3rd gear hesitation or something...

[kpro]

My car only does this in 3rd gear, and its very random but doing it more often than not at this point. This happens during acceleration, never while cruising. I have to shift into 3rd from 2nd to make it happen, never on downshifts. I wouldn't call it a hesitation per say...it almost feels as tho its coming from the back end too, but that could be BS. The car doesn't bounce, but it feels like something is lumpy.

The only reason I mention it is because I had a passenger ask me WTF is wrong with my car today, and I have been used to it for some time now. Any ideas? Nothing seems weird when I put it on a lift. Nothing leaks. I'm worried its transmission/diff related.

Any Ideas or anyone heard of this?

[ryankokesh]

:dunno

[Mtnman]

Is it immediately during engagement of the gear, or after you are in 3rd gear for a second or two?

[ZSP-Mafia]

How does your diff bushing look?

[kayger12]

If you shift at a higher rpm does it still do it?

Droid X. Tapatalk. Use it.

[kpro]

Does not do it at higher RPMs, it does it about a second or two after I shift into 3rd. If I shift at higher RPMs things are a-ok!

[RITmusic2k]

Are you absolutely convinced it's not engine hesitation? 3rd gear between 2,800 - 3,000rpms is where my hesitation problem is most apparent. It's there in the higher gears as well, but the rate at which the car pulses is reduced so it's harder to notice. But your situation does seem to fit the scenario.

I'd suggest that you try a rev-sweep in 3rd, and notice when it starts and how long it lasts. See if it starts at the same RPMs every time. See if it makes a difference whether you're at full throttle acceleration or part-throttle acceleration. If you find one consistent method that produces the symptoms the same way every time, I'll bet it is actually the firmware gremlin.

[kpro]

Thanks. I know that its only under part-throttle acceleration, never when I floor it. I will report back after lunch, I'm going to drive her around and see if I can get a more solid scenario for you guys.

[kayger12]

I'm thinking Vanos... Try with your AC on and see if it gets worse.

[kpro]

I didn't see the post about the A/C til now, but when I drove around I noticed its between 2500-3500 RPM at partial throttle. WOT it doesn't do it.

[Mtnman]

WOT? what does that mean?

[Hornung418]

WOT= Wide open throttle

Reads like a VANOS hesitation or a firmware issue is to blame. Do the A/C test as Keith suggested. If it is worse, you potentially need to re-seal your VANOS pistons.

[RITmusic2k]

"Wide Open Throttle"

Hmm. Well, that's not exactly like my problem, though mine also only occurs at partial throttle... mine stops exactly at 3,000rpms every time. Can you feel anything similar in higher gears? Maybe more subtle, but still there?

[Mtnman]

"Wide Open Throttle"





:facepalm Shoulda gotten that one. Been working too long today without a break.

[kpro]

^its otay. I forgot to do the A/C test. I will do it in the morning on the way to work. I haven't noticed anything in other gears at all. It may very well stop at 3,000 RPM, but I think It went to about 3300 before I couldn't feel it anymore.

Thanks for your help so far guys :)

[kpro]

Can NOT duplicate the hesitation/lumpyness with A/C on. I tried on the way to work and for an hour of my lunch today. I called about the DME reflash, do you guys think that is the way to go with this? I can't recognize any vanos failure symptoms...I do have a very ever so slight rattle at idle and thats it.

[RITmusic2k]

It's as good a guess as I can venture without also knowing much about VANOS symptoms and without having resolved my own issue with a DME update yet. Worth a phone call to the dealer at the least...


So, wait a minute though... are you saying the problem is entirely gone when the A/C is engaged? I need to test whether that has any effect on my car. Hmm.

[kpro]

I tried and tried to duplicate the problem with A/C on with no luck. I will drive home with it on too, and try again. I called the dealer and they acted ignorant, told me to stop reading into what the internet says, lol. I need to go up there, they are always more willing to help in person.

[kpro]

UPDATE: This hesitation is getting much worse. I've narrowed it down to 2700-3100RPM or so, and it does it in 2nd, 3rd, and 4th gears now. If you give it more than about 75% throttle, it will not duplicate. It has to be around 1/2 throttle or less. I've found that it does get worse with the A/C on. Its not bad enough to make the CEL come on tho :( I wish it would just throw a code so I could start somewhere.

Anyone have a good VANOS diagnosis thread they know of? I don't know if that could be it or not. I don't have the rattle. I have a touch of a rattle at idle, but thats it. I keep reading all this stuff and it seems like I'm just walking in circles.

[kayger12]

Man-- it's screaming Vanos, Kristen. The rattle and the Vanos seals going bad are two separate issues.

From the Beisan site

Vanos Seals Failure Symptoms
Overall loss of torque and power, particularly in the lower RPM range, < 3k. Bogging then surging at 3k RPM. Uneven power distribution and RPM transition. Engine hesitations in the lower RPM range, < 3k. Louder idle and intermittent idle RPM hiccups. Difficult takeoffs. Loss of power and bogging when AC on. Increased fuel consumption. Vanos fault codes.
Double vanos cars with the M52TU engine (98/99-00) experience cold weather cold start idle jolts and possible stall.

[Hornung418]

Add yourself to the DIY Day list for VANOS :)

[kpro]

CRAP. FUCK. DAMN.


Thanks Keith for posting that/confirming my suspicion. I really don't want to miss the mafia family reunion because of my car :( I don't have time to take care of this before then, and its much worse now then it was a few weeks ago. I haven't had the time to do the cooling system crap either. I guess I need to figure out what my car thinks is priority at this point then maybe take another vacation day and fix it.

Horney:
I dunno, maybe I should stay for Sunday and do it at the DIY day...I will have to take extra time off work and stuff.

[Hornung418]

VANOS is pretty easy esp for a car savvy person such as yourself.

[kayger12]

I would just try to deal with it until the meet and take care of it there.



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[Marcus-SanDiego]

Nice. I can watch you guys fix it at the meet.

[kayger12]

I would do cooling before Vanos.

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[kpro]

Cooling System should only take me like an hour or two...Its just that I have had ZERO free time, unless sitting here on my butt at work. I have every weekend booked til Mid-June :( I will do the VANOS at the meet tho :)

[danewilson77]

Nice. I can watch you guys fix it at the meet.

We will be doing 5 of these at the meet...lol.

[danewilson77]

Cooling System should only take me like an hour or two...Its just that I have had ZERO free time, unless sitting here on my butt at work. I have every weekend booked til Mid-June :( I will do the VANOS at the meet tho :)

If the cooling system takes you an hour or two.....I will hail you as Goddess of The E46.

[kpro]

Should I take a day off work and to do this before the meet then since there are so many trying to do theirs? I can probably figure it out on my own, I just rather have one of you BMW guys there when I mess things up and try to put the timing chain on inside out :)

Oh, and I'm pretty sure the cooling system stuff should take about an hour and a half or so.... not including bleeding the system. I did my buddies 323Ci a few months back after his expansion tank grenaded, and it wasn't too bad.

[Hornung418]

Should I take a day off work and to do this before the meet then since there are so many trying to do theirs? I can probably figure it out on my own, I just rather have one of you BMW guys there when I mess things up and try to put the timing chain on inside out :)

Oh, and I'm pretty sure the cooling system stuff should take about an hour and a half or so.... not including bleeding the system. I did my buddies 323Ci a few months back after his expansion tank grenaded, and it wasn't too bad.

Timing chain doesn't come off. It stays on the cams. The unit seperates from the head as a whole. The only thing connecting the two are the vanos bolts which are reverse threaded :)

DROIDstatus. Come at me, bro.

[danewilson77]

^Yup. Read the procedure at the Beisan site and get knowledgeable on the procedure. It will help.

You could knock it out yourself, or do it at the meet. We can support.

[ryankokesh]

If a half-wit like me can do it, you'll have no problem.

[UncleSmitty]

So, a question - does the vanos problem normally cause the same hesitation at full throttle? I ask because I have had similar problems on a previous car, and it ended up being the fuel mixture causing hesitation due to incorrect o2 readings at part throttle. Once at ~80% throttle the car would go into PE mode (power enrich) and used a preset mixture setting instead of the o2 sensor, and the problem went away.

A simple way to check without having to open the hood is to try to duplicate the problem when the car's cold - I'm not 100% sure the e46 is set up the same way, but on my old car the ECU would ignore o2 readings for a short time while the car heats up (and my problem went away then too).

[kpro]

I have no hesitation if accelerating over half throttle maybe its closer to about 60% throttle, I dunno. It does it once warmed up, not really much when cold. But I have a faint but distinct rattle at idle as well. I'm getting about 4-5mpg less than I normally do. After reading the Beisan thing, I'm pretty sure its Vanos.