Low RPM misfire ESS xpipe

[SYT_Shadow]

Originally Posted by strokemycocktus

The only thing that is completely weird for me is that it occurs always and only at 2500 rpm. Not at idle, not at redline, not anywhere else in the rev range.

Exactly the same thing that happens to audioslave... his car actually dynos really well

I'm running an off the shelf, canned tune on my E92 and so is the other guy with the ESS tune on his BW xpipe. For sure this is a topic to explore more in depth

[tdott]

Originally Posted by SYT_Shadow

Exactly the same thing that happens to audioslave... his car actually dynos really well

I'm guessing because usually dynos start above 2500rpm.

Also I believe not everyone will notice it, I only started noticing it at autocross when I was trying to launch the car without getting much wheel spin, so basically let the wheels start rolling, then go WOT. That is when the hesitation is most apparent for me.

[Yoko22R]

I saw you ordered the low pressure fuel sensor. Did you ever get that changed?

[strokemycocktus]

Originally Posted by Yoko22R

I saw you ordered the low pressure fuel sensor. Did you ever get that changed?

It arrived today and I was hoping to do that right away. Then I noticed I have the old type in my car, and as you can read in TIS it's not a straight forward swap - so now I'm waiting for the rest of the parts to arrive :

I am getting constant faults for this sensor now, so hopefully it will solve something as well.

[SYT_Shadow]

Originally Posted by tdott

I'm guessing because usually dynos start above 2500rpm.

Also I believe not everyone will notice it, I only started noticing it at autocross when I was trying to launch the car without getting much wheel spin, so basically let the wheels start rolling, then go WOT. That is when the hesitation is most apparent for me.

Agreed that an issue at 2500 wouldn't come up in a dyno, what is surprising though is that on one hand the car seems broken at 2500rpm but on the other it feels fantastic in mid/high rpm

I found audioslave's issue to be pretty clear

[strokemycocktus]

Originally Posted by SYT_Shadow

Agreed that an issue at 2500 wouldn't come up in a dyno, what is surprising though is that on one hand the car seems broken at 2500rpm but on the other it feels fantastic in mid/high rpm

I found audioslave's issue to be pretty clear

Here's a dyno I had right after I bought the car, it was when the x-pipe was catless. It's pretty obvious I think.

[SYT_Shadow]

Originally Posted by strokemycocktus

Here's a dyno I had right after I bought the car, it was when the x-pipe was catless. It's pretty obvious I think.

I can't see anything

[strokemycocktus]

Maybe now it will work, sorry.

[strokemycocktus]

And here's my most recent one (with x-pipe and afe intake, no tune).

[tdott]

So I did some logging with BMW logger and this is what I got, it looks like it actually starts at 2k rpm for me. You can see the first arrow pointing to the rpm value, it doesn't increase smoothly, at 2k rpm it flattens for a split second then increases evenly after this, while throttle is 100% the whole time and DSC is off.

The second arrow shows a dip in AFR ratio at this point. It dips to 0.84 then goes to 1, then works its way down a bit.

Not really sure what this means or what it points to:

[strokemycocktus]

Originally Posted by tdott

So I did some logging with BMW logger and this is what I got, it looks like it actually starts at 2k rpm for me. You can see the first arrow pointing to the rpm value, it doesn't increase smoothly, at 2k rpm it flattens for a split second then increases evenly after this, while throttle is 100% the whole time and DSC is off.

The second arrow shows a dip in AFR ratio at this point. It dips to 0.84 then goes to 1, then works its way down a bit.

Not really sure what this means or what it points to:
[img]https://i.postimg.cc/gkF8KKL5/M3-log.png[/img]

Looks like it's the same thing, only earlier. Can you post a graph with ignition timing, fuel pulse and lambda integrator as well? I am curious if these are affected the same way.

What gear was that pull at?

[tdott]

Originally Posted by strokemycocktus

Looks like it's the same thing, only earlier. Can you post a graph with ignition timing, fuel pulse and lambda integrator as well? I am curious if these are affected the same way.

What gear was that pull at?

This only happens in first gear for me.
Atleast I haven't really been trying it at that low rpm in other gears.

This is the graph with timing, fuel pulse, lambda 1+2

[strokemycocktus]

Thanks man. Same stuff as mine.
I notice it in all gears and it does kind of brother me in city driving when I'm too lazy to downshift lol.
Anyway, I'll be posting all updates here and if I manage to find the solution I'll be sure to let you know, of course I'd appreciate if you did the same

Plan for now:
1. Fuel pressure sensor
2. Pre cat O2 sensors
3. Spark plugs
4. Attempt to get a custom tune from Alex

SYT_Shadow did you use a special hfc tune, a catless one, or just some basic stage 2 tune?

[SYT_Shadow]

Originally Posted by strokemycocktus

SYT_Shadow did you use a special hfc tune, a catless one, or just some basic stage 2 tune?

The E92 is running a HFC tune, it was a basic off the shelf tune, no special goodies, no data logging, no dyno'ing.

My dyno graphs start at like 3k rpm, it feels unnatural to go WOT in 5th gear at 1500rpm

[tdott]

Originally Posted by strokemycocktus

I'll be sure to let you know, of course I'd appreciate if you did the same

Plan for now:
1. Fuel pressure sensor
2. Pre cat O2 sensors
3. Spark plugs
4. Attempt to get a custom tune from Alex

Will do, my plan is to try new injectors or flow tested/cleaned ones. They seem cheap enough to just buy new.

Then maybe o2 sensors since mine are original. My plugs are fairly new.

Should I send Alex my logs? Not sure if he'd wanna do anything. He suggested I had some type of hardware issue last I brought up an E85 issue and had no codes. This problem was also there on e85 but had other problems too. Since switching back to 93 tune all the other problems went away except this one.

[SYT_Shadow]

I called my other friend today, the one with the ESS stage 2 tune and Bimmerworld xpipe. He confirmed zero issues.

We'll have to get an ESS tune for Audioslave686 's car and see if that makes a difference, although I doubt it's that

[bennylagoon]

Hello everyone and sorry if my english is bad

Same problem for me, between 2krpm and 3krpm, when i floor it there is a lack of power, sounds like misfires and then after 3krpm the car just pull normally. Catless x-pipe and E85 Alex Alpine Stage 2 tune. No codes recorded.

Few weeks ago I had to pass emissions here in France so I need to reinstall the OEM x-pipe with an Alex Alpine E85 stage 1 tune. Changed the seals between the headers and the x-pipe and everything was ok, no misfires or lack of power. Passed emissions briantly so after that i wanted to reinstall my catless x-pipe.

So i thought it was the seals. Just put new seals with my catless x-pipe and let the E85 stage 1 tune to see if there are misfire under 3krpm. And there are misfires or everything else. When I floor it, I have a lack of power (and sort of burbles) between 2krpm and 3krpm, and after 3krpm everything is ok and the car pulls hard !

Then put the stage 2 E85 tune.. Same problem.

Test with an other fuel pressure sensor (From an other M3). Same problem.

I will double-check for any exhaust leak.. and maybe test with SP98 fuel.

[Audioslave686]

Originally Posted by bennylagoon

Hello everyone and sorry if my english is bad

Same problem for me, between 2krpm and 3krpm, when i floor it there is a lack of power, sounds like misfires and then after 3krpm the car just pull normally. Catless x-pipe and E85 Alex Alpine Stage 2 tune. No codes recorded.

Few weeks ago I had to pass emissions here in France so I need to reinstall the OEM x-pipe with an Alex Alpine E85 stage 1 tune. Changed the seals between the headers and the x-pipe and everything was ok, no misfires or lack of power. Passed emissions briantly so after that i wanted to reinstall my catless x-pipe.

So i thought it was the seals. Just put new seals with my catless x-pipe and let the E85 stage 1 tune to see if there are misfire under 3krpm. And there are misfires or everything else. When I floor it, I have a lack of power (and sort of burbles) between 2krpm and 3krpm, and after 3krpm everything is ok and the car pulls hard !

Then put the stage 2 E85 tune.. Same problem.

Test with an other fuel pressure sensor (From an other M3). Same problem.

I will double-check for any exhaust leak.. and maybe test with SP98 fuel.

Did you experience this issue before going to stock x-pipe?

[bennylagoon]

Originally Posted by Audioslave686

Did you experience this issue before going to stock x-pipe?

Yes definetely. My experience is (Ordered from the oldest to the newest, begin 1 year ago) :
- Stock x-pipe and stock tune (SP98) : No problem or doesn't feel it
- Catless x-pipe and stage 2 tune (SP98) : Small misfires
- Catless x-pipe and stage 2 tune (E85) : Big Misfires
- Stock x-pipe and stage 1 tune (E85) : No problem or doesn't feel it
- Catless x-pipe and stage 1 tune (E85) : Big misfires
- Catless x-pipe and stage 2 tune (E85) : Big misfires

When you look at it, you want to blame the catless x-pipe but i want to datalog with the 2 x-pipes to see if the problem is the same but "covered" with the stock x-pipe.

To complete that, i'm experiencing very, very long cranks for the first start of the day with E85 since 6 months.

I think the whole problem is fuel supply related, but don't know where to begin. Pump ? Pump Controller ? Injectors ?

I expect the logs could give me an answer. Will try to log tomorrow.

[strokemycocktus]

I have replaced the fuel pressure sensor yesterday, a far as I can tell nothing changed. I will record some logs later today to compare.

I also still have long and rough cold starts with my 100 octane and cold start delete stage 2 tune. I will request a 98 octane tune to see if it changes. I will also record my cold start so you can hear what I mean.

bennylagoon what xpipe do you have? Did you replace your O2 sensors?

My issue seems to be the same as well, zero problems with the stock xpipe and problems with the aftermarket xpipe, regardless catless or hfc.
An exhaust leak would be most obvious, but how could it be possible to have issues just at 2-3k rpm AND literally nowhere else. Also the shop that installed it for me has checked twice for leaks and found nothing.

Looking at my logs it looks like the O2 sensors are getting a rich mixture read (low O2 in exhaust fumes), which makes the ECU to cut fuel by reducing pulse width. Since cutting fuel does not improve performance, but makes it worse, I think the way ECU reacts here is inadequate. If so, there are 2 options - either sensors are faulty and read wrong, or there actually is low O2 level detectable in the exhaust fumes at 2-3k rpm with some x-pipes for some reason, which to me seems rather unlikely.
Honestly if I change my O2 sensors and see no improvement I'll be probably out of ideas :

[bennylagoon]

Originally Posted by strokemycocktus

bennylagoon what xpipe do you have? Did you replace your O2 sensors?

It's a custom catless x-pipe, made here in France by a professionnal welder. Honnestly not a very good job. I should replace it. But I don't think the x-pipe is the source of the problem.

I have not replaced my o2 sensors.

I think the problem is always here, stock x-pipe or not. It's Just more obvious with catless or hfc x-pipes.

It's fuel related so it could be a lot of things :
- o2 sensors are essential for a good reading
- fuel pump controller
- fuel pump
- fuel pressure sensors
- injectors

[strokemycocktus]

Originally Posted by bennylagoon

It's a custom catless x-pipe, made here in France by a professionnal welder. Honnestly not a very good job. I should replace it. But I don't think the x-pipe is the source of the problem.

I have not replaced my o2 sensors.

I think the problem is always here, stock x-pipe or not. It's Just more obvious with catless or hfc x-pipes.

It's fuel related so it could be a lot of things :
- o2 sensors are essential for a good reading
- fuel pump controller
- fuel pump
- fuel pressure sensors
- injectors

Could you share a photo of the x-pipe? I am curious.