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A few miles from home today doing about 70 mph the car suddenly shuddered or hiccups for a few seconds like a downshift but not as harsh. It recovered then about a quarter mile later did it again for about the same duration. No warning messages were displayed like Trans Program
I turned around immediately and drove about 5 miles home without further incident.
Anyone have an idea what might be causing this problem?
I have an E24 and did the same thing, it was the crankshaft position sensor, hope that helps
 

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Discussion Starter · #24 · (Edited)
At this point, the general consensus seems to be cam or crankshaft position sensors, fuel pump, MAF, or sparkplugs. I'm happy so far no one has mentioned a tranny malfunction. I hope that each of these has a specific code associated with it so I will know what to replace.
 

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That's a lot of parts to throw at it which is why we need codes to improve our guessing.

Ground strap no codes.
Crank sensor has a code but rarely shows it.
Cam sensor has a code but doesn't always show it.
MAF has a code but often doesn't show it.
Sparkplugs don't have specific codes but are likely to show as misfires.
Fuel pump is likely to show as lean codes, fuel trims or misfires.

Upstate New York
Too far for me to either help or take it off your hands.
 

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Discussion Starter · #26 ·
You are correct that getting the codes would hopefully put this thing to bed but apparently according to you most of the usual suspects forum members have identified will not even throw one, which leaves me with no alternative but to use the "shotgun approach", keep changing parts until one works.
 

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Wingnut
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if thats your choice, its your car. and your money. dismissing the possibility of codes and live data from the car so readily has cost a lot a people a lot of money.
 

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Discussion Starter · #28 ·
No please don't misunstsnd me..of course I want to have the codes but u nanimous states that many of the potential culprits don't even throw codes so if that's the case why bother worrying about scanning at all? Having state of the art BMW hardware and software would make no difference, assuming u is correct, if there are no codes to detect.
Therefore without this vital information what alternative do I have but to replace one part at a time until finally the hiccup disappears
 

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Scanning for codes, or lack of codes, and looking at other data like fuel trims can help eliminate items off that list.
 

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Discussion Starter · #32 ·
Thanks and to be perfectly honest that was my initial thought too (I think I mentioned it in my first post) If the damn car had a dipstick I could have checked it a long time ago but I have to take it to a garage that has a lift
 

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Discussion Starter · #33 ·
Hmmm. I just checked under the car and saw a wet area on the driveway near the front close to where the radiator sits. Popped the hood but could not see any fluid accumulations. I'm wondering now if may a tranny cooler hose or fitting might be leaking? I need to do some further investigation
 

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Discussion Starter · #36 · (Edited)
I haven't driven the car in a month until today. Drove it from my house about 6 miles in traffic and had no problem then jumped on a highway. After about 3 miles driving at 70 mph it very slightly hesitated for just a couple seconds (and it was much milder than the first time around) but then no problem until I recached my destination about 10 miles away.

Returned home the same route with no issues until about 3 miles from home as I turned a corner it stayed in 3rd gear (or it may have been 2nd) when it should have shifted into 4th (or 3rd) for about 15-20 seconds at which time it finally upshifted.

No messages came up either such as the dreaded "Trans Program". Wondering now if low fluid as someone said above is the problem or is something else.
 
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