Jerky Acceleration

[RyanOaks328i]

Question: I've got a E46, 99, 328i, 5 speed, 124K miles.

When accelerating, if the RPM is low (800 - 1500), the car jerks or momentarily loses power multiple times. I've noticed it more when the car is warmer or weather is hot. If you keep the RPM higher during acceleration it isn't noticable.

I'm guessing it a sensor, like the throttle position sensor.

Anyone have an educated guess on how I can fix this myself without taking it into a dealership and hooking it up to their computers?

[andrew325ci]

congrats on first post, sorry can't help

[Vicious I6]

Find somebody in your area with a code reader or go to your local auto parts store and borrow theirs. Read any codes your car is throwing and you can start diagnosis from there...

[pphil09]

IDK, seems a little normal to me, just cause the RPM's are so low...

[dello]

get an oil change. My 330xi was doing the same thing-i thought i needed a transmission, but i did an oil change and it's perfect now!

[RyanOaks328i]

Trust me, it's not normal. Imagine the engine producing absolutely no power for a sub second, then normal power for 3 seconds, then repeat a few times.

Aggressive driving seldom produces the problem. But when grandma is in the car and you are trying not to scare her, the jerking isn't pleasant.

[RyanOaks328i]

Transmission oil change or engine oil change?

[Smilez]

fuel filter change ?

[2002Z3]

Question: I've got a E46, 99, 328i, 5 speed, 124K miles.

When accelerating, if the RPM is low (800 - 1500), the car jerks or momentarily loses power multiple times. I've noticed it more when the car is warmer or weather is hot. If you keep the RPM higher during acceleration it isn't noticable.

I'm guessing it a sensor, like the throttle position sensor.

Anyone have an educated guess on how I can fix this myself without taking it into a dealership and hooking it up to their computers?

Is this a new thing that didn't happend before, or is the car new to you? If this is a new thing, then something is wrong. If the car is new to you, then it's the traction control going weird due to your launch style. Try turning off the DSC and see if things mellow out.

Even though my Z3 and 330CI has the same engine, they require very different launch techniques. If I try to drive the Z3 like the 330, it bucks in 1st gear.

When is slow or heavy traffic, I turn off the traction control because it messes me up.

[RyanOaks328i]

I've owned the car 5 years. This is a new thing that is worse on hot summer days than it is on cold winter days (although it can occur on either). When the 'bucking' or 'jerking' occurs, the clutch is completely engaged. It'll occur in any gear. The common factor is trying to accelerate from low RPM. I'd expect a smooth acceleration.

[mach460]

Is it like an engine miss? I am having the same problem with my sons 323i with 117000 on it we replaced the spark plus about a year ago with bosch platuim 4 I am thinking maybe a coil wire or coil pack,what do you guy's think?

[bleepstreet]

Definitely sounds like a fuel filter to me.

[RyanOaks328i]

It is like a miss, but like all the plugs are missing at the same time, not just one cylinder. Plugs were replaced at ~100K with bosch platuim 4. Wires and coil packs are still origional.

[RyanOaks328i]

If it was s fuel filter, why would it just cut out at low RPM acceleration, and not during high RPM?

[Smilez]

It is like a miss, but like all the plugs are missing at the same time, not just one cylinder. Plugs were replaced at ~100K with bosch platuim 4. Wires and coil packs are still origional.

i foudn your problem bosch platinum spark plugs, many have had issues with those. Get oem ones that should do it and replace your fuel filter.

[mach460]

Iput new plug connectors on and no good I have a code p0301 I cleared it and drove it checked it agin and got the same code ,,,,any one know what that code is?

[robonline21]

Fuel filters are cheap. I'd try that and see if it fixes the prob. May work fine at higher RPM because the fuel pump is pulling harder. my 2 cents

[mach460]

I just bought one and going out to put it on now ,I will let ya know how it works out thanks.....................

[N8s 330xi]

I gotta back the Fuel Filter, just because of the low RPM thing.
If you have a blockage on your fuel, higher pressure would sometimes be able to help push that blockage out of the way for a while, compensating for the restriction. When you are driving slow and doing low RPMs, the fuel pressure isn't enough to push the blockage out of the way.
I think the only other possibility would be air. I could see how a crack in the intake would cause the Mass air flow sensor to maladjust the mixture at low RPMs, but at high RPMs, you may have enough air going through to compensate.

*Not a mechanic, but it all seems logical to me...

[mach460]

not the fuel filter just put new one on stiil the same.
I found out code p0301 is the # one cyl. has a miss in it so I replaced the plug and wire and still the same,thay were the cheapest to do so now I guess the coil pac...................

[mach460]

OK I took the coil pac out of #one and put it in #two cyl.took it for a ride eng light came back on put the scanner on and it read p0302 witch mean #two cyl. has a miss in it and thats were I put the coil pac.
so I went and bought a new pac and put it in #two cyl. and it runs like a champ no more bucking on take off nice and smooth,,,so there ya go might want to give that a try.........

[RyanOaks328i]

Thanks for all the suggestions. I'm going to be busy for the next few weeks, but I have some things to try now.

[RyanOaks328i]

Replaced the spark plugs, no success. Took it to a mechanic and the computer wasn't throwing any code. The mechanic sold me a new coil and told me to start swaping out the coils until the car runs better. On the 5th coil (second from the rear) the car started running perfectly. The car likely missed at higher RPMs, but it wasn't noticable.

Nope, I didn't change the fuel filter.

[earache]

I have a 2004 M3 SMG which had a severe case of jerky acceleration coming off the line. The car would buck severely. It did not have any codes until the other day when it threw a p0173 and a p0174. I went to check out the MAF and my intake boot had come loose from the intake manifold. Put the boot back on and tightened it down. Problem solved. May need to check for vacuum leaks and your MAF if it is not in the firing or the pump pressure.

[rjsquire]

Replaced the spark plugs, no success. Took it to a mechanic and the computer wasn't throwing any code. The mechanic sold me a new coil and told me to start swaping out the coils until the car runs better. On the 5th coil (second from the rear) the car started running perfectly. The car likely missed at higher RPMs, but it wasn't noticable.

Nope, I didn't change the fuel filter.

Thanks for this post.

I'm experiencing the same thing, also more on warm days. Doesn't seem to be related to engine temperature. I notice it more in higher gears, where I'm turning low RPMs for longer periods of time. Where you would expect the engine to lug from loading it up in too high a gear, instead it jerks. almost feels like hitting a puddle (kinda, not exactly). I rarely floor the car, and just press the gas pedal enough to keep the revs rising. I've noticed that when I get the bucking, if I press the gas harder it smooths out.

I'm getting no dash lights, so it wouldn't surprise me at all if there are no codes being thrown.

Now I'm tempted to try that coil solution, but what a pain! Lots of test driving to isolate the problem.