you are understanding.

Did the dealer do a vanos test on GT1?

Your fuel codes are likely related to your B2,3. The one we don't have a lot info on is the A3. By any chance do you the Pcodes it helps for the fuel codes? Strong chance of air leaks, unplugging the MAFs will help decide.
4 new CPS and 4 new O2s (as of about a year ago, self install by previous owner). I have cleaned MAFs. I unplugged the MAFs and the car started up the same, hunting idle cold, and running what i think is a little sluggish in first gear (didnt mention that above). So no difference with MAFs unplugged or plugged in.

I have to do some highway driving tomorrow so i will note the KTEMP, Ambient, and OELTEMP at startup, after 5 mins, and after 15 mins or so on highway. I really think this will help diagnose the problem. Thank you soooo much for that description of the tstat functionality. That helped a ton. I also thought that the temp sensor read around a baseline calibrated value. I didn't think this made any sense, and im glad to hear that it is just a simple reading.

No my dealer does not have a GT1. I have no respect for my local BMW shop and will not be giving them business unless i have to. They ignored me when i was looking for cars, and paid little attention to my cars symptoms when i had it in.

By PCodes i assume you mean the 4digit codes? My car is a 2000 and as i understand it only gives the 2 digit codes from Peake table 1b/18. I think the A3 code was sort of a fluke. I havent pulled it since. If i get to it this weekend I want to relocate my IATS and check the plenum and intake for leaks.

Glad to have you on board this thread Sailor24. I have seen you provide a lot of help in diagnosing similar problems to mine and appreciate the help!
 
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