Catless X-Pipe Misfire/Torque Dip/Bog [SOLVED?]

[SYT_Shadow]

Originally Posted by MikeYQM

Well that and so far your AA and Evolve valve open are problem free too. I think you're one of the few who have experienced both problem and problem free cars.

Both of mine have been fine and with multiple tunes as well. But I've driven a problematic car and until I felt it I thought the owner was complaining about nothing.

[MShift]

I spoke to Randy from EPIC via e-mail and he said that he does in fact have a tune adjustment specifically for the BW x pipe that gets rid of bottom end issues. It may solve the issue, but I still think its a physical egineering problem and the tune is is more of a fix than something to be too excited about. I am going to go get dynoed before and after the tune to see what happens, but I'm not planning to do it for another 2-3 weeks.

[V8Juice]

I feel relieved to have stumbled upon this thread, my mechanic thinks it might be my coil packs since we just changed out plugs but ive felt I had the issue ever since I installed my exhaust.

BW catless X pipe
Valvetronic Rear
Alpine Stage 2?

[MikeYQM]

Originally Posted by V8Juice

I feel relieved to have stumbled upon this thread, my mechanic thinks it might be my coil packs since we just changed out plugs but ive felt I had the issue ever since I installed my exhaust.

BW catless X pipe
Valvetronic Rear
Alpine Stage 2?

Does the problem occur with valves open and closed?

[MikeYQM]

Originally Posted by MShift

I spoke to Randy from EPIC via e-mail and he said that he does in fact have a tune adjustment specifically for the BW x pipe that gets rid of bottom end issues. It may solve the issue, but I still think its a physical egineering problem and the tune is is more of a fix than something to be too excited about. I am going to go get dynoed before and after the tune to see what happens, but I'm not planning to do it for another 2-3 weeks.

From what I have gathered, I don't think there is a fault with any individual component, but rather a compatibility issue between various mids, rears and tunes.

[V8Juice]

Originally Posted by MikeYQM

Does the problem occur with valves open and closed?

Open since I rarely drive with them closed. Closed is for cold starts in the morning so my neighbors wont hate me

[dmlf]

Originally Posted by V8Juice

I feel relieved to have stumbled upon this thread, my mechanic thinks it might be my coil packs since we just changed out plugs but ive felt I had the issue ever since I installed my exhaust.

BW catless X pipe
Valvetronic Rear
Alpine Stage 2?

I just changed all 8 injectors and 8 coils ( USD 2500 yay ), plugs are 8000kms old, I get less jerkiness but I can stil reproduce the issue . One symptom that I didn't had before is missfires, mainly on 5,6,7,8 + one or more from [1..4]

Next step is replacing the plugs, then checking wiring harness then trying another ECU ( maybe a coil driver issue ).

[MikeYQM]

I was able to pull some data logs this morning. I think they show the problem pretty well.

In first photo you can see 3 successive pulls from 2000-3000 RPM. You can see the Lambda dip, then STFT shits the bed then they start chasing each other in gradually improving cycles.

In the second photo, there are 3 pulls through the 2500-3000 rpm range. #1 & #2 replicate what is seen in the first photo. In # 3, a normal pull in the same range, STFT increases contrary to the problem pulls.

In the 3rd photo, this is a severe example where the RPM really hung due to the problem, with a couple more less severe pulls.

In the 4th photo, this is another severe example.

[alfalfa]

In my opinion you can see a X-Pipe scavenging effect and the software doesn´t fit to this.

As in the first post stated adaptions may help but the ecu can just adapt in specific ranges.
I think this effect here can be reduced with proper vanos mapping in this range.

[MikeYQM]

Update from today with new file from Alex:

[MikeYQM]

Data from same time period.

[tdott]

Can you show throttle or tps on those graphs? otherwise it's hard to tell what is happening.

[MikeYQM]

Originally Posted by tdott

Can you show throttle or tps on those graphs? otherwise it's hard to tell what is happening.

I don't think the OBD I'm using produces throttle data, I'd have to create a custom PID. If you look at the gradual RPM increases from 2500-3000 or so, that's about 30-50% throttle input from my foot feeling.

[CurbBender'90]

Well I have had my BW x-pipe for a few months and noticed this condition ironically when my TA's were going bad so it never really dawned on me it could have been the pipe. One day I went to go race a scat pack, I floored it and the car fell flat on it's face like I was late to shift, then the power came full on after 3k...so of course I lost! Seems like the longer the BW pipe stays on the adaptions to it become worse because now anytime at part throttle in the 2k-3k rpm range it stutters until above that. I have never had any problems above those rpms that I have noticed. Also within the last 2 weeks I installed new 02 sensors[primary], new gaskets and a Eisenmann Sport and the car sounds GREAT, I MEAN REALLY GOOD! The issue is STILL there so a axleback will not change this issue nor will a tune I believe... I think it's a exhaust flow issue to be honest because with a stage 2 test pipe setup I have NEVER had the car behave this way in my 7 years of owning it...check these vids out

This is the RPM stutter I'm describing..

Trying to Floor it with DSC off

Trying to Floor it with MDM Mode

Notice how the tires won't even break traction even with DSC off at full throttle, you usually can, but the power irruption won't let me....

[V8Juice]

So the Bimmerworld Xpipe is the problem or the fact that its a forward facing xpipe?

[MikeYQM]

Originally Posted by V8Juice

So the Bimmerworld Xpipe is the problem or the fact that its a forward facing xpipe?

Seems common on all the forward biased X-Pipes. It's doesn't seem common enough to call it a flaw though, many people seem to have no problem. I believe it's an issue of compatibility.

[Spoff_E90_M3]

Originally Posted by MikeYQM

- X-Pipe Type:
- Axle Back Exhaust Type:
- Tune:

Same issues with it bogging like CurbBenders first video above. I see it is also in D6 with the issue as well. If I drop a gear or two using the paddles it is fine.
Bimmerworld X-pipe no cats with resonators
Stock exhaust
Alpine 93 stage 2 tune

[M43S7RO]

Wow, that's pretty bad, did you ever change out the TAs?


[/B]

Originally Posted by CurbBender'90

Well I have had my BW x-pipe for a few months and noticed this condition ironically when my TA's were going bad so it never really dawned on me it could have been the pipe. One day I went to go race a scat pack, I floored it and the car fell flat on it's face like I was late to shift, then the power came full on after 3k...so of course I lost! Seems like the longer the BW pipe stays on the adaptions to it become worse because now anytime at part throttle in the 2k-3k rpm range it stutters until above that. I have never had any problems above those rpms that I have noticed. Also within the last 2 weeks I installed new 02 sensors[primary], new gaskets and a Eisenmann Sport and the car sounds GREAT, I MEAN REALLY GOOD! The issue is STILL there so a axleback will not change this issue nor will a tune I believe... I think it's a exhaust flow issue to be honest because with a stage 2 test pipe setup I have NEVER had the car behave this way in my 7 years of owning it...check these vids out

This is the RPM stutter I'm describing..

Trying to Floor it with DSC off

Trying to Floor it with MDM Mode

Notice how the tires won't even break traction even with DSC off at full throttle, you usually can, but the power irruption won't let me....

[Spoff_E90_M3]

I went out for a drive last night and noticed that for me it is a gearing and RPM (2 - 3k) issue once driving:
2nd, 3rd, 4th - all okay. No hesitation
5th, 6th, 7th - definite hesitation. It’s like the car doesn’t know what it needs to do. Won’t accelerate and it won’t drop a gear even with pushing down the pedal more. Eventually the computer figures it out and drops 1 or 2 gears and starts going.

If over 3k rpm it does fine. So at the track it will do great. Around town it sucks.

[CurbBender'90]

Originally Posted by M43S7RO

Wow, that's pretty bad, did you ever change out the TAs?


[/B]

Yes I did change them, this is after the change...it was soo bad I swore my mechanic didn't swap them but I got my older ones and opened them so I know it was originally BMW.

[SYT_Shadow]

Update: we put the Bimmerworld street muffler on a Alpine car with the Bimmerworld xpipe with HFCs which has had this issue for a long time.

There is zero difference with the Bimmerworld muffler vs before with the OEM '2 pipe method' exhaust.

[tdott]

Originally Posted by SYT_Shadow

Update: we put the Bimmerworld street muffler on a Alpine car with the Bimmerworld xpipe with HFCs which has had this issue for a long time.

There is zero difference with the Bimmerworld muffler vs before with the OEM '2 pipe method' exhaust.

I wonder if clearing adaptations would yield anything different.