BMW CCA Member
What better way is there to diagnose a problem than by throwing money at it, ha! About the only electrical parts I have not replaced under the hood since putting car on the road were the MAF sensors. So I ordered two Wednesday night from a Walker Products supplier and they showed up Saturday afternoon by way of Fedex without shipping charges. Price on the parts was apprx $135 each.
Since the sensors on the car looked like the original parts I thought I might find an improvement with gas mileage and possibly eliminate the intermittent running problem. I tried the 'idle' test and when car is cold and sensors are unplugged at separate times the idle would drop down. I tried it a couple of times after driving the car and warming up the engine and I noticed that the left bank idle did not change so I thought sensor just might be bad.
The Walker sensors are brand new, housings appear identical to the original parts, but they are an updated design which eliminates the very fine hotwire. Maybe the new design will be an improvement. There are two standoffs in the inner velocity tube instead of one in the old design. I installed them and started the car. The idle wandered for about five minutes and settled down. Drove across town and engine ran fine.
Then today I went for a test drive. Started the car and check engine light came on for the first time. Turned off the car and did the stomp test. Still throwing code 1247 but now there was a new code 2235 which I haven't identified yet. Started engine and check light disappeared. I drove the car pretty hard along expressways and it ran great but after an hour it finally went in trans failsafe mode. Just before going to in lhm i could cruise along about 65mph and let off throttle slightly and I would notice a hesitation and I could not get back into power until I left off throttle completely then it would have full power and accelerate normally. After a mile or two it went into lhm.
So I drove a couple of miles and stopped at the store. 30 minutes later I returned to car and it ran fine back to the house. So I am still mystified by this intermittent problem. Car runs great otherwise when its not in lhm. Maybe one of the new coils is bad? They ohmed out okay when I last checked. Maybe I need to get it into lhm and check coil resistance afterwards.
Car really rips when in 3rd gear 'sport' mode. Is there a second map loaded in the DMEs for this purpose?
Here is a photo of the new sensor
IMG_20180331_171804179.jpg
IMG_20180331_170136226_HDR.jpg
BMW CCA Member
BTW, I ohmed the donuts a week ago and one appeared to be bad even tho it was a brand new aftermarket beru wire set. I subbed the old oem wire on bank 2, but i have not subbed the other oem wire for the new donut that is still on the other bank. Maybe this will solve the problem. Bank 2 is throwing the 2235 code if anyone knows what this refers to.
Ultimate Machine Driver
Hows your distributor caps and rotors, They look good? Spark plugs all tightened down.
BMW CCA Member
All ignition parts and fuel system parts are new. I will sub in the BMW spark plug wire donut and see if that helps. If not I have two more new coils I can try.Originally Posted by 8eights
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BMW CCA Member
I remember having the same code, installing correct spark plugs, new wires and ignition coils fixed the problem..
It could be resistance of spark plugs and/or wires to high bad donuts, bad coils or all of above at the same time... Car had 120k with all original parts (except incorrect spark plugs)
91 850i 59k
Member
I have some bad news for you. The walker mafs are no good, look through the maf as you can see they have a single wire element from China same as all those ebay mafs.
All they do is make the car run like crap, been there done that. Also the longer you drive the worse the car runs.
Best way to go about this is to purchase used 2 good OEM units.
BMW CCA Member
Car has new NGK plugs, Beru wires with aftermarket donuts, new Bosch caps, rotors,and coils. I have replaced one donut with the old BMW wire from harness I replaced. I will replace the other wire and donut this evening and see if it makes any difference.
Car ran great yesterday with the new Walker MAF sensors. It really rips especially in 'sport' mode but after driving it pretty hard for an hour it went back into lhm like it has been doing previously before I changed the mafs. There are 'two standoffs' in the Walker units eliminating the very fine filament. I do have the old mafs and there may not be anything wrong with them, but I did not know how to test the accurately other than pulling plug while idling to see if engine speed dropped.
Maybe the new aftermarket donut is bad. I will try to replace it this evening and go for a test drive. I an also change coils again because i have two new Bosch coils.
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I had Beru wires that the PO fitted and they were the source of my running issues when I had the exact same symptoms as you. The Beru wires don't come with the CIS so the one you have is probably original. The issue is the snap on connection of the wire to spark plug boot (so that you can slide on the CIS donut). On mine this snap on connection was poor on one side, so the current was effectively jumping constantly. It worked okay for a while but over time it got worse and more corroded until there was little or no current reaching the plug and, detecting this, the donut sensor shut down the bank with greater frequency until it would only start one one bank.
Replaced with a new OEM wire and everything was hunky dory (until the next thing went wrong!! haha). I did subsequently replace all of the cables with OE from a good used set I found in a wrecked E32.
BMW CCA Member
Thanks, Jeffbebe!
I bought a new set of wires from Turner made by Kingsborne in CA using Beru connectors with donuts already installed. Set has only been on the car for the past month or two since I started running the car. I did ohm the donuts and one of them seemed to be two or three times higher resistance, 1.5 to 1.9 ohms, instead of .3 like the other new one and the old ones I took off. So I ordered a replacement wire with donut installed, but I had already installed the old oem wire and sensor. The donut on other bank tested okay but I will replace it with the old oem bmw wire/donut I took off originally and see it it makes a difference. Its just odd that its usually an intermittent problem and most of the time the engine runs very well. I am pretty darn impressed with the power and torque of the V12, especially in 'S' mode!
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Agreed! I'm lucky enough to have had the opportunity to take mine out on a closed road and can confirm that she was still pulling hard at 220km/h. Mine is delimited but I've never reached top speed. Whatever it is, my balls aren't big enough to test it!! haha
BMW CCA Member
I will probably track my car occasionally once problems are sorted out and new suspension is installed which should be pretty soon. There really isn't a safer place to run at speed than running on a closed road course.
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Read this article...
https://www.nytimes.com/2009/04/26/s...26bigbend.html
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Wow, just reading that article got me very excited. Would be an excellent opportunity to let the 8 gulp in the air at long stretches.
BMW CCA Member
All I see with link are adds. Anyway, the Big Bend Open Road Race has been going on 20+ years. I had thought about running one of my old bmws out there but I never did go. A few friends of mine have run the event. If you have never run before you have to start out in slowest class if I am not mistaken, and work your way up to the faster classes your car is capable of running if you have the proper safety gear. https://www.bborr.com/#
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I don't control the NY times. I guess you have to click through to get to archived NY Times articles.
I think there is the same kind of thing in Nevada somewhere too.
BMW CCA Member
https://www.bborr.com/index
This looks like a bunch of fun.
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