Technical Intake manifold exploded-BACKFIRE- Reflex+,PI,E85

Neg89

Specialist
Jul 4, 2021
67
6
0
So.


I will tell you interesting horror story what happened to my n54 in autumn 2023.

It all started like this


I have 98 ron /flexfuel tune from reputable and well known tuner. Albeit he said that the flexfuel tune is finished at v3 i asked to check if everything is ok and somehow he send me v4. I tested it and i had misfires on the spot. Before that i run v3 flexfuel map filled with e70(actual percentage) and everything was fine. After informing the tuner about it and that i better stay with v3 and can he verify that everything is within safe limits running v3 he refused to do that. Refusal reason=wasting time, because v4 is sent and i should log that. Since i dont wanted to abuse the car with v4 logging because of heavy misfire i and that i was pretty happy with the result of v3 i just stayed with v3. I dont proceeded with v4 logging and map sending to tuner. I drove the same v3 flexfuel map with RON98 maybe 8.000km and still everything was fine. I use car only in summer ocasionaly and was not filling e85 some time because only one filling station awailible + no real need to do so in my area. I need it only when ripping in the mountains which i do only twice a year. And then i went to my annual trip some 4,000 km from my home. Everything was fine, ripped thru mauntain roads, enjoyed the scenery and car. Was riding n54 as i should, no pampering. And then the plot twist happens...


First side turn

Ended in country where e85 is twice as cheap as gas. Since i have been waiting for this moment long time, money and powervise i imediatly filled up with e85 in the first station. With happy heart i traveled aut of urban areas while i was in remote mountain roads. Started to build up pace and WOTted the car. Had misfires on few occasions in cylinder 6. Strange. Ok cleared,repeated, yes the misfire in c6 come on sometimes, but sometimes not. Not that happy, i continued my ride, it was late evening just before sunset and in remote area of not the home country and some 100km left. Since i had misfires before, i was not giving the full power. But in one corner the engine just stalled.



I was not so fortunate because i had my phone changed just few days ago and not even test connected to car. Connected, pulled codes related to HPFP. Nice. Then i noticed thet i dont hear LPFP priming, since i have upgraded LPFP i thought maybe it gived the gost on the spot, or EKPM3 is dead. I have active cooling mounted on EKPM3, but on rare occasions i had shadow code of too much current draw (very rare but happen since i have walbro530) . Since i got spare EKPM i swapped it, but still silence. I have e89 chassis so no acess to the pump without serios work. But after some troubleshooting time in the dark(literally) i found out that the fuse of LPFP was blown and current is even not coming to ekpm3. So simple. The fuse was showing signs of severe heating, little melted. Swapped the fuse and lpfp+engine started on the spot. I think because of much more volume of e85 to be pumped , the pump drawed too much A.



The worst is yet to come

Since it was very late and dark, i did not wanted any more attractions on the road and continued to my guest house. After some 30 mins of driving. When In was in the middle of one tunnel i floored more but maybe not even 100% wot,but probably close. At the end of it i hear pretty severe KABOOM. I do not even know if it happen in the moment i let off the throttle or uppshift, most probably booth. But it was clear that we will not continue driving to destination. Imediatly pulled at sidewalk around the corner, popped the hood and with torchlight looked and found my intake manifold have damage. The longer i looked the worse it become. Which seemed like a runner damage turned out to complete destruction of manifold when i literally pulled it out with my hand. Few wires of PI was also ripped but worse discovery was yet to come. The HPFP pressure expansion tank was out of its place, since it is just glued inside it vas clear that this is the end of trip. It was late night in remote area and i was lucky enought to catch a last passing driver which towed me to safe parking place. In the morning i taked a look at he engine bay , in the intake ports and everything. And went far far away for my other car with trailer to bring this one home.




Intake manifold was in many pieces. The flange mounted to the head was still mounted, but thats it. I was able to observe all the PI injestors and valves. Car was towed home in the trailer. The good news was that no pieces of manifold got inside cylinders. Not so lucky was the HPFP, which is now separated form presure expansion tank. The HPFP is only about 20.000 km old. Shame. I am looking to ways to reattach and refill the oil in pump so it can be used again.




Since i got spare HPFP i swapped the pump, fixed ripped wires for PI, Put on the new manifold, gaskets etc. The car runs fine, but since i am now scared of what happened i tested it only with pump fuel. But tested for long enough to be shure there is no further damage. Throttle body,chargepipe,IC everything is ok. But i definitely know that silicone IC to chargepipe hose have been inflated in that moment. I had few bigger zip ties around in the middle section, to prevent it from rubbing ,they was torn at the connection.




One thing i noticed, that my PCV HIGH side hoses was little loose and had oil wapour at connection to flapper valves, yes i have 2 of flapper valves in paralell. Why? There was too much vacuum , on the idle i was sometimes hearing squeking from the rear crankshaft seal i guess. So i measured VAC and come to conclusion that it pulls too much and need to be lowered. I also have dual catch cans for Hi and Low side.I have plugged ports in head and have external valve fitted to TB. RB valve it is.




The main question of this is, why this happened. Why i got bacfire in the intake manifold and what exactly ignited so good that explosion not only lead to complete destruction of manifold but even ripped the glued tank of the HPFP. (Its good that the wheels ar not glued on bmw, special thanks for this to BMW AG). The intake was walnut blasted some 10.000 km ago, maybe less, but while it have PI they were not spotless clean. Some gunk was there anyway, PI injectors spray at 90 degree angle=not so good cleaning. Was it some carbon piece that was still glowing inside combustion chamner on intake stroke when pi injectors spray. Spark plug too hot? I run 2 step colder plugs and was not ripping hard at all when this happened. On pump fuel i previously have driven many times uphill (think of cilvil pikespeek )that i can even see the turbofold glow in the dark and 0 isuues. Is it connected to e85 at all? There is no explanation on how could possible the fuel form PI accumulate in manifold and to make the mixture because engine was running and manifold is all time vented. Too lean, too rich, something to do with potential misfire in c6.




No, i dont have real time dattalog from that moment. I have dattalog only after i fixed the car and some previous ones. Not that do i know exactly from which cylinder backfire originated. But there must be some place where some kind of spark came. I dont beliewe that manifold explosion was only because of pure boost. Too loud bang it was. Even if it had 30 psi (which it dont) i dont believe it popped that hard. And that do not explain the ripped zip ties on inflated chargepipe-ic connection they was holding before no problem. So this was actual backfire in the intake manifold.



Looking at dattalogs i see that from beginning i had big difference between STFT1 and STFT2, can be 10%. difference. On Pump and on e85. Also i see that Cilinder5 have corrections. Here and there. Maybe i need to start diagnosing PI injectors as well. Because of STFT difference.




I know that here is many expierenced users who can chime in and try to find what happened, I really want to find the root of this


MHD full license,custom tune.
XHP St3 DCT gearbox flash
New O2 sensors.
Pure Stg2 cast turbos (EUROPEAN PURE)
Walbro 535 intank LPFP
Wagner EVO3 COMPETITION FMIC
Catless DP
Silicone OEM location inlets 2"
Retrofitted LPFP sensor
BMP PI with 750cc injectors(Bosch)
Reflex+ PI controller
Drop in air filter OEM location
Upgraded Diverter valves (Audi RS6)
Custom Charge pipe
3.5bar TMAP in chargepipe
Oil catch cans Low and High side
FULL lenght exhaust, with xpipe and resonators in place of secondary CATS.
Plugged PCV ports in head.
Dual oil coolers
Mosselman Oil thermostat
Hydro steering from e90 M3.
 
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  • Wow
Reactions: wheela

wheela

Lieutenant
Jun 4, 2021
1,127
631
0
Twin Cities, MN
Ride
2015 e84 X1 35i Msport
Wow, sorry to hear this. I'm interested to hear peoples' thoughts on this one. Can you post up some logs from your v3 tune? Somebody may be able to glean some clues there. Also, any pics of the carnage?

Edit: You're lucky your car didn't catch on fire...
 
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Neg89

Specialist
Jul 4, 2021
67
6
0
So, Here is two logs. from V3 flexfuel . One some time before "event" and one after i got all back together. In the later e content is dissolved.

I see the trend that cilinder 5 is pulling timing always. But if i remember correctly when i had misfire on v4 it was in cilider 6. And before explosion (after fillup with e85 and starting to push) it was cilinder 6 all the time. Maybe it is DMFW issue and not a real misfire in cilinder 6. And yes i have heard that number 5 is noisy, correct?
Also from the logs STFT difference, is it worth to check injectors PI or Di ones. On which bank? Before i bought Reflex+ i got Reflex lite, and guess what it was defective from day one as new. Only 2 or 3 PI injectors recieved signal at all.

Codes i get in the few hours before manifold popped was
2AAE
29D2
29E0

v3 logs

v4 logs some time ago
 
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carabuser

Lieutenant
Oct 2, 2019
881
1
779
0
UK
Ride
Z4 35i & 335i
Something was injecting fuel when it shouldn't. AFRs take a long time to fully lean out during over run.

Seems to be a lot of people having issues with Reflex. It was so promising to begin with but all I hear now is about their device failures and bad customer support.
 

SLOWESTN54

Captain
Feb 9, 2021
1,246
978
0
23
B.C. Canada
Ride
2007 E92 335i
Something was injecting fuel when it shouldn't. AFRs take a long time to fully lean out during over run.

Seems to be a lot of people having issues with Reflex. It was so promising to begin with but all I hear now is about their device failures and bad customer support.
oh what, Seriously?
 

wheela

Lieutenant
Jun 4, 2021
1,127
631
0
Twin Cities, MN
Ride
2015 e84 X1 35i Msport
Do you have any logs with LTFT for bank 2? That will tell us if the DME is adding or cutting fuel to the target injection mass before applying the STFT percentage to hit target AFR.
 

desmo11

New Member
Jan 10, 2024
8
2
0
Yeah, port injection with ethanol/methanol can lead to some fireworks. This is something that concerns me on the reflex that it doesn't have injection phase control. This can lead to a great deal of fuel in the manifold which can certainly explode when/if a backfire occurs. Examples of this are when the Honda indycars blew their plenums in the early '00s on the back straight at Indy.....they blew the engine covers off and put them into the golf course outside of the course.

One really wants well targeted injectors, lower duty cycle (say 50ish%), and MUST have phase control. Otherwise the fuel charge cannot really be tuned to enter the runner when the tuning pulse is optimally placed at the injector location at the time of injection. Bias of high/low injection and timing/tuning is a very big deal in engine development and can cause some real issues if not done properly.
 
  • Informative
Reactions: houtan and wheela