N54 rail pressure at idle Mar 31, 2025 · Among performance enthusiasts, the BMW N54 engine stands as a cherished powerhouse because of its remarkable potential for modification and outstanding operational capabilities. (Logs of coming to a stop in neutral show a drop in mean rail pressure). I do experience stuttering in a sense when accelerating. I then checked the fuel rail pressure via the Torque Pro app (not ideal but I already had it). Jul 28, 2016 · Velocity26 - i'm trying to just figure out the long crank problem. If your HPFP Actual pressure is dropping below 1500psi anywhere its time to start looking into either adjusting your tune to be less aggressive or upgrading the LPFP system if you haven't done so already or adding supplemental fueling via a secondary rail or similar. Do a log as suggested. Then when just idling it holds around 50psi then will intermittently drop to 12 or 13 then back up to around 50 immediately. The EKPS converts this request signal into a nominal voltage. Although enthusiasts regard this engine as legendary, it has multiple annoying problems. In general there's little reason to change the stock DI fuel pressure targets at idle and cruise, however we will normally want to be as close to the maximum achievable pressure as we can get under high load, high rpm operation. Then upload the . As "HotGuy" suggests, the 2AAF code relates to LPFP output, as measured by Low Pressure Sensor at engine. Part number: 13537622231 Under load at with 50ish% pedal (according to Autel scanner) I’m reading 2,300+ psi at the rail. Stabilize around 2500 rpm in 3rd gear with DTC fully off 3. I saw my hpfp sit at 700 psi on idle and my lpfp was sitting at 32-34 psi on idle. Dec 24, 2023 · Awesome! Thanks for the tip. Dec 6, 2024 · The car idles a bit better now. But when I turn off the car, it dips to 100 psi immediately. The HPFP pressure is maintained with a closed-loop system. Still doing the same thing. By comparing the current pressure in the feed line to the high-pressure pump with the target pressure, the engine management system sends a request signal across the CAN bus to the EKPS. Fuel pressure regulator may also be the culprit. The pressure then increases somewhat with RPM, but not in a consistent manner. Ive seen logs where people just generally have a weak hpfp and it crashed down to 600-700 sometimes, and ive seen logs where peoples hpfp are fine, they dump in a lot more e85 content than the fuel system can handle, and it crashes down to 600-700 lol Dec 11, 2019 · I am trying to diag a no/low rail pressure situation, cant get this car to start When cranking I see like 80-85 psi on the LPFP, but less than 100psi at the rail. I'd be interest to know what your reading is at idle and at 55mph. The car goes into limp mode and right after dies. After replacing MAP sensor, all air management data is now correct with the same issue. As I understand it, that pressure SHOULD be steady at 72 PSI, but the HPFP pressure fluctuates. F40Model Year: 2019 + Previous Generations; F20 / F21Model Year: 2012 - 2018. 2011 335i, FBO, N55+ Turbo, full E85, S55 intercooler, etc. the rail pressure changes with vacuum to maintain 40psi across the injectors. I am going to go ahead and post up my current HFPF/VCV tables, but they are definitely A WORK IN PROGRESS AND USE AT YOUR OWN RISK. 000 hPa); but the fuel mixture data display indicators -30 % for both banks: obviously, the rue rail pressure is significantly higher. Details on the car: Early F10 N55 with rotary n54 style HPFP Only mod is VRSF Catless downpipe and OEM M5 Mufflers Coils/plugs/injectors are relatively new (OEM BMW parts) Stage 2 MHD 91 Octane tune at the moment May 4, 2019 · If dropping below 50psi it indicates a problem with your low fuel pressure pump. 5 psi) then when I start it it goes down to around 3800 hpa and when I start to drive goes to 3400. That assembly also contains the fuel filter. the FPDM (fuel pump driver module) is controlled by the PCM to deliver the correct rail pressure. What should fuel rail pressure be at idle? Dec 19, 2020 · How to Datalog 1. e90post. My high fuel pressure at idle is around+- 48000 hpa (680 psi), and low pressure is 3400 hpa (49 psi). 000 hPa (instead of necessary 150 . Press the Monitor (auto log) button 2. May 27, 2021 · I know for rail pressure, the maps used by the dme are the external maps (BMW), meaning its the maps with all caps abbreviations. May 28, 2021 · To answer your question, LPFP pressure of 4975 hpa (hectopascal) is 72 PSI, and THAT is normal. The car stumbles and throws the codes for Misfire fuel injection deactivation for cylinders 2, 3 & 4 and also misfire detected 2, 3 & 4. I crack open a fuel line and there's nothing coming out. Aug 3, 2020 · As far as the fuel pressure, I wouldn't worry about it too much yet. I am specifically trying to track down the cause of a he Jan 20, 2020 · (6) After the highway driving and long pull, I expected to have the racing rail pressure at idle, but did NOT have it. According to the Bentley manual, the residual pressure is supposed to be held at 5 bar +-0. If I throw in some starting fluid on the air filter it fires right up for about 1-2 seconds. No changes. Pulled codes with Inpa and it had cylinder injection cutoff, pressure in high pressure system too low. Nov 24, 2020 · Well, quick update. I believe most fuel maps ramp up to 15-17 magapascals which is over 2k psi. Apr 19, 2019 · Monitored the Fuel Rail Pressure - Has Dropped to about 668. " Running an etune, a LPFP upgrade is definitley advised. 44FB Rail pressure plausibility, general entry When the HPFP failed in my Model-Specific Engine Tuning & Modification Discussion. This then throws the code to 29e2. It’s an early model that uses the N54 type HPFP and it looks original. Initial road test showed MAP senor readings off the charts (24 PSI at idle). Aug 28, 2011 · Rail Pressure: Expected value, idle: 750 psi Was: 738 psi (converted from 50,902 hPa reported by the reader) Now: 708 psi (converted from 48,790 hPa reported by the reader), so at that point in time in the pic it was a touch low Apr 11, 2022 · Pressure regulation involves voltage control. Check your fuel pressure, that is primary information for troubleshooting. Mash the pedal, shift at 6000 and hold at 2-3s after the shift into 4 4. From what I've observed on my own car, sometimes, presumably when the fuel system is unable to maintain its target, it will go into a sort of "failsafe" mode where it disables the closed loop correction and runs a static 55% duty cycle at lower loads, and 100% at WOT. In this situation – check the rail pressure sensor, it’s connections. I noticed that when it did the hiccup the rail pressure would drop from 800ish psi to like 650 but would then recover. Did u find the issue?? 2009 bmw 535xi, getting code 29f3 with 94. Aug 22, 2024 · <300PSI rail pressure at idle? Bimmerpost ☰ Model Selection. In this video I walk you through the process of diagnosing a fueling issue on your N54 powered BMW. Jun 27, 2022 · Working on an '04 LLY with 222K on the clock, customer complaint is low power at WOT. Keeps rising up to 2300ish psi and injectors start ticking like crazy at Idle. Here is a log. This causes the car to blast the radiator fan to full power and go into limp mode. <300PSI rail pressure at idle? Bimmerpost ☰ Model Selection. but when i put it in gear it misfires so bad, i have no code other than 2FBE, Fuel pressure after engine stop. BMW’s N55 engine began production in 2009 and… Read More BMW N54 vs. Really aggravating. Replaced my LPFP and I have a nice smooth idle so far. Low pressure is fairly steady just below 70psi but does drop to 60psi when I get near peak boost. Jul 6, 2022 · Anyone know what fuel mode 22 and a surging rail pressure at idle means? Rail pressure oscillates between 680ish to over 2100psi at idle and changes from Fuel mode 2 to 22 when the rail pressure spikes and then changes back to 2 when rail pressure comes back down to normal. Is this normal or should the value be at a stable number? MAF sensor seems to follow the pattern as it also jumps from 10-25 g/sec. To solve problems with the wide distribution of parameters of piezo injectors: in short openings (because of which in the case of N43/N53 series, a range of precise measurements are made in Stratified charge mode and these measurements are not available for N54), Rail pressure in idle and in low torque conditions is reduced to 50 Bar (the max BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Fuel Mode 22 and Rail Pressure Spike at Idle In this entry, I will explain the concept of HPFP pressure maintenance. 5. It doesn’t have a separate fuel pressure sensor like the N54, it’s built in to the fuel pressure regulator. Fuel Mode 22 and Rail Pressure Spike at Idle. In the picture: Rail pressure sensor is marked. Looking at the MHD monitor logs, when the RPM rises, the only other thing which changes is the fuel rail pressure - increases to 750-800psi. rail pressure is as if reduced: around 61. 90 But has maintained 750-800+ on most startups/At idle. Car still jerks, showing erratic rail pressure, misfires randomly, fan on max, pulling down my hpfp. I’ll rip them out tonight and check the seating. Changed my fuel sending unit out last night and noticed I ONLY have a 29F2 active code (Fuel rail pres) and the two shadow codes; 2FCA and 2FDA respectively. For 09/2011 N55s it’s only available from the dealer, but very reasonably priced, thankfully. csv file in MHD / datalog to datazap. 1. N54. 200. Delayed 3-5 second cranks whether cold weather or not. Turned out my LPFP was acting up (fluctuating pressure) causing fuel starvation at the HPFP and the pressure would dip causing it to hiccup. Nothing. E81 / E82 / E87 Hello, I recently replaced the fuel rail pressure sensor as the o ring broke and the sensor seemed to have “blown apart” so I just replaced the whole line and sensor which I got from fcp euro. I have a bucketed 535 with a healthy hpfp and Im usually at 1800 psi under high load and rarely might drop to 1500 rail pressure on e60. To measure the pressure, the pressure sensor, located in rail, is used. Apr 10, 2024 · When reading fuel rail pressure live data on idle the values go up and down sporadically between 27000-30000 kPa (270-300 bar). N54 hpfp pressure fluctuation Hi all, I'm new to bmws and own a 2007 335i running on stage2* mhd with fmic and cdp. The log still shows that the required rail pressure to 2800 after the actual pressure crashes. Noticing some clear fuelly looking fluid in the open part of the head. On mhd my rail pressure at idle is like 7-800. Compression test results for a cold engine are cyl 1-6 = 175, 165, 170, 160, 170, 165 (psi). High pressure starts at 7, peaks at 15 before dropping to 5 around peak boost. No cel codes. Rail pressure drops and matches the low-pressure fuel pump (85 psi). me (Autologging saves to SD card > MHD fl May 3, 2022 · The car doesn't seem to have any issues other than the lack of rail pressure at WOT on the log and cutting spark when it drops. He did mention that the fuel pressure was fluctuating and that he hooked up a gauge to the LPFP and said it was inconsistent. Sep 1, 2021 · The N54 began production in 2006 and first appeared in the 2007 BMW 335i; in 2008, the N54 was introduced along with the 135i and 535i. Is that normal? I thought the system was supposed to hold pressure for the next start. Aug 21, 2018 · When - at idle, at speed I just measured a 335 today and the Fuel rail pressure at 55mph was 2586. Idle pressure is around 700 psi. E81 I have reset adaptations too via MHD (throttle, lambda, fuel rail) which has not solved it. Car runs fine. I have replaced the rail pressure Sep 1, 2023 · The fuel rail pressure ranges between 6-700 psi to 2000 psi depending on driving condition. 2 after 20 minutes of engine shut off. ] Rail pressure should be approx 700psi at idle (after cold start, mine is around 2000 psi), hopefully New HP fixes your issue. Adaptions reset. Apr 28, 2015 · We recommend 1500psi as the bare minimum target. No check engine light before replacing but now there is and I’m getting a p code for the fuel rail pressure sensor. I also have some CRAZY timing corrections (see screenshots of log). Bimmerpost ☰ Model Selection. For a while it sputtered while cranking, now it just cranks. I think I've got it narrowed down to the low pressure regulator. In fact after sitting in the garage, the rail pressure was very steady @ 715psi. 282 low pressure fuel value and high rail pressure value fluctuating from 680-750psi at idle Replace your lpfp sensor. E81 / E82 / E87 Dec 22, 2017 · high pressure (pressure gauge connected in place of first injector) - 100 PSI so 7 bar- values readen by ISTA were good so rail sensor is fine - I just can not believe that target pressure should be 50 MPa that time and that is 0,75 MPa and engine is still working, bad work but working and car can move. Wondering what should rail pressure show upon Did u find the issue?? 2009 bmw 535xi, getting code 29f3 with 94. Initially the fuel pressure ranges between about 2000-2500 psi, but after 2 minutes (120 seconds) the pressure abruptly drops to a nominal value of about 750 psi. It worked well at idle, but when I rev it up to 3k-5k rpms, I noticed that the pressure in the rail didn't increase at all, actually it dropped to 300-400 PSI, the first times after the idle stabilized the pressure went up to 700 PSI, but after several tries it eventually collapsed to 80-100 PSI, after that it went to limp mode and finally the Ive always read that anything below 1000 psi is a weak hpfp. Fuel pressure at the fuel rail was below what it should have been at idle. 02psi Edit: I should note tho I think there is something wrong with this N55 engine relating to fuel pressure so don't use that as a benchmark. Customer: When I turn my ignition on I find that my fuel rail pressure drops from around 3000 psi to about 75 psi or equivalent to the pressure that the low pressure fuel pump is running out. Today had strange thing happening with rail pressure. AFR on both banks are consistent (around 14 for both bank 1 and bank 2). Mar 25, 2023 · I'm looking for some help to solve a rough idle issue I've had for a long time. Rail pressure stays around 2000psi or higher but I noticed my low pressure starts at ~70psi at the start of the pull but then drops down to 50-55psi from 5500-redline. . Hi guys, Been chasing a cold start misfire issue for a while so decided to do a 3rd gear WOT log. To regulate the pressure, an electromagnetic (bypass) valve, which is a part of the pump, is used. I am thinking its the HPFP. To save the car from stalling, I guess the ECU would make the rpm idle rise to 800rpm, by then fuel rail pressure stabilizing around 750. Part number: 13537622231 Nov 25, 2019 · Car = 2007 335i n54 sedan; Car died while driving. Sep 30, 2020 · Car has brand new Index 12 injectors, high pressure fuel pump, coil packs, spark plugs, and low pressure fuel sensor. Fuel pressure at idle should read 51 psi with the vacuum line from the intake to the fpr disconnected. [Clearly low fuel pressure, WITHOUT INPA, but CONFIRMED by INPA screens you attach. Only moved the car around then turned it off before test. It has a long crank on all startups and I just noticed this morning it has a slight miss at idle. Nov 28, 2015 · i have a bmw 135i N54 DCI bmw performance exhaust and COBB stage1 and i have noticed sometimes after some WOT runs all the way to redline when i come to a complete stop after 10 seconds the HPFP shoots up to 2,200 PSI and sits there and after 10 seconds the injector(s) start to tick louder like its being put under enormous pressure without the Nov 10, 2022 · Hi everyone. I was having issues with a crappy idle that would stumble occasionally. I’d start with that and see if the issue persists. Obviously if you're needing a pulse width of 8-9 ms then you have a problem and more fuel pressure is often a solution. Slow down, stop the monitor. The first shows the fuel rail pressure measured on a short test drive from a cold start. When car is primed, low fuel pressure is around 5000hpa (72. Soon as it would reach 700, it would go lower to 600-500 the car would begin stumble. MHD monitor shows fuel rail pressure jumping to 1800+ on start up, and gradually going down to 700. Is this an injector BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Pop on cold start and rough idle + vibrations - N54 I use Bimmerlink to monitor temps, psi, etc. Dec 13, 2018 · The car would go lean to the point of dying at any load above idle. One of the most notorious problems is high pressure fuel pump N54 failure. If I accelerate for more than a couple of seconds the engine shakes and violently jerks the car, cutting the turbos out and shutting off the HPFP. tried priming pumps before start, Most times 2nd startup will turn the engine over. Low pressure psi is 80 on start and 78-82 on idle. com Mar 24, 2009 · the psi you see in a datalog is NOT rail pressure it is the delta pressure between the rail and the manifold. At idle low fuel pressure is 86 psi. Began monitoring fuel data and found a loos of fuel rail pressure at WOT only while driving. N55 Comparison: Horsepower, Reliability, and Tune-ability Nov 1, 2024 · While driving when putting the car into neutral (6MT) car will drop all the way down to 400-300 rpm, jump back up to 1000, drop again, then raise back to a normal idle. Nov 24, 2021 · Current issue, the fuel rail pressure is dropping from ~2800 down to ~400 after a few seconds of WOT. My lpfp is def bad? I do get 29DC - Cylinder injection cutout at WOT and 2A2D - fuel low-pressure system, fuel pressure. I had a same shadow code but my pressures were fine, will probably need to change HPFP at some point. MHD with JB4. Nov 19, 2020 · 3. I’ve had the car since Nov 1, 2023 · Live data has Pressure around ~5000kPa when idle and ~14,000kPa under acceleration. I ordered and replaced both the high-pressure rail sensor and the updated low-pressure sensor. It is obvious – it indicates incorrect pressure. Dec 11, 2020 · BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > What are my options to increase fuel rail pressure? May 9, 2020 · N54 having LPFP spikes over 110psi! 2007 335i e92 Fuel-it stage 3 LPFP 550 cc PI AIC2 Motiv- FF sensor Running e85 In the process of tuning my car, noticed the LPFP pressure was all over the place, dropping below 40 and spikes over 100psi, so I decided to replace the following: HPFP ( FCP Check you fuel rail pressure. Now I'm getting 2AAF Fuel pump: Plausibility and the original 29F1 fuel pressure: plausibility. BMW N54 owners who learn about the Oct 14, 2023 · Both before and after the pump replacement, using MHD monitor, I noticed the low fuel pressure holding around 50PSI during idle then dropping into the 30s while driving the car then back up to 50psi. For example, KF_PRAIL_H is the external map for rail pressure target and ip_sup_hom is the internal (Continental) rail pressure target that isn't used. www. Jan 19, 2020 · I have gone from a stock 135i (N54) low pressure fuel pump due to low psi (52-42psi) readings at idle and throughout RPM range (rail pressure would drop and cause limp mode), to a walbro 450 and have retained the bucket and Venturi to keep it close to stock as possible and hopefully food my low psi issue. See Below for suggested LOW PRESSURE FUEL PUMP tests. What do i do? So here’s the thing with the N55. Recommendations for diagnosis? May 6, 2021 · Recently I found out how to check fuel pressure in inpa/ista. I’ve swapped the lpfp with the old oem one.
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