Pulsing when Accelerating

[carma143]

When fully stopped, if I quickly apply gas at about 3/4 of WOT or more, the engine "pulses" and won't stop until I let go of the throttle and slowly reapply. it's fairly embarrasing at an intersecrion, seeing my car move slightly back and forth on its suspension while slowly moving foreward (~5 mph).

I have tried looking up solutions to this issue, and some belive that the ECU may be faulty, the fuel injection may be faulty, certain wires are "dirty", or that unbalanced tires are at fault.

There is a very low probability that the tires are the issue because this also occured before I stepped up to stickier SummerTires.

I have had this issue since I bought the car, but originally thought it was just me being very bad at driving a manual, and then later believing it was the 87 octane gas I was using.

Any insight is appreciated.

Edit: I drive a manual

[blue cat]

Auto?

[Decay107]

Does the TC light come on on the dash?
Are you still using 87? (also why 87?!?)
What RPMs? (Wouldn't happen to be ~3000-4200 right?)
Does it continue through redline?

[Fastbrew]

Has someone changed the clutch?

[Black Tire]

My first guess would be the traction control, especially if your car has an automatic transmission.

[otterpop]

I also happen to get this randomly though from a stop to a go. it usually happens right off the bat around 2K rpm + and doesn't stop until I shift. It doesn't happen all the time, only happens rarely. I have never seen any lights come on and I have never really noticed it hurting the car in anyway. Maybe i'm just bad at a manual.

[N1rve]

If 3/4 or WOT makes your car move slowly through an intersection...I think you got bigger problems.

[carma143]

The TC light does not turn on. This occurs even when I have pressed the center button for ~5 seconds "mostly" turning off TC and Stability.

I stopped using 87 octane several months ago. I used about 2.5 tanks of it before I switched (1 is assumed from dealer when bought).

The clutched has not been changed while in my posession.

I'll have to check tomorrow what rpms the car stays at when this happens. this issue is very easily repeatable (not happening "randomly").

Edit: Could it be a faulty spark plug?

Taken from a BMW Forum:

"Anyway, what they ended up doing was replace an ignition coil because the retainer was not holding the coil on the plug. Whatever code was being thrown was indicating a misfire on cylinder 3, as even someone as non-mechanical as myself thought."

[carma143]

Originally Posted by Decay107

Does the TC light come on on the dash?
Are you still using 87? (also why 87?!?)
What RPMs? (Wouldn't happen to be ~3000-4200 right?)
Does it continue through redline?

When this occurs, there is no meaningful acceleration, a.k.a. stays at around 5 mph no matter how far down I press down the pedal. Feathering the gas (allowing the car to move slowly), then WOT typically does not result in this bog.

[Decay107]

Originally Posted by carma143

The TC light does not turn on. This occurs even when I have pressed the center button for ~5 seconds "mostly" turning off TC and Stability.

I stopped using 87 octane several months ago. I used about 2.5 tanks of it before I switched (1 is assumed from dealer when bought).

The clutched has not been changed while in my posession.

I'll have to check tomorrow what rpms the car stays at when this happens. this issue is very easily repeatable (not happening "randomly").

Edit: Could it be a faulty spark plug?

Taken from a BMW Forum:

"Anyway, what they ended up doing was replace an ignition coil because the retainer was not holding the coil on the plug. Whatever code was being thrown was indicating a misfire on cylinder 3, as even someone as non-mechanical as myself thought."

If you don't have a code, the engine probably isn't misfiring. Any chance for a video?

[CokeSlap]

My money is on the traction control. It has been a real pain during the cold days in Nebraska with just a light dusting on the ground.

[carma143]

Originally Posted by Decay107

If you don't have a code, the engine probably isn't misfiring. Any chance for a video?

I have a friend with a GoPro. I'll see if I can borrow it for half an hour or so.

Just so we are clear, the BMW from the forum was sending out a code indicating a misfire even though there was none, shutting off a functioning valve "valve 3" for a fraction of a second, continuously, causing a large jerk with the coninuous loss and gain of the valve's power. The jerking I get is pretty violent, but I don't hear any out of the ordinary sounds occuring.

[kodyo]

I think I know what you are referring to and I'm pretty sure it's the syncros in the transmission getting everything up to speed. When it begins to surge on mine, I can accelerate out of it though. Experiment with letting out the clutch and modulating the gas differently. Have you changed trams fluid yet?

[celica73]

Wheel hop?