Odd tranny shift bump at 50+mph - 95 540ia

[Skatingzooyork]

So when I bought my car, if I was cruising at 50mph; if I let go of the gas pedal and coasted and then started to press the gas again I would get this slight shift bump, almost like a very slight hiccup. The only other way I could describe it is that it almost feels like the throttle cables sticks for a 10th of a second but if that was the case, I would assume the speed wouldn't matter.

I assumed it was just kinda normal for the age of the car/size(first e34), but I've noticed over the past year that it's now doing it between 50-60mph; and only at those speeds. Same scenario, foot off pedal, coasting, then reapplying the gas (slowly, not stomping it at all).

I changed the tranny filter and fluid a little while ago(amsoil fluid/mann filter) and I'm planning to do it again(drain/refill) since I know you don't get all of the old fluid out in one shot but it didn't seem to affect the "bump" anyway.

Has any of the other 540ia guys experienced something like this? Thoughts?


And please don't just say, "time for a 6spd swap"; trust me, I would LOVE to do it but it's my DD and I just don't have the spare $$ right now to take that on. I'm really hoping to pick up an SUV for my wife and then I can do the 6spd swap this winter. Hopefully!!!! :crosses fingers:

Thanks guys! :buttrock

[Nuckles]

Mine does it to, I think its just the way the tranny response. It maybe in overdrive and then down to 4th gear and back up, long as it is not a harsh shift you should be okay.

[K Fox]

Dig this - you're describing the exact same thing my 94 540 did for the previous owner before I bought it. They took it to a dealer to have it looked at and diagnosed, and the master tech told them it was an intake leak that caused that little 'hesitation'. I always thought it was crap, as the auto tranny's have known issues with shrinking check balls, but I'm starting to get the same thing that you describe now in the new '95 540i6. Now I know the 95 has a leak or 2 in the intake, but they weren't enough to even trip the CEL till tonight. That said, I've noticed a progression in how much and how hard it 'hesitates' when getting back on the throttle since I got the car a couple of months ago. Now I'm starting to believe that master tech, 'cause I'm seeing the hesitation he was talking about. Sadly, he was wrong about the 94 - its problem was the valve body. If I were you I'd try testing for vacuum leaks with starting fluid, and of that doesn't find them then I'd consider going for a smoke test to find any leaks in the system. FWIW, I can't find any leaks on the 95 using starting fluid, so I need a smoke test to find mine. Another FWIW - I'm not gonna get that smoke test, I'm just gonna replace all of the intake gaskets as a bit of preventative maintenance at this point.

Fox

PS - I should clarify - the 94 had the starting from a stop hesitation in a bad way, but it did have a little of the coast then back on it hesitation also. So it had both, but the PO took it in for the starting off hesitation, and that's why I thought it was bunk, I knew it was in the tranny.

[Skatingzooyork]

Mine does it to, I think its just the way the tranny response. It maybe in overdrive and then down to 4th gear and back up, long as it is not a harsh shift you should be okay.

That is how I was originally thinking but then it got worse, well not really worse just "spread" more. So I doubt it's "normal"...


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Dig this - you're describing the exact same thing my 94 540 did for the previous owner before I bought it. They took it to a dealer to have it looked at and diagnosed, and the master tech told them it was an intake leak that caused that little 'hesitation'. I always thought it was crap, as the auto tranny's have known issues with shrinking check balls, but I'm starting to get the same thing that you describe now in the new '95 540i6. Now I know the 95 has a leak or 2 in the intake, but they weren't enough to even trip the CEL till tonight. That said, I've noticed a progression in how much and how hard it 'hesitates' when getting back on the throttle since I got the car a couple of months ago. Now I'm starting to believe that master tech, 'cause I'm seeing the hesitation he was talking about. Sadly, he was wrong about the 94 - its problem was the valve body. If I were you I'd try testing for vacuum leaks with starting fluid, and of that doesn't find them then I'd consider going for a smoke test to find any leaks in the system. FWIW, I can't find any leaks on the 95 using starting fluid, so I need a smoke test to find mine. Another FWIW - I'm not gonna get that smoke test, I'm just gonna replace all of the intake gaskets as a bit of preventative maintenance at this point.

Fox

PS - I should clarify - the 94 had the starting from a stop hesitation in a bad way, but it did have a little of the coast then back on it hesitation also. So it had both, but the PO took it in for the starting off hesitation, and that's why I thought it was bunk, I knew it was in the tranny.

You make an interesting case! I hadn't considered the intake but I guess it's possible. I'm definitely going to spray it down first; if nothing, I might just pick up a cai to avoid this problem in the future...

That would be great if that is my problem!





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[JoeFVaz]

If it happens in manual cars as well, I think it is right to assume that the problem is related to intake leaks.

[senatorfrisky]

it sounds like a lockup point in the TC. if you are coasting, under no load, the torque converter will lock up differently. maybe.

[napuli]

My 1995 540iA does the same thing. I would like to add that if I put the car on cruise control or sport mode the bumps don't occur as frequently. I talked to a mechanic who told me that it would be a good idea to check for possible updates for the transmission software. I never did follow up with him because I was convinced that the problem was not software based. At the time I was being paranoid that something was wrong with the torque converter. I would really like to follow up with this issue.

[K Fox]

... I might just pick up a cai to avoid this problem in the future...

Just so you know, a cold air intake isn't going to help this at all. It's leaks in the intake manifold itself that you're looking for. Things like the actual intake runner gaskets, the PCV plate, and the few vacuum lines in the engine. Those are wear the leaks will be that cause you grief.

That said, any CAI is going to be questionable - many have tried and none seem to do anthing for the cars. The stock airbox is very well designed and provides the best power for these engines. I read somewhere that BMW put a velocity stack in the stock airbox, and that makes a big difference. I haven't checked the inside of the airbox yet to see for myself, but I do know that the general consensus here is to keep the stock airbox. Good luck hunting leaks.

Fox

[Skatingzooyork]

If it happens in manual cars as well, I think it is right to assume that the problem is related to intake leaks.

Yeah that surprised me too!


it sounds like a lockup point in the TC. if you are coasting, under no load, the torque converter will lock up differently. maybe.

hum... but wouldn't that cause the "bump" every time it's under no load?


My 1995 540iA does the same thing. I would like to add that if I put the car on cruise control or sport mode the bumps don't occur as frequently. I talked to a mechanic who told me that it would be a good idea to check for possible updates for the transmission software. I never did follow up with him because I was convinced that the problem was not software based. At the time I was being paranoid that something was wrong with the torque converter. I would really like to follow up with this issue.

Well I know my CC doesn't work and I haven't messed w/ sport mode simply because I was getting worried that there was a tranny problem. Plus since 80% of the time I drive like a semi-fast granny, I have no desire to loose the 21.8mpg city that I've been getting by always being in sport mode. I guess there could be a software update but the PO was pretty anal about getting work done so the update would have to be within the last 1.5yrs.


Just so you know, a cold air intake isn't going to help this at all. It's leaks in the intake manifold itself that you're looking for. Things like the actual intake runner gaskets, the PCV plate, and the few vacuum lines in the engine. Those are wear the leaks will be that cause you grief.

That said, any CAI is going to be questionable - many have tried and none seem to do anthing for the cars. The stock airbox is very well designed and provides the best power for these engines. I read somewhere that BMW put a velocity stack in the stock airbox, and that makes a big difference. I haven't checked the inside of the airbox yet to see for myself, but I do know that the general consensus here is to keep the stock airbox. Good luck hunting leaks.

Fox

Yeah I knew the stock box was perfectly fine but I was thinking that the leak was on the intake tube inself not the on the manifold. :(

I guess I'm going to start checking for leaks and plan to do the gaskets soon.

[K Fox]

Yeah I knew the stock box was perfectly fine but I was thinking that the leak was on the intake tube inself not the on the manifold. :(

I guess I'm going to start checking for leaks and plan to do the gaskets soon.

Well, it's not that it can't be in the intake tube (the flexi plastic piece), but just be aware that you may have leaks from hardened gaskets elsewhere also. You may get lucky and only have 1 easy fix leak, but be aware that it might be more involved also. Here's hoping for easy!

Fox

[Skatingzooyork]

Well, it's not that it can't be in the intake tube (the flexi plastic piece), but just be aware that you may have leaks from hardened gaskets elsewhere also. You may get lucky and only have 1 easy fix leak, but be aware that it might be more involved also. Here's hoping for easy!

Fox


Yeah for sure! I'm going to go over it this weekend when I do my oil change. Hopefully I will have an simple fix but usually it never is in my case. lol

Either way, at least I have something else to look at instead of just a tranny problem.

[m60b30530i]

I had this issue in my 530ia, turned out to be the lock up solenoid, it got so bad it would shudder when I let off the gas cruised then re applied it.

[Skatingzooyork]

I had this issue in my 530ia, turned out to be the lock up solenoid, it got so bad it would shudder when I let off the gas cruised then re applied it.

Well that would suck! Did it happen over time or how fast did you notice the change/progression?

[m60b30530i]

Well that would suck! Did it happen over time or how fast did you notice the change/progression?

Right after my tranny flush about a week into driving it started as a small hic up then became a shudder. I just left it in S4 all the time because S4 doesn't go into over drive.

[Skatingzooyork]

Right after my tranny flush about a week into driving it started as a small hic up then became a shudder. I just left it in S4 all the time because S4 doesn't go into over drive.

Did you do a actual flush or just a drain/refill? I know a lot of people don't recommend a flush because it can free random debris and/or cause a lot of issues. I don't think it would cause a bad solenoid but definitely interesting cause of the timing.

Mine has very slowly gotten worse, so hopefully that's not the case for me.

[m60b30530i]

Did you do a actual flush or just a drain/refill? I know a lot of people don't recommend a flush because it can free random debris and/or cause a lot of issues. I don't think it would cause a bad solenoid but definitely interesting cause of the timing.

Mine has very slowly gotten worse, so hopefully that's not the case for me.

drain and refill

I do remember a local trans guy saying that the solenoid can be replaced, I just could never source the part.

[napuli]

I think that the solenoids are easily accessible. I actually took my car to a transmission shop but the car run fine during the test drive. The mechanic suggested to wait till the problem got worse. In reality I am just waiting to fix other more immediate problems but this issue is very annoying because it makes me paranoid about my tranny. When I have an extra $500 I will change the transmission fluid and filter and have then check the solenoids and software.

[Skatingzooyork]

drain and refill

I do remember a local trans guy saying that the solenoid can be replaced, I just could never source the part.


I think that the solenoids are easily accessible. I actually took my car to a transmission shop but the car run fine during the test drive. The mechanic suggested to wait till the problem got worse. In reality I am just waiting to fix other more immediate problems but this issue is very annoying because it makes me paranoid about my tranny. When I have an extra $500 I will change the transmission fluid and filter and have then check the solenoids and software.

Hum I assumed the solenoid would be in the transmission but maybe not. I'm gonna check my bentley.

And how would a new filter/fluid coust $500 for the tranny? I got amsoill fluid and a oe filter and it was like $100! If you bring it to a shop, it would be an hr at most...

[Skatingzooyork]

I'm starting to think it's not intake related because I put it in sport mode, which kept it out of overdrive and I didn't feel it once. I bet it has something to do w/ the solenoid... Still haven't researched it enough though...

[Nuckles]

There is a software update for the tcu for this car, it was back in 2000 to chane the eprom with the updates. Just goggle eprom updates bmw.

[Skatingzooyork]

There is a software update for the tcu for this car, it was back in 2000 to chane the eprom with the updates. Just goggle eprom updates bmw.


Thanks I will check it out!

[napuli]

You need to take the transmission pan out to replace the filter. If you do, the first thing you will see is the valve body with all the solenoids. The price is partially due to the cost of the OEM BMW transmission fluid. I would not use anything else.

[Skatingzooyork]

You need to take the transmission pan out to replace the filter. If you do, the first thing you will see is the valve body with all the solenoids. The price is partially due to the cost of the OEM BMW transmission fluid. I would not use anything else.

Ah ok, yeah I saw them when I changed the filter last. Should be a simple swap if that's the problem!

Thanks for the info!

[senatorfrisky]

i wonder if you can test solenoids by shifting to lower gears while coming to a stop. seems like it would be easier to notice a failure under a more extreme shifting than the comfy modes we're programmed with.