[PKinsella]

Hey guys, I did some searching and decided that maybe I'm the only one with this issue, but hopefully someone can give me some pointers:

My car is an 09 335i 6mt e92, and right now I'm running a JB4 G5 ISO on map 5, but I had the same issue (though not as pronounced, and easier to control) when I was stock.

This happens in 1st OR 2nd gear depending on my speed. Basically, just as in any manual car, I give it a little gas, then slowly let out the clutch. While I'm accelerating at a slow pace, if I'm not EXTREMELY careful, the car will faintly start jerking, then it will very quickly magnify itself to the point that I either have to mash the throttle or push in the clutch to stop it.

Now, I know what's happening: I give it a little gas, my body presses back in the seat, which makes me let off the gas, which lets my body move forward slightly, pressing the gas again. This happens in rapid succession and magnifies itself just like harmonic motion.

I know the mechanics of it, but why am I having issues with it on this car and I've never had the issue before?? Is the throttle too sensitive??

Any ideas would be appreciated, as it can be just outright embarrassing when it happens, not to mention it's annoying that I have to baby it so much.

[hetzle]

You might just not be used to the power/torque of the car (6MT driver here too), I had a similar issue with my old E39 M5 in Sport Mode (throttle becomes too responsive and results in your foot bouncing off the pedal as you try to let off). I haven't experienced this issue with this car, but I did have plenty of practice on the M5, which had a legitimately sensitive throttle

[PKinsella]

Originally Posted by hetzle

You might just not be used to the power/torque of the car (6MT driver here too), I had a similar issue with my old E39 M5 in Sport Mode (throttle becomes too responsive and results in your foot bouncing off the pedal as you try to let off). I haven't experienced this issue with this car, but I did have plenty of practice on the M5, which had a legitimately sensitive throttle

I would be inclined to agree, but I didn't have this issue with either of my previous two cars, both of which made more power than this one (Evo IX, then LS3 Corvette).

SO frustrating!

[hetzle]

Originally Posted by PKinsella

I would be inclined to agree, but I didn't have this issue with either of my previous two cars, both of which made more power than this one (Evo IX, then LS3 Corvette).

SO frustrating!

It's possible the throttle of this car is more sensitive than the other two I guess just practice at it, I eventually got it down after a few months

[DJJimGreen]

You know, I've thought the same thing and had an extremely crazy Evo in my past too. I was wondering if it could have been an ignition problem, but no codes are thrown so I just figured it was a really weird tuning curve when in 1st or 2nd gear. Slow speeds I seem to blip around.. Actually kind of relieved to see someone else explaining this phenomenon.

[drjekl]

Remove the CDV for a smoother takeoff, but it sounds like its more then this?

[ashmostro]

Adjusting your wastegate default position, and duty cycle helps with this over-sensitivity. The newest versions of the firmware allow you to adjust both through the steering wheel controls. Have you tried this?

[PKinsella]

Originally Posted by ashmostro

Adjusting your wastegate default position, and duty cycle helps with this over-sensitivity. The newest versions of the firmware allow you to adjust both through the steering wheel controls. Have you tried this?

This is exactly what I just did and I'm trying it out. It was at 70 and I moved it down to 60. I haven't had enough of a chance to try it yet, but I will report back.

And drjekl, I know that removing the CDV would help things. I'm going to look into doing that, as I haven't liked it from the beginning.

[ashmostro]

The menu 12 feature (duty cycle) will make an even bigger difference to the jerkiness. Try a setting of 25 on the tacho.

[Ch3ss]

have you tried resetting adaptations?

[tcw]

For when I used to have this problem, I was able to fix it by cleaning the intake valves.

[HGreen335]

have this same thing and its definitely not a sensitive pedal or CDV problem. I dont get it if I accelerate aggressively but when im driving away from a light slowly in moderate traffic it happens every time. Its incredibly annoying. Im also JB4 G5 ISO

[Rotorocious]

Originally Posted by ashmostro

Adjusting your wastegate default position, and duty cycle helps with this over-sensitivity. The newest versions of the firmware allow you to adjust both through the steering wheel controls. Have you tried this?

+1 for this

[3000GT MR]

When i first got my car i had the same issue. I know exactly what you described. Spark plugs solved it for me. Mine would only do it on cold starts. After it was warm it wouldn't. Worth the shot if you haven't changed them

[2jzn54]

i have the same issue as the OP and have messed around quite a bit with the wgdc and wg default position settings as well as open loop fueling.. ive been able to limit most of the jerkiness, but not eradicate it completely.

The jerkiness also happens at partial throttle while cruising in higher gears as well. e.g. while sitting at 45 mph in 6th and giving a little gas to pass someone

Spark plugs should not be the issue for me.. I recently replaced them with the recommended one step colder NGKs.. Only potential issue I see is that one of the plugs could be gapped incorrectly.

I will likely send a log to Terry, but since it doesn't happen most times even in these specified conditions it can be difficult to capture.

[blackbeast06]

I think it is just because the cars have so much torque down low. Sometimes if you don't come off the clutch correctly it happens. Every once and a while it happens to me and has also happened in a V8 mustang with a lot of torque.

[2jzn54]

Originally Posted by blackbeast06

I think it is just because the cars have so much torque down low. Sometimes if you don't come off the clutch correctly it happens. Every once and a while it happens to me and has also happened in a V8 mustang with a lot of torque.

this isn't just limited to taking off.. my issues are mainly when i'm already engaged in a gear and moving

[PKinsella]

Well, it seems to be quite a bit better, and all I changed was the wastegate default position. Jury is still out though.

And I'm sorry, but I wouldn't describe this car as "torquey" down low... but maybe that's just because I had a 430hp 410ft-lb V8 under the hood a couple months ago...

[3000GT MR]

Originally Posted by Daily Three

i have the same issue as the OP and have messed around quite a bit with the wgdc and wg default position settings as well as open loop fueling.. ive been able to limit most of the jerkiness, but not eradicate it completely.

The jerkiness also happens at partial throttle while cruising in higher gears as well. e.g. while sitting at 45 mph in 6th and giving a little gas to pass someone

Spark plugs should not be the issue for me.. I recently replaced them with the recommended one step colder NGKs.. Only potential issue I see is that one of the plugs could be gapped incorrectly.

I will likely send a log to Terry, but since it doesn't happen most times even in these specified conditions it can be difficult to capture.

To big of a gap will do the same as described by OP. I just went through this scenario again when i was testing spark plug gaps with the ngk's. Did you gap them at all?

[2jzn54]

Originally Posted by PKinsella

Well, it seems to be quite a bit better, and all I changed was the wastegate default position. Jury is still out though.

And I'm sorry, but I wouldn't describe this car as "torquey" down low... but maybe that's just because I had a 430hp 410ft-lb V8 under the hood a couple months ago...

with the jb4 alone you are probably sitting right at or above 410 ft lbs of tq..

[2jzn54]

Originally Posted by 3000GT MR

To big of a gap will do the same as described by OP. I just went through this scenario again when i was testing spark plug gaps with the ngk's. Did you gap them at all?

gapped them to recommended spec drove and checked them twice.. if i didn't gap them at all i can assure you the car would drive and sound like a big heap of misfiring crap and the car would barely put down enough power to get moving lol.

nonetheless i'll probably check the gap on each again this weekend and see if i can find any inconsistencies.

[PKinsella]

Originally Posted by Daily Three

with the jb4 alone you are probably sitting right at or above 410 ft lbs of tq..

I would like to have what you're smokin', sir, haha.