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

[pnvhome]

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

You need new fuel injectors, i have absolutely the same problem https://youtu.be/R9xWLTlaLns
Try everything in soft, but problem is in injectors, also you can have problem that after 5-15 minutes on hot it start engine not as fast as on cold motor.
I set new injectors, load stock CSL program with modification for stock m3 cams, and now it is absolutely smooth

[Arith2]

This is the best explanation of this problem that I have seen. I didn’t realize the CSL airbox was designed to operate above 3k rpms Thank you.

It's no problem. Here's a few videos.

(42) How Porsche Perfected Intake Manifolds - YouTube

(42) Best Intake Runner Shootout - Velocity stacks - Trumpets - Dyno tested on ITB's - 200whp 4AGE - YouTube

(42) The Most Powerful V8 Engine Ever (Naturally Aspirated) - 2023 Corvette Z06 - YouTube

You can obviously go read some actually scientific papers on the whole effect but most people aren't that nerdy or interested in airflow specifically.

[Slideways]

It's almost always a tuning issue. With the PCS CSL tune, you can floor it in fourth gear at 2000 rpm and the motor will pull smoothly all the way to redline. Having that bucking issue is unacceptable and drivability should be the same as with the stock airbox. If the car in stock form did not have the bucking issue, it should not have it with the CSL setup. If it did that even slightly, there is a hardware issue.

Here is a car with a CSL airbox, 288/280 cams being floored in 6th gear at 1800 rpm:

[duracellttu]

Helmholtz resonance happens in the intake and it the pressure waves are hitting the valves when they open. It isn't a lack of air in the intake but a lack of negative pressure in the ports to pull the air in. This is never going to be a tuning issue. A tune can cut fuel to avoid violent bucking but you should understand what you are driving. The intake is designed to function above 3000rpm. If you lower the bottom ideal rpm function, you lower the top end. The same issue would occur at high rpms if the intake was designed for 1000rpm WOT. NO engine should be floored at 1800rpm except engines specifically designed to function well in that range. If you are flooring your car below 3000 rpm, stop.

This is the best explanation of this problem that I have seen. I didn’t realize the CSL airbox was designed to operate above 3k rpms Thank you.

[Arith2]

Helmholtz resonance happens in the intake and it the pressure waves are hitting the valves when they open. It isn't a lack of air in the intake but a lack of negative pressure in the ports to pull the air in. This is never going to be a tuning issue. A tune can cut fuel to avoid violent bucking but you should understand what you are driving. The intake is designed to function above 3000rpm. If you lower the bottom ideal rpm function, you lower the top end. The same issue would occur at high rpms if the intake was designed for 1000rpm WOT. NO engine should be floored at 1800rpm except engines specifically designed to function well in that range. If you are flooring your car below 3000 rpm, stop.

[Cubieman]

Yeah I'm not quite sure how it'd relate either. Well the little female and male crimp pins I have in my hobby kit don't fit the harness for the m3, so I can't test this theory anyways. Just something to keep in mind when I bring it to get looked at I guess.
When you say you'd de pin 17 for ground can you elaborate? I thought you mentioned that ground gets used for the iat Turner harness

If you are not using the Turner harness I would de-pin pin 17 as it not being used. If you are using the Turner harness I would use pin 16.

I suppose using the same ground for both MAP and IAT via Turner harness wouldn't hurt, but I'm not 100% on that.

[M3llowM3]

Possibly, but I would not have it spliced into pin 17 for ground I would de-pin 17 (MAF ground I do believe).
If you are using the Turner IAT relocation harness I think it using pin 17 for ground, I use the Turner harness and that is why I used pin 16 for ground.

How these would relate to strange camshaft sensor readings I don't know, seems like you may have separate issue going on.

Yeah I'm not quite sure how it'd relate either. Well the little female and male crimp pins I have in my hobby kit don't fit the harness for the m3, so I can't test this theory anyways. Just something to keep in mind when I bring it to get looked at I guess.
When you say you'd de pin 17 for ground can you elaborate? I thought you mentioned that ground gets used for the iat Turner harness

[Cubieman]

So I had a thread where I was getting weird camshaft sensor readings and check engine lights after installing my Turner airbox with a kassel modded ecu.
https://nam3forum.com/forums/forum/m...15-p0010-p0185
I still haven't solved my issues as the car is in storage, but just skimming this thread made me go check my wiring in the map and I am using pin 17 for my ground, not 16. I am also using the Turner iat harness. Could this possibly be my issue? Is it worth going back and putting the ground into the empty space in pin 16 vs being spliced into wire on pin 17?

Possibly, but I would not have it spliced into pin 17 for ground I would de-pin 17 (MAF ground I do believe).
If you are using the Turner IAT relocation harness I think it using pin 17 for ground, I use the Turner harness and that is why I used pin 16 for ground.

How these would relate to strange camshaft sensor readings I don't know, seems like you may have separate issue going on.

[M3llowM3]

Ok, so that sounds good, I used the same pins for MAP. There was one member, jbfrancis3 who used pin 16 as IAT ground and had some erratic readings if I recall correctly but I think the consensus was pin 16 is a suitable ground for MAP/IAT.

You can use testo and see the Kassel MAP adapter voltage going up/down up/down etc. during idle as it's positioned in a TB whereas the the voltage of a MAP sensor adapter that ties into the brake boost line is smooth steady line at idle.
But once you press the gas and get the car up to ~1200RPM the Kassel MAP location's voltage smooths out so I don't think that is the issue, just food for thought. You might try the MAP adapter from member COVID-19 is all else fails.
What I just types might not be very coherent as I'm a few drinks in but I made a thread a while back in regards to this, which is likely a non-issue.

So I had a thread where I was getting weird camshaft sensor readings and check engine lights after installing my Turner airbox with a kassel modded ecu.
https://nam3forum.com/forums/forum/m...15-p0010-p0185
I still haven't solved my issues as the car is in storage, but just skimming this thread made me go check my wiring in the map and I am using pin 17 for my ground, not 16. I am also using the Turner iat harness. Could this possibly be my issue? Is it worth going back and putting the ground into the empty space in pin 16 vs being spliced into wire on pin 17?

[lvm3sm46]

Thanks for reporting back

[e36addict]

I finally got around to some remote tuning with Hassan and my issue is resolved. Still some slight hesitation around 1800rpm, but the bucking is gone. One day I'll get around to doing some actual remote dyno tuning. Sorry to bump an old thread, but I wanted to thank you guys for referring me to him!

[pnvhome]

I made a little video to show what was the problem, without cats, now with cats car works perfectly, no any such problems, on csl intake from turners

https://youtu.be/R9xWLTlaLns

[fattycharged]

I was always unsure how people described this as “jerky” in the past, you hit the nail on the head with “bucking bronco” as that is EXACTLY what it is like. Scary movement, feels like it’s trying to rip itself apart.

This is fantastic news. Mine does the same and boy is it terrible to drive that way, especially coming from a dead stop.

Thanks for the update.

[BMWahba]

Had the same issue on turner intake when use SS section 1 without cat, and made off second O2 sensors via ECUWorx app, Hassan tried to fix that, but I don’t have access to afr sensor in my city, so the only way to fix for me, a back to euro cat section 1, section 2 is SS X pipe, and stock csl tune with edited value of cams to stock m3, now there is no any problems even on 4 gear and 1600rpm with full throttle, but that is not ok for engine

Interesting data point! I do believe it had something to do with my section 1 pipe.

[Tonggi]

dang that intake sounds so good!