Slow acceleration

[croyhenric22]

Hey everybody, I recently bought my first bmw. its a 2006 325i and i'm loving it. I do have a couple issues I need to fix tho. First is the dealer replaced all the brakes before I drove it off the lot and never replaced the brake sensor. Thanks to a few threads on here I think i can manage to fix this on my own.

Second is a much bigger problem that i'm not sure i can fix myself. When I accelerate from a stop, the car seems to hesitate. Then it shifts to second gear and drives normal. It didn't drive like this on the test drive so when it started to do it the day after i bought it, i took it back to the dealer immediately. Thankfully they took it to their garage asap. At first they said it was the ignition coil so they replaced that but it still didnt drive right. Then they said it was driving fine. I still think it hesitates bad tho. I have heard from another person that all BMW's do this, is that true? If not what else can it be? There aren't any lights or warnings on except for the brake light either. Any thoughts on this issue?

And the third issue is much smaller and only happens when its cold out and the car sits for hours. None of the gauges will work for about a minute or two then they start working normally. this doesn't relly bother me much since it only lasts a few minutes but I thought I'd see what you all think about it.

Thanks for you help in advance!!
Cory

[Jack Dabsy]

Hi Cory, welcome aboard matey !!
Your second issue could be something as simple as cleaning the throttle-body and/or MAF... I cannot be certain unless I were there to experience your issue first hand !

[rivroshaun951]

I am not a professional. This is just my opinion. I could be wrong.

Questions.

1. When coming from the stop does the rpm's go up high?

2. Does the car act like it's going to stall?

3. Is this an automatic or manual?

4. Do you have any loss of power at any other time (going up hill WOT etc)?

5. Have you performed a vacuum gauge test and what were the results?

6. How hard are you accelerating out of the stops?

[croyhenric22]

Originally Posted by Dabsy

Hi Cory, welcome aboard matey !!
Your second issue could be something as simple as cleaning the throttle-body and/or MAF... I cannot be certain unless I were there to experience your issue first hand !

Hey Dabsy, thanks for the suggestions. I'm not really mechanically savvy but I'll look into the things you said.

[croyhenric22]

Rivroshaun,
1. No the rpm's don't go up at all when coming to a stop. The car runs like a champ except when taking off from a complete stop. It seems like its just first gear.

2. No its not a stalling action more of a loss of power until it shift to second gear.

3. Its automatic.

4. Nope, no lose of power at any other time. just starting from a stop.

5. No, i haven't done a vacuum test. I took it back to the dealrr and just assumed they did the tests it needed (big mistake on mypart). Would any garage be able to do this test?

6. If I accelerate normally, it loses power pretty bad. But if you really step on it its not as noticable, but still nowhere near a normal acceleration.

Thanks for helping out! If you have any other suggestions of things to check or test please let me know!

Originally Posted by rivroshaun951

I am not a professional. This is just my opinion. I could be wrong.

Questions.

1. When coming from the stop does the rpm's go up high?

2. Does the car act like it's going to stall?

3. Is this an automatic or manual?

4. Do you have any loss of power at any other time (going up hill WOT etc)?

5. Have you performed a vacuum gauge test and what were the results?

6. How hard are you accelerating out of the stops?

[rivroshaun951]

I am not a professional. This is just my opinion. I could be wrong.

Okay now that I know a little bit more information about the car. We need to see if this is a engine performance issue or a transmission issue.

Vacuum Gauge test: This is a very easy test to perform and yes all shops should be able to do this. A Vacuum Gauge test is automotive repair 101.

My advice to you is to save your money buy a vacuum gauge kit and do it yourself. This is a tool that you will keep for life and use every time you buy a used car.

A vacuum gauge test will tell you how well the car's volumetric efficiency is. You can find problems such as intake manifold leak, valve timing issues, misfires etc. just from this test a 6 year kid can do.........okay maybe 12 year old can do.

Now since you don't have a vacuum gauge kit with you there is a very easy test we can do with your transmission that the only tool you will need is your eye's ears and foot.

Stall Test: This simple test will help you cancel out a transmission problem.

Why I think so: Inside your torque converter is a stator (one way clutch). that is designed to multiply torque and give you that push you need why coming from a stop. this stall test will help you determine if the stator is slipping. The stall test can also help with finding out if you have any slipping clutches in your transmission. Find out the manufacture specs for your car.

If your car fails the stall test:

Test is bellow specifications. This is a sign of poor engine performance (don't have enough power). or the stator clutch is slipping (not enough torque multiplication).

Test above specifications. You could have a slipping band or clutch.

If the stall test pass and your car has poor acceleration (through all gears). I would suspect a seized one way clutch (stator).

Start with these test first. Oh and I highly doubt that BMW would design a car to fall on it's face coming from a stop.

Also it strange to me that the shop would diagnose the ignition coil as the problem. I think maybe the ignition coil was going bad however might not have been the reason for your problem. You see whenever the ignition system is bad (secondary and primary). The problem will normally get worse as engine speed increases. You are telling us the car is a Champ at higher speeds. Based on what you are telling me. I would expect car breathing problems (Volumetric efficiency). When you have breathing problems the normally go away as engine speed increases or is less noticeable.

[chapman]

Hi im new to this site but I come bearing good news,
I have had the same problem as above since I have changed the Crank Shaft sensor on my BMW 316i E46 (N42 engine). I have put it on my code reader tonight and I have had a code P0327, Looked on the internet and that was a Knocking Sensor.

I then went and traced the sensor cables (underneath the right manifold) and found that the sensor had come disconneted.

I suggest that if you have the same car or engine and have the above mentioned problem then Check the connection. You can see the plug if you look just left of the OIL filter housing and Mine was a green ended plug which stood out like a sore thumb once I new what I was looking for.

It should connect to the plug that is in a clip type thing facing away from you.

Hope this helps.
Wayne.