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monkeygod11

135i n54 on track stutter when hot

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Haha I'd say there are plenty of other options out there with other manufacturers... even most of my old Hondas would've run circles round my old stage 1 tuned 135i on the track

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I just meant cost of the car to begin with, everything Japanese here that could be decent on the track is well over priced compared to the US and UK. :(

On my first track day I was getting overtaken by a lot of old Hondas but think that was more the driver than the car haha

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So Saturday had less stutter/hesitation but also had 3 out of 5 sessions stuck in traffic. 

The 2 sessions I got a chance to go for it (ignore the lap times times, biggest upgrade needed is the driver) I got a bit of the hesitation and then on my last lap going over the finish line I got limp mode and 30FE DME: Turbocharger. boost pressure too high and 31 00 DME: Boost-pressure control, deactivation codes come up. Cycled the ignition and is running ok again. Have attached logs but don't know if what I was able to capture is helpful.

Engine oil temp never went above 125c on the dash gauge. So thinking my hesitation could be tune/boost related as opposed to engine or trans temps (granted have no idea what temp the trans actually is), if anyone has any thoughts they're much appreciated. 

Log-20210515-124457 Pukekohe Park 15.5.21 - session 3 - Interpolated.csv Log-20210515-152154 Pukekohe Park 15.5.21 - session 5 - Interpolated.csv

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Faulty boost solenoids? Pretty common issue on these. Not sure if they can actually be tested. Mine went bad on my n55 135i, replacing it fixed a number of issues I was having and was relatively cheap.

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My boost solenoids were replaced about 18 months ago but I'll keep them in mind as they may have crapped out since then, thanks 

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Was having a look at your logs but not having much success. My usual log viewer won't load them for some reason, so I had to use the off course substitute from the internet :) It can't handle the whole log, so I just picked a few lines as a sample and trimmed out all columns that didn't have much relevance. Having done that (and since I am unfamiliar with fly be wire trickery) I'm not sure what I am looking at ? The TPS appears to flatline at 87.451% and the MAP at 120kPa.

I believe that the ECU will set the max TPS where it thinks it should be, but I doubt that 120kPa is correct as that is only 3psi of boost !!! Overrun and idle kPa looks about right at 30kPa or thereabouts, so I don't understand what is going on with the MAP reading ? Temperatures look good and timing goes up and down as expected. Is it possible to select other channels from the OBD port for logging ? For example fuel pressure and AFR ? These would be a more helpful for trouble shooting.

Cheers...

Generic Data Log.png

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Thanks John, will see what other sensors I can log and if I can get fuel pressure and AFR I'll try do some pulls somewhere and see if I can get anything useful, but looks like I'll have to get my hands on a MHD to get some decent logs at this rate, have attached in vbo format in case that works with your normal log software. 

Thanks for taking time to help out.

Log-20210515-124457 Pukekohe Park 15.5.21 - session 3.vbo Log-20210515-152154 Pukekohe Park 15.5.21 - session 5.vbo

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Just about all log viewers work fine with comma delineated .csv files. But the viewer I like is one that was provided by an ECU manufacturer and it is a bit fussy about the headers and the order in which they occur. There is one oddity that I noticed in your logs, and that is that sometimes the figures in the columns randomly change from values with 3 decimal points to values in whole numbers ? It is almost as if the logger has lost the input signal and just reverted to filling in the gap with the last known value (rounded up or down) until it gets the signal back again.

Are you able to discover if this is something that VBOX would do ?

The only time I have experienced anything like that is when my old laptop could not keep up with the sample rate of the ECU output. I see that the VBOX has pretty high sample rate so I wonder if it is a bit fast for your tablet ? Of course, if the VBOX logs internally for you to download later, this situation would not apply.

Cheers...

table sample.png

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3 hours ago, monkeygod11 said:

Another thing to look into! haha will see what I can find out.

Had a little look at the logs and she is running hot and looks to be pulling timing. I see 70c + for IATs (assuming data zap has got everything correct).
No boost reduction, looks to be holding 17psi. I do see the throttle does look to close around 4000 rpm which I'mt not sure if is DME or you are just letting off. 
Also are you left foot braking? 

Here is the link for Datazapme with your logs. (If you don't want them here I can remove) just easy to see/use data. 

https://datazap.me/u/ninjaspartan/forum-135i?log=0&data=9-18-20-22-23-24-26&zoom=8598-9091

MHD is pretty good for data logging IMO and checking engine fault codes as well. 

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Thanks for that I'm still on the stock intercooler so an upgraded one should be next on the list right?  Will the high IAT be causing the timing to be pulled which could be causing the hesitation/stumble? Could be that it needs retuning?

Wasn't letting off on the straights unless I hit traffic and the hesitation happens around 4000 so could be the DME. Nah no left foot braking I'm still a newbie on track so keeping it basic for now. 

Happy for the logs on there, looks like a good tool. 

Yea looks increasingly likely I need to get my hands on an MHD,

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As it happens, when I downloaded the logs from Datazap it seems that somewhere along the way the headers got modified so that I could view them with my usual log viewer. Hoping to learn something I thought I would take a look and see if I could figure out what goes on with the MAP reading. My car logs MAP in psi relative to atmospheric pressure, thus boost logs from zero to 17psi (for example) and off boost logs from zero down counting backwards... idle is around minus 7psi. I am not familiar with how other logging setups log MAP but I don't know of any way that you can have idle at 30kPA and 17psi of boost at 120kPa on the same scale !!!

Be that as it may, I have attached a couple of screenshots showing what I believe to be the dying stages of your last Session 5 race lap. Both of them show what appears to be an anomaly in the ignition timing (marked with the traditions red circle for the hard of vision) while the car is coasting down. Those two spikes are more than 10 degrees of advance, and providing the engine is not in fuel cut, that would cause a couple of "bumps". Curiously, the Excel figures do not show anything unusual happening at that time point so I have no idea how they get to appear in the graphs :huh:  I can't view the VBOX logs... maybe you could check that one.

I don't know anything about how the DBW system works, but I guess the two throttle position readings are what your foot is commanding vs what the DME decides the throttle butterfly should be doing. As mentioned above , there is a big jump around the 602 second mark, but that could just mean that the DME decided that you were already on the boost limit and there was no point in opening the throttle any wider ? Maybe someone who is more into BM engine controls can help you out ?

Cheers...

puke session5 shot 02.png

puke session5 shot 01.png

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Thanks John, really appreciate that, will be useful for me to ask about when I go in and speak with the mechanics.

Thinking I'm going to get the bigger FMIC from the store you used on aliexpress, HZ racing and MHD and go from there before I start spunking big money on oil and trans coolers.

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12 hours ago, monkeygod11 said:

Thanks for that I'm still on the stock intercooler so an upgraded one should be next on the list right?  Will the high IAT be causing the timing to be pulled which could be causing the hesitation/stumble? Could be that it needs retuning?

Wasn't letting off on the straights unless I hit traffic and the hesitation happens around 4000 so could be the DME. Nah no left foot braking I'm still a newbie on track so keeping it basic for now. 

Happy for the logs on there, looks like a good tool. 

Yea looks increasingly likely I need to get my hands on an MHD,

Hot intake temps will absolutely pull timing. This is based on the Tune.

Here are the stock timing reductions based on Temp for the 335is (IJEOS) DME verson. I would imagine its the same as the 335i. 
So above 50c its pulling 5.5 to 8 degrees. 

image.png.6fc6e61576556384df4e348035c8c36b.png



Also as John mentioned the two throttle readings are a bit odd. Generally you have throttle postion IE the postion of pedal, and the postion of the actual throttle body. So you have a requested throtle and actual throttle in a sense. 

As for getting a larger intercooler, yup that is definately something to look at. Especially since you take it to the track. 

 

 

 

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25 minutes ago, Ninjaspartan said:

Hot intake temps will absolutely pull timing. This is based on the Tune.

Right so unless I've not grasped this properly it's really sounding to me like it's the timing being pulled due to high IAT as where I'm feeling the stumble the most is 3k to 4k which has the biggest timing pull there.

Will get the intercooler upgraded and see how things go, if no improvement I'll get MHD and use the tunes from that instead of the current one.

Also would it be worth getting the step colder spark plugs as well at the current power (340whp)?

Thanks so much for all the advice from you guys!

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Again, just guessing, but the DME charge temp vs timing correction table is probably calibrated to keep the stock engine clear of detonation. So the engine loses power gradually as the charge temp rises, rather than having the ECU suddenly pull 8 or 10 deg of timing when the knock detector reacts to the onset of det. It's a pretty good system for the stock tune, but a bit harder to predict how it will cope with a custom tune if the correction table is not adjusted for the higher cylinder pressures.

Yes... you would definitely want to go one step colder on plugs for race day. They will be OK for normal driving providing your daily commute does not involve extended crawling in city traffic.

Cheers...

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I'll see if I can talk to the guy who tuned it and see what he did in terms of the correction table.

I semi regularly have about a 30min crawl (like couple of times a week) the colder plugs will be ok for that right?

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Shouldn't be any sort of a problem. On another car (not a BM) I got misfiring on a long hard pull (flying quarter mile) with stock plugs. Cured it by changing to one step colder and never bothered to change back. Car was a DD for my wife for years and never had any issue. If you up the boost from standard and get misfiring under prolonged high load, it is pretty much standard practice to go one step colder and close the gap a little.

Cheers...

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I was looking to see where in the engine speed range the N54 achieved peak torque and found this graph. I was expecting to see the normal "twin peak" type torque and hp curves, so a bit surprised to see the flat peak torque curve starting from 1500rpm. Looks like those two little turbos spool so early that BM have to limit the boost to stop breaking things. Having two turbos the same size probably makes it more difficult to run them sequentially as some makers have done, and torque limiting gets around the problem of the turbos appearing to run out of puff very early.

Controlling the N54 and keeping the engine safe under all driving conditions obviously will require a lot of clever tuning to get all the variables working in harmony to achieve maximum performance. I don't understand half of what the DME is doing... so I don't intend going any further than MHD and a few hardware upgrades on my car. It goes well enough to keep me happy, and hopefully I can get a decent run out of it without anything expensive breaking :)

Cheers...

N54 torque curve.png

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5 hours ago, jon dee said:

Shouldn't be any sort of a problem. On another car (not a BM) I got misfiring on a long hard pull (flying quarter mile) with stock plugs. Cured it by changing to one step colder and never bothered to change back. Car was a DD for my wife for years and never had any issue. If you up the boost from standard and get misfiring under prolonged high load, it is pretty much standard practice to go one step colder and close the gap a little.

Cheers...

Thanks will get some new plugs from FCP euro.
Yea I'm ordering a MHD plug so I can log everything and have the option for their tunes if the new intercooler and plugs doesn't sort my issue.

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On 5/10/2021 at 1:45 PM, monkeygod11 said:

Still on the stock intercooler. 

Yea that's true at the time I wasn't thinking of track days but now I'm doing them I should probably go back and see if the tune should be changed. Will ask them about the tune file.

Have got hold of a Bluetooth obd dongle thing and will use it this Saturday to show live data and try and get some logs to hopefully point me in the right direction of where to upgrade first. 

What sort of temps should I start worrying about? 

Thanks for your advice so far!

Firstly....you can always (to my knowledge) use the MHD Flasher to backup whatever flash file you have in your DME....you don't want a trip to the dealer (if you'd take it there) or somewhere else to 'helpfully' wipe your custom tune. You do not need to have an MHD licence or be running an MHD flash to use the backup feature in the app. It's pretty much instant too (you just need the D-CAN cable plus an OTG adapter for the phone). 

Secondly I'm a bit saddened to hear of a custom tune and tracking on the STOCK inter-cooler. It's pants for aggressive street use...it's going to be terrible for track. However without the data it's not possible to know for sure where the stuttering is coming from. 

I strongly recommend a JB4 too, you'll get much safer boost control and the logging is excellent. (It's worth it for the logging alone IMHO). You also get an awesome flash of the blinkers in the cluster when oil is upto temp for full boost. 

Logs , logs and more logs are the key here and it will become apparent where your issue is in that case. 

I completed an N54 rebuild about six months ago and am still getting to grips with the platform over the last 10 months or so but have a reasonable amount of hands on experience at this point.   

 

Unrelated and possibly unhelpful rant below -

Finally, what's this "Buy an M3" advice for occasional track use? That's like saying these days to buy a collectible Gibson guitar and trash the hotel room with it. Any of the N54 or N55s will destroy the non-turbo M cars and cost you a fraction of the money ..even in the long term. The E46 M cars need their chassis all bonding back together and what not at this age too...the list goes on...

- Rant off 

 

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On 5/19/2021 at 11:10 PM, Ninjaspartan said:

Hot intake temps will absolutely pull timing. This is based on the Tune.

Here are the stock timing reductions based on Temp for the 335is (IJEOS) DME verson. I would imagine its the same as the 335i. 
So above 50c its pulling 5.5 to 8 degrees. 

image.png.6fc6e61576556384df4e348035c8c36b.png



Also as John mentioned the two throttle readings are a bit odd. Generally you have throttle postion IE the postion of pedal, and the postion of the actual throttle body. So you have a requested throtle and actual throttle in a sense. 

As for getting a larger intercooler, yup that is definately something to look at. Especially since you take it to the track. 

 

 

 

That table is mapped to load not temperature so you can't read the timing correction off directly against temperature...some logic in the programming will enter into that table based on the load an RPM and then apply the timing correction it finds there...but the point is accurate...you'll get timing pulls at high IATs...

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1 hour ago, HalfJobHarry said:

That table is mapped to load not temperature so you can't read the timing correction off directly against temperature...some logic in the programming will enter into that table based on the load an RPM and then apply the timing correction it finds there...but the point is accurate...you'll get timing pulls at high IATs...

Good to know thanks! I thought it was temp as I remember seeing something about timing was reduced after 50c. 

Do you know if it is linear based, so higher temps more timing reduction or once X temp is reached it reduces timing based on the load/rpm? 


 

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7 hours ago, HalfJobHarry said:

Firstly....you can always (to my knowledge) use the MHD Flasher to backup whatever flash file you have in your DME

Thanks yep have backed up the current tune just in case.

7 hours ago, HalfJobHarry said:

Secondly I'm a bit saddened to hear of a custom tune and tracking on the STOCK inter-cooler.

A 5" intercooler will be in soon :)

7 hours ago, HalfJobHarry said:

You also get an awesome flash of the blinkers in the cluster when oil is upto temp for full boost.

I want JB4 just for this haha

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13 hours ago, monkeygod11 said:

:)

I want JB4 just for this haha

Good to hear you have the tune backed up and have a new IC coming. My initial testing with the 5" from HZ Racing store (ali express) has been very positive, I was worried about a larger pressure drop than stock ...so far logs are showing the opposite...that it's less restrictive. Also no appreciable increase in lag. 

IMHO the JB4 is an essential component in any tuning effort, sure you can tune the flash itself...and probably should...but why would you not want selectable levels of boost along with great logging and safety features. The ECU alone just isn't setup to protect from some of the situations we can get our engines into with the changes we are making. 

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