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Discussion Starter · #1 ·
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?
 

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Discussion Starter · #3 ·
Yeah that sounds plausible but as we know tranny issues can be tricky to diagnose. The list of potential suspects goes on and on.
I've replaced the input and output shaft sensors and changed the fluid and filter a few times but that's the extent of work done on the tranny. The wiring harness with all the plug ins has never been replaced however.
Could low fluid do something like this? Again, it hiccuped only for a few seconds both times and only at highway speed
 

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Discussion Starter · #6 ·
Thanks guys for the insights. Well, the fuel level was over 1/2 tank so it wasn't low fuel but I've never replaced the fuel pump and I've owned the car since 2008 so I suspect it's original. Could a semi-clogged fuel filter be the problem? I'm just thinking off the cuff that this could cause the fuel supply to blip for a few seconds? I replaced it once but that was several years ago.

Camshaft position sensor? That's intriguing. I never would have thought of that and I've never changed it. Would the cam sensor or fuel delivery interruption (for whatever reason) throw a code? If so, would I need a special BMW code reader to see the code(s) or could a trip to Autozone accomplish the same thing?
 

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Discussion Starter · #11 · (Edited)
Great insights Mayor Chuck. I know the local Autozone will read the codes but that's it, they don't clear them afterward. I'll have to find a shop that will do that which is no big deal. I read somewhere that both the crank and cam position sensors communicate with the DME but the most likely culprit in my case seems to be the cam sensor. As you said, the MAF, I understand, can also be the problem.

Couple questions. If it's the MAF, is it just a matter of decarbonizing it or would it have to be replaced? This is another part in my car that I'm certain is original. If it's the cam sensor, is this an easy swap out for a non-mechanic like me or is it best replaced by a professional?

Also, thanks to everyone who has posted!
 

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Discussion Starter · #13 ·
Sorry, my bad. I was thinking about the throttle body not the MAF when I mentioned carbon build-up. I didn't realize basic OBD II scanners where so cheap so I will take your advice and buy one, thanks. That will really come in handy. It's an M62 in my 2000 740il.
If either one of these (MAF or cam sensor) ends up being the source of my problem, is it a OK (or not) to drive the car until I can get it repaired? In other words, I don't want to do any harm or end up at the side of the road. I haven't driven it since the incident.
 

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Discussion Starter · #14 ·
I see quite a few scanners advertised "for BMW". Do I need one of these (and most are over !50 dollars) or just any old garden variety OBD II scanner? Do the BMW scanners give more specific or detailed information or maybe it's just hype.
 

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Discussion Starter · #17 ·
Wow, that's a lot of information,( some of which I actually understand lol). It will take me some time to sort through it all or I could just take the coward's way out and pay my local indy a few bucks to scan it for me lol
 

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Discussion Starter · #19 ·
Good points for sure. I hope to keep the car as long as possible but, as everyone who owns an E38 knows, it's a constant battle to keep up with repairs so it's a precarious situation. The "to do" list of things that should be done to the car never gets shorter.
I don't want to invest in a BMW scanner because for one I'm not a diyer and two the car is one major repair away from being sold "as is' or even junked ,although I'd rather not do that.
 

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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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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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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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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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