Experts Help - CSL Airbox - Violent Jerkiness and Bucking Under 2k RPM Under Load

[heinzboehmer]

Huh. Interesting. I am trying to do it sure, but really in normal city driving I am often under 2k RPM and roll into throttle. This makes the car almost undrivable, let alone how violet it feels, the car feels like it wants to explode.

Yeah on mine I would have to purposefully try to get it to do it. Definitely wouldn't happen under normal driving conditions, like when rolling into the throttle from below 2k rpm.

Have you made sure your IAT and MAP are working correctly? You also said swapping in your stock DME yields the same result, so are you sure you're running CSL software on the other one?

[Slideways]

My vanos is freshly rebuilt with a unit from ATS///Antone so I really cannot imagine this to be a failure but I guess it is something to consider. I got all new parts including the solenoid and pressure regulator....

I need to try a stock section 1. What is really eye-opening is that the behavior is consistent no matter the tune, or the DME even. Map sensor plugged or not. So, clearly either something mechanical or isolated to the vehicle system somewhere.

Did you perform a VANOS test? Rebuilding the VANOS did not solve his issue, only a completely new unit from BMW. For these exchange services, it would be really nice to get your original unit back rebuilt, not another one from another car (just to eliminate variables).

[BMWahba]

That shaking is really harsh, definitely seems like it's some piece of hardware failing.

Yes indeed. But what. TPS? Vanos is fresh. Something in the motor? The shaking and bucking, at least what we think so far, is caused by an air/fuel issue. But I'm not really ruling anything out until I know for sure, and so we definitely need to get an AFR gauge on it to see what is happening...

[BMWahba]

My car would do that with the stock CSL tune if I really really tried to bog the engine (i e. 100% throttle under 2k rpm in fifth/sixth gear). Doesn't do it anymore with my PCS tune.

Huh. Interesting. I am trying to do it sure, but really in normal city driving I am often under 2k RPM and roll into throttle. This makes the car almost undrivable, let alone how violet it feels, the car feels like it wants to explode.

[EthanolTurbo]

That shaking is really harsh, definitely seems like it's some piece of hardware failing.

[BMWahba]

Running too rich is my guess based on this video:

I believe he said it was the VANOS response time and a new VANOS unit solved the issue. I'd like to think one of the parts that came with the new VANOS unit fixed the issue like the pressure regulator or valve body, but he insisted it needed a completely new VANOS.

Probably worth checking the VANOS response times with DIS. Stock section 1 would be good as well, but that is what the owner in the video was running.

It definitely should not do that. When it is working properly, it can be floored it from idle and it should pull without hesitation.

My vanos is freshly rebuilt with a unit from ATS///Antone so I really cannot imagine this to be a failure but I guess it is something to consider. I got all new parts including the solenoid and pressure regulator....

The video you shared is basically exactly what mine feels/looks/sounds like.

I need to try a stock section 1. What is really eye-opening is that the behavior is consistent no matter the tune, or the DME even. Map sensor plugged or not. So, clearly either something mechanical or isolated to the vehicle system somewhere.

[heinzboehmer]

My car would do that with the stock CSL tune if I really really tried to bog the engine (i e. 100% throttle under 2k rpm in fifth/sixth gear). Doesn't do it anymore with my PCS tune.

[Slideways]

Running too rich is my guess based on this video:

I believe he said it was the VANOS response time and a new VANOS unit solved the issue. I'd like to think one of the parts that came with the new VANOS unit fixed the issue like the pressure regulator or valve body, but he insisted it needed a completely new VANOS.

Probably worth checking the VANOS response times with DIS. Stock section 1 would be good as well, but that is what the owner in the video was running.

It definitely should not do that. When it is working properly, it can be floored from idle and it should pull without hesitation.

[BMWahba]

I wouldn't get too upset man these things happen. You'll soon figure it out and be a happy camper though I know how frustrating these like this can initially be.

I wonder if it could be a tps going out and exacerbated by airbox install.

Definitely trying to stay positive! I had this airbox sitting in the shelf for about 8 months, so not the glorious and smooth install I was hoping for.

This is an interesting point and honestly I didn’t think of this. I don’t have codes, (well I did on the old DME because it wasn’t tuned for the headers and lack of 02s) and I was under the impression they throw a code and put you in limp mode as soon as it detects fault. Can someone confirm?

[jet_dogg]

I wouldn't get too upset man these things happen. You'll soon figure it out and be a happy camper though I know how frustrating these like this can initially be.

I wonder if it could be a tps going out and exacerbated by airbox install.

[BMWahba]

Well, no matter how much research I did prior to installing this CSL intake, I have come across a problem that I have not read nor seen anything about. So, I am posting this for reference in case anyone else comes across this issue in the future. Any input from those who have experience is appreciated.

And I will preface this by suggesting, the problem I am about to describe is not the typical CSL hesitation issue. This is a violent jerkiness that shakes the entire car and bucks like a wild bronco. Not good. Here's the video:

https://youtu.be/I8smFkWFz0k

So here is the situation:

I installed a Karbonius CSL intake yesterday and along with it I dropped in a new HP DME from Kassel. They set it up with the base map CSL tune alongside a few adjustments for my car. Install went good, simple, no issues.

The setup on the car is as follows:

CSL Airbox running Map Sensor and Turner IAT (US Spec IAT scaling)
Euro Headers
CPI Rasp Pipe Section 1 (with crossover) *Hassan from HTE did mention that this could affect AFR's and cause this to be happening.** I need to get hands on a stock section 1 to try it.
Stock Section 2
SGT Scza Muffler
EGT Delete, No Post-Cat 02's.

Essentially, if I am under 2k RPM, in either 2nd, 3rd, 4th, and roll on throttle, either partially or WOT, the car jerks violently, and stutters until it basically get to 2100RPM and from there she sings. So, for normal everyday driving the car runs like absolute garbage.

Before potentially realizing I had the issue, I wanted Hassan to tune the car so first thing I did was tune it today remotely. After getting the tune setup, I went for a drive and noticed the issue when doing pulls under 2k RPM. I only drove on the Kassel tune for like 2 miles, so I can't say for sure if it did it before, I didnt try too many low rpm throttle roll from below 2k rpm before today, so I don't know if something changed from install to today. But regardless something is up.

So Hassan (thanks again for all the help dude) walked me through and we ruled out a few things so we did the following:

- Flashed back to the Kassel Tune and it still had the same jerkiness.

- Unplugged the map sensor to isolate it as the problem, same issue

- Unplugged the 02s to isolate them as the issue - same problem

- Unplugged the old DME, swapped in my stock DME ---- SAME ISSUE!

So clearly, something is up with the car. I was hoping it was the DME that I had Kassel convert but unfortunately, that is not the case.

I realize that the only way we can really see what is going on is to get an AFR gauge on the car or on the dyno to see what's going on, but even with the way it's running now below 2k rpm I don't really even want to dyno it. I plan to tear the airbox apart and uninstall it, retracing my steps to see what if anything got loose, or went wrong.
But in the meantime, I needed this thread to exist to maybe hear if anyone else had this or a similar issue, or if anyone can chime in to what potentially things I can look into to get my car running properly.

This freaking blows!
TIA and Happy 4th