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Discussion Starter #1
I've been reading this forum for a while and getting tips on repairing my 2006 325i with N52 engine and automatic that I bought from a dealer who couldn't get it running. Apparently it was jumped in reverse polarity. Was completely dead when I got it- wouldn't react to start button at all. I've replaced the battery with a white BMW 720amp; new IBS, checked all junction box fuses and engine control fuses (all are good); replaced the brake light switch; replaced starter; and replaced fuel pump as I progressively got power to each and diagnosed each as being faulty. Replaced spark plugs after fuel pump- it fired up and ran at idle for a few minutes on the old plugs on the first try after new fuel pump, but got fouled from oil I had placed in cylinders to lube them- car had sat for several years without starting. Naturally, I've changed the oil and filter prior to starting repairs. Ground strap from the engine/ coil wiring to right shock tower is good.

Engine now turns, gets fuel, occasionally will reluctantly start and fumble along at idle, then die. I have spark on #1 cylinder, less spark on #2 and cylinders 3-6 have very little to none- plugs are wet, but not showing signs of combustion. I've moved the coils from #1 and 2 to other cylinders and spark does not follow those coils.

I have very few codes from the engine module, despite the lack of spark and poor running. All I get from the engine module/ DME with my Bavarian Tech tool is CDA8- status Kombi, 1B4 (I believe this relates to the instrument cluster. The BC computer stalk does not function yet.) and CD94- outside temp/ relative time, 310. I replaced the temp sensor that mounts above the DME in the cabin filter tray and the correct outside temp is displayed on the instrument cluster, though.

What tests can I do to determine whether the DME is damaged? Why is it not outputting codes relating to ignition troubles? Is that portion damaged to the extent that it doesn't communicate? What is process for diagnosing lack of spark on this one? Thanks for your help!
 

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Maybe try the crank sensor
 

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Discussion Starter #3
I haven't tested or replaced the crank sensor. Hadn't seen any codes pertaining to it. Will it throw a code if it's bad? Is there a way to check it with the Bavarian Tech tool?

I removed the Vanos solenoids and they're clean.

I did get an occasional "cam sensor not synchronized" code on both intake and exhaust cam sensors. I saw a post where that code was thrown on a car with the timing out of adjustment.

I checked voltage at the intake and exhaust cam sensors and had 5v, 0v and .3v on the 3 wires on each sensor. Should the 3rd wire have 12v battery voltage? If so, I'm not getting correct voltage to the sensors. Where is the voltage supplied to the cam sensor- from the DME or the interior fuse panel? All fuses are good. My BT tool shows a value of 0 on the cam sensors when cranking. I haven't seen it change to 5 and back to 0 as it's supposed to. I assume this value is being read from the DME by the BT tool. Is that correct?
 

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You may be able to check to see if you get any RPM reading with the BavTech tool but not sure.

I missed the part where you are getting some spark.

You may want to diagnose the VVT motor and make sure it is operating correctly. That can cause incorrect air/fuel mixtures and cause poor engine performance or none at all.

Also, I doubt any sensor is getting 12v. Typically sensors only operate on 3.3v or 5v
 

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Discussion Starter #5
Finally had some time to analyze the E90 again with my Bavarian Tech tool. It appears that the DME is controlling spark and fuel injection duration- they vary a bit while cranking and values are output by the DME.

Typical spark duration was 2.05 ms. The range was between 1.02 and 3.07 ms. Is that a normal range?

Fuel injection duration was 15.41- 15.70 ms.

I got a 2A9A camshaft sensor inlet, signal error- short circuit or signal interruption. And 2A9F camshaft sensor outlet, synchronization- short circuit or signal interruption.

So, I watched the camshaft sensors as I cranked the engine and found that each would switch between 0.00 and 0.38v as the engine cranked. .38v is the voltage I measured on the signal wire to each sensor. So it seems that the sensors are detecting the cam position and sending the low voltage signal to the DME and the DME outputs that to the BT tool. Not sure why it would indicate an error- any ideas?

While cranking it I got a nominal value inlet camshaft inclination of 121.60 degrees CRK and actual of 120.00. Actual outlet value was -115.00 degrees. Further down the menu on the BT I saw other camshaft position measures, so I cranked it and saw 127.12 camshaft inlet nominal value with camshaft inlet at 125.62; outlet was -115.00 and nominal outlet value was -115.37. Are those appropriate numbers?

I checked the normspreizung (translated "normal spread") outlet and inlet numbers and don't know what to make of them. The outlet was 1,424.8 degrees CRK and inlet was 84.80 degrees CRK.

Here are measurements for the VVT: eccentric actual value 45.81; eccentric nominal value 45.99; status byte VVT-output ATIC 61= 255.00; status VVT discharge relais 2.00; VVT actual angel 45.31 degrees; nominal angel 25.78%; VVT engine current 0.00A; VVT sensor power supply 4.90v; VVT sensor difference 0.00 degrees; VVT decharging relay on 1.00.

I don't know how to interpret all this data to see if it points to the cause of my no start condition. It acts like it wants to start as I crank it- gets ignition on some, but not all cylinders, or not in correct time. I appreciate all your help! Looking forward to solving this puzzle.
 

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Discussion Starter #6
So to follow up on my thread- I sent the DME to SIA Electronics in Illinois and they determined that it was damaged beyond repair. I expected that they'd charge me their $220 repair fee for diagnosing it, which I think is very reasonable, but they didn't charge me anything for testing it. I would have been perfectly happy to pay their fee to just know definitively that the DME was the source of the problem. I did pay for return shipping, $13, so I could use it for a core if I bought from a dealer.

I ended up buying a salvage yard DME off eBay, though, and plan to send it out to be programmed. Not only was the eBay DME the same model code, but it's the same programming code and just a few hundred vin numbers apart from my car. Only paid $111 shipped for it.

Do any of you have recommendations for places that program DMEs? I'm planning on sending it to rpm motorsport unless I hear that it's not a good place.

Thanks for all your help.
 
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