bmw 645ci,pulsing, jerking,uneven throttle body response at low speed/RPM in 1st gear

Now to my problem:
I took my car to the shop today! we checked the battery and this time it was at 81%. Does it mean the battery is good?! the battery is a "Duralast" from autozone .Is it a good battery or I should get a BMW factory battery in? also, we replaced all coils . The coils looked really bad! some of them were loose and came out easily! After replacing the coils, the car run much better overall, but I still have the low speed hesitation and poor light throttle response so What its gonna be the next step ?
Is it possible to have a bad camshaft without throwing any code?
should I replace the battery with a BMW factory one? or trying to reprogram the whole car again?!
Btw, I cleaned the throttle body valve once before ! Do you think It might be damaged ?
Thanks again

I don't want to sound disconnect to the hardship of today's life, IMHO I really think you will be better off if you take the car to the dealer and let them fix it once n for all, all these fixes here n there, and take things apart and put them back together is only asking for more trouble and they cost money, them small fixes add up real quick. unfortunately it sounds like you and your mechanic kinda lost a lil bit.. I no the stealer will charge but at least at the end you will be happy and go back to enjoy your baby. I'm afraid after this is set and done you might dislike her.. I don't know.

Originally Posted by aarash2000

Shan 904,
I had the same problem before! exactly between 35-40 mph! unfortunately, its the transmission, the valve body/mechatronics. I got new transmission under warranty! its not going to be cheap if you out of warranty A friend of mine fixed his 745I under 1500 $.
take a look at this: http://www.bimmerfest.com/forums/sho...d.php?t=654634
It might work for you too!

Ugh...I was afraid of that. Thanks for the lead on replacing the solenoids. I'll have to look into it.

Thanks carter650! To be honest, I have taken the car to dealer already. they kept the car for 2 days and could not find anything! the problem is the car doesn't throw any error! Stealer said they can't do anything if there is no code! stupid... !!!

Oh ok, I did not know that, but then again if I were u I would have BMW USA involve and insist that the dealer being lazy and refuse to go beyond stupid error code to fix the car.

You will find out that BMWNA does not care about cars out of warranty! If the battery is good, a new BMW/Excide battery will not fix the problem. Have you had the battery load test, after a full charge? 85% still does not sound correct. If your Vanos solenoids are sticky & not working correctly, it could do this without throwing a code. You and someone else, are going to have to run all diagnostic checks on the DME, one by one. You will have to check each test for numbers that are outside the set limits. Once you find out what is wrong, then you will have to figure out what is causing the issue. The software will not tell you how to fix the problem, but it will tell you what parameters are outside the set limits. This could take 2 hours or 2 weeks. It is not fun, but I think it is your only option.

Good Luck!

Thanks HerbP. Your probably right ! hope I dont need to go that far
Anyway, I just drove the car after sitting for 24 hours! No more harsh shifting at cold start . drives much smoother when the car is cold! before, when the engine/transmission were cold, I had harsh shifting for the first couple minutes till the tranny and engine got warm! but, today, I wasnt the case! So at least we solved one of the problems BUT, I just notice something else. that might be my main problem I guess! hmm Its hard to explain ! I noticed when the car is in P at idle and you give some light throttle, So like to 2000 rpm and then When I lift off the throttle completely, I feel like my RPM's drop much faster than they should, it drops back too quickly instead of coming back to idle smoothly! for example I push it a little to about 1500 RPM's and then let off the gas completely before the engine can upshift to the 2nd gear , RPM's drop to around 550 in at most 1 second. That also happens in P,R,N,D regardless! I think thats the cause of histitation/pulsing at low speed/RPM! it only happens in 1st gear! !!! please let me know What do you think?! which module can cause this? Thanks

Originally Posted by aarash2000

Thanks HerbP. Your probably right ! hope I dont need to go that far
Anyway, I just drove the car after sitting for 24 hours! No more harsh shifting at cold start . drives much smoother when the car is cold! before, when the engine/transmission were cold, I had harsh shifting for the first couple minutes till the tranny and engine got warm! but, today, I wasnt the case! So at least we solved one of the problems BUT, I just notice something else. that might be my main problem I guess! hmm Its hard to explain ! I noticed when the car is in P at idle and you give some light throttle, So like to 2000 rpm and then When I lift off the throttle completely, I feel like my RPM's drop much faster than they should, it drops back too quickly instead of coming back to idle smoothly! for example I push it a little to about 1500 RPM's and then let off the gas completely before the engine can upshift to the 2nd gear , RPM's drop to around 550 in at most 1 second. That also happens in P,R,N,D regardless! I think thats the cause of histitation/pulsing at low speed/RPM! it only happens in 1st gear! !!! please let me know What do you think?! which module can cause this? Thanks

My 1st question is, what did you do to the car differently last night? What do you think made it run better? Was the ambient air colder or warmer?

The RPM's dropping faster or slower is most not likely linked to a problem. When the pedal is released, the throttle should snap closed. A vacuum leak or possible CCV valve could be causing an erratic idle?

Have you serviced the transmission or checked the fluid level lately?

I do not think that you have any module problems, but something effecting the engine response. Has anyone measured the vacuum at idle? Has the TPS been checked for the proper setting? It sounds like you have made some improvement lately, but a lot of repairs were made at one time. This being the case, you are going to have to check/inspect everything that might have been touched! There are just to many variables that could have been changed.

You might need to find a new tech to check the car over!

Good Luck!

Originally Posted by aarash2000

Thanks carter650! To be honest, I have taken the car to dealer already. they kept the car for 2 days and could not find anything! the problem is the car doesn't throw any error! Stealer said they can't do anything if there is no code! stupid... !!!

Transmission Solenoids.

I know I'm coming into this late but I had a similar problem with my sixer. The car would lurch from a stop and when i would brake the car would lurch just as it was coming to a complete stop. I would have to keep my foot firmly on the brake peddle at a stop.
I took the car into the dealer and long story short they decided to replace the torque converter and that fixed the problem. They where stumped as to what could cause that kind of problem and had to go to BMW for the fix...
Good thing the car was under warranty still as it was about a $6000 repair job... never had the problem again...

Thanks for your comment! The transmission on my car was replaced like 20k ago under warranty! Hope it's not the case again! Now, the car runs MUCH better after replacing the coils!no more hard shifting much better at low speed! The old coils looked really bad! Im wondering why we didnt get any code for it!!!! They were all loose! Now, waiting for the camshaft sensors to to come in and see what happens after replacing! Should improve the low speed hesitation! !!! I'll keep u guys updated! Thanks again!

Hi,

Did you ever get to the bottom of the intake manifold pressure sensor problem?

Also, with certain diagnostic equipment you can check running roughness for each individual cylinder. Maybe this will show a cylinder is running rough- but not quite enough to trigger a fault code. If it is an air problem (too much/little) this would cause problems with the vacuum pressure in the intake manifold.

What do the spark plugs look like for each cylinder? This might help diagnose the problem.

Good luck!

Andrew

Thanks everyone for you inputs. I think we finally fixed the problem! We replaced the 4 camshafts sensor and now the car runs prefectly again! the funny part is that I did not have any code for camshafts sensors! we replaced the camshafts sensor along with 2 pre cats O2 sensors today! I drove the car for like 100K today and I did not notice any histitation at low speed. The throttle response is the way it should be very happy now A friend of me did the same thing with his 2002 745i and that solved his problem too! He was diagnosed for bad Valvetronic intermediate levers ! He wanted to sell his car but he decided to give it a last try! He replaced all 4 camshafts sensor and his car runs Ok again! He also did not have any code for camshafts sensor! Anyway, I will drive the car for couple days and hope it stays that way!

Glad to here the problem is fixed!! I love success stories enjoy your time with your fixed 6er....Cheers!!!

I would recommened anyone to replace the camshafts if you are over 80K. Its only 50 dollars each! You will feel the difference! Dont rely too mich on your code readers!

Thanks Nitrogen, I think its the time to enjoy my 6er finally

I got 129K on mine and have only replaced 1 so far maybe you are right I will replace them all!!!!

Yes. I think It would be a good Idea! you will feel the difference! Also, replace the 2 pre-cat O2 sensor if you havent done it yet!

My '10 650i lurches for like a minute when cold. Any other start the rest of the day...no problem. Even when it sits at work for like 6-8 hrs. Weird. Usually out of my driveway, and I have 2 stop signs in span of like 250 yards so I'm going pretty slow. Once I can get up past 15 or 20 mph - no problem.

Do you also have harsh shifting for the first couple mins when cold!? Specially, 1st to 2nd gear?!

No. Just kinda lurches when going slow. If I could accelerate to a decent speed I don't think it would happen.

How many miles you got on your car!!? Do you get any code?! It might be your coils as well! Check the condition of your coils and see if they are loose\bad! I had kinda same problem and also harsh shifting when cold! I replaced all coils and it solved the problem ! My coils looked really old and they were all loose!

Hmmm...
Have 55,000 miles