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284 Posts
Discussion Starter · #1 · (Edited)
2004 325xi auto -> 5speed turbo with megasquirt

gonna revive this thread. i've more or less finished my supra (for the time being, until the bmw runs).

i've received a bunch of PMs since i've posted this thread about stuff. unfortunately, I lost all the original build pictures with the bottom mount, and the struggle for topmount.

i'll post some pictures here with progress, and update the first post for those interested.

i have no idea what's written in the thread anymore, so i'll simply repeat it:

I picked up the car sometime in 2007, 2004 325xi automatic.

it was comfy, but kind of gutless.

the automatic trans really didn't help either:

fastforward a few years ago, i decided to turbo it.

first attempt was with a straight forward bottom mount turbo on an ebay cast manifold, but who cares, bottom mount was a pain in the ass. the oil scavenge pump made me super nervous, and it just sucked to work on.
intake plumbing was also a massive pain due to the crazy stock intake maifold with the throttle body being hidden away below runner 3-4. the only neat thing about that manifold was how easy it was to get to the injectors. i ended up managing the engine with megasquirt3 and terribly hacked up stock harness. the automatic transmission was slightly modified to hold a bit more pressure, but i really didn't push it that much, only about 9 psi was all it ever saw.

the automatic transmission was managed with MegaShift, another megasquirt project that handles the auto transmissions, that was a massive pain as well, code was buggy and just a bad driving experience, so the decision to swap to a manual was made. then i let it sit for 3 years in the garage, or so.

here's all the juicy bits that people will likely want to see:

top mount turbo:

some of the downpipe pieces, the exhaust is vband from a pipe that's attached to the turbo (it's an ebay 5 bolt flange), vband was the only way to make this work. it's 2.5" due to space.

the manifold is a TCD unit made for m50 or m52 engine, mounted upside down, The manifold has a T4 flange, and one of the standard wastegate flanges. To get the turbo up to where it is, there are 2 extenders, a T4 to T3, and T3 to T3

it was the most straightforward way i could get it to mount, and it fits quite nicely.

naturally, with top mount, oil feed is easy:

and oil return is also, easy, as it's gravity powered.

the transmission is a 5 speed ZF (i think), bonus transfer case (non X-drive) bolted to the transmission already (on the top)

when i got it, 5th would not engage, it turned out that the 5th notch piston was completely frozen, perhaps cause it was cold, so i pulled them out, and now waiting for that mechanism replacement to ship from pelican.

clutch disk, cover, and flywheel are some sort of M3 items:

there's obviously other manual swap bits, new pedals, master/hydraulic lines, shifter, new bushings for everything. etc, i won't bother with those as you all have seen that stuff.

now, one of my annoyances when working on the old setup was the intake manifold, so i looked around and got one of those thai M50/M52/M54 manifolds, and it actually fits !
here are some pictures of the new intake manifold, fuel rail bracket, and cable throttle holder bracket:

and mounted on the car, for test fitting:

it is a stock deadhead (returnless-ish) fuel rail with some 660cc MSD injectors with the right connectors to use with stock harness. mount points have been changed, and i made that nifty fuel rail bracket to hold it all down. but a different fuel rail fits (with entry and exit). using the stock fuel pressure regulator/filter that comes with e46 and mounts under the car (boost-referenced)

now, for the management.

originally, when the car ran on megasquirt3, i had rushed the installation, and tapped all the wires under the hood at the harness, soldered to them, cut them, made it look gross, and basically had a really shitty mess of wires that was a pain to diagnose. ms3 worked perfectly fine, however, even ran both VANOS solenoids with tuning for that. I had J&S ultrasafeguard that managed knock, stock coils were ignited using some sort of toyota camry igniter, that megasquirt ran. as far as tuning the engine to run well, megasquirt was amazing, the wiring I created was not.

this time around, i'm doing it slightly different, i'm taking a stock ecu, tracing where stuff goes inside of it on the connector, and putting connectors on the outside that megasquirt will plug into

here is the ignition transistors taken over and wires soldered to the current-limiting transistors.

there is a small surface mount resistor near each transistor that the stock CPU controls these transistors via that has been desoldered.

the same thing has been done to the injector drivers here:

there are two automotive driver ICs with 20 legs each, that control 3 injectors each. legs have been lifted, and i soldered to the bottom of the connector.

same will be done to the vanos solenoid drivers, fan driver, fuel pump driver, idle controller, knock sensors, and whatever else comes up.

the whole point of this is to use a stock engine wiring harness without having to modify it.

i likely missed a thing here or there, if you have questions, let me know, and i'll go take pictures of what i've done, or explain what the plan is.

more here: http://forum.e46fanatics.com/showthread.php?t=773653&page=14#278 <--- go here

284 Posts
Discussion Starter · #2 ·
i left off last time at the motor mount being entirely in the way of freaking everything, and the TRM trick motor mount not fitting. tough **** eh ?

so first thing, make a jig for the stock mount:

it eventually ended up with some holes in it for where the stock mounting holes are, just to be proper.

trm mount in the jig hooked by the rubber mount part:

yeah, that ain't gonna work.

so cut, grind a bunch, and reweld:

they at least look somewhat similar now

moving on, the wastegate housing with the neck and vband at the end, look at those crappy welds

284 Posts
Discussion Starter · #3 ·

add some o2 bungs to it

try it out

should do for now, i know i will be replacing that piece, most likely with a proper wastegate hanging off a tube thing, i've got a real tial lurking around the garage somewhere, just need to track down one of those tubes, and reweld the downpipe. whenever it happens, it happens.

the motor mount hooked up and supporting the engine:

SLIGHTLY better.

although now that i look at it, i think it will hit the rubber mount housing thing if the engine moves around too much, i'll have to check it out and see what the clearance there is.

for now, i'll end up using a 3" -> 2.5" transition at the compressor inlet and running some kind of an air filter.

going to get a few hours of sleep here, and back to the garage. i want to at least start the car today, after making an oil return fitting work.

once it idles, i can scope out some inputs at the harness and start wiring up the fuel controller.

here's the short video:


update on progress is coming shortly.

now that i can think again. onto the update.

compressor inlet pipe comes up here, you can see the air pump blockoff plate there.

oil line runs like yay for now, i'll most likely change it and put a pressure sender there. still not 100% on what instrumentation i want to put inside.

cold side intercooler piping:

what the hell is this sensor ? passenger side front air dam/brake duct/underbumper thing, on the other side around the same spot is the outside temperature sensor, but what is this thing ?

exhaust is almost finished. i took the Y pipe from my supra's old exhaust system and made it fit here:

it's a 2.5" inlet going to 2x 2" pipes

more exhaust goodies. i will use the 2.5" flex section, don't think there's a place for the 2" flex sections anymore though. the 90 degree u-ish bends are 2.5" and will be used to make the rest of the exhaust.

once exhaust is done, i'll be able to really check this thing for leaks and see if i have to rig up a scavenge pump for turbo oil.

i was just able to source some injectors for this. 4x 780cc going into my high boost sentra, 4x 660cc coming out of the sentra, and being added to 2 more 660ccs i have laying around, so fuel won't be a problem once i actually need it ( once ms is installed). enough fuel to blow myself up pretty nicely.

i need to read up further on the DISA in the intake manifold and see if it makes sense to trigger that based on boost via the MS. And see if i can take over vanos in a on/off fashion, i.e. more overlap below certain pressure, etc etc. This might not be possible, as i still need to keep the stock ecu happy enough for it to do ignition timing. This is more just thinking ahead.

In this mess of a manifold, what's an easy way to get manifold pressure from the hoses sticking out without actually pulling the thing off the head ? This would be so much simpler if it was a bit more roomy there. The vac routing diagram on the bottom side of the hood is worthless, maybe realoem's manifold drawings will help some.

anybody know if the brakebooster has TWO check valves ? that would be ideal place for a vac source for me.

antifoulers is how i've fooled other odb2 systems, but who knows here.

i'm also not looking to make this 100% cel free thing, it just would be nice.

finished up the exhaust piping, it all fits and such.

now the real fun begins:

going to tie the oxygen sensor signal wires together, and tie the spare ones out of the way.

bank2 short term trim was 0 and state was in open loop (but fault). i.e. no sensor

there was long term trim as well on bank2. i want to see it work both banks off the same sensor for now. just experimenting here, i won't be needing the stock fuel metering stuff soon. once the sensors are tied together, i'll pull the intake manifold, sort out all the vacuum stuff and start on the megasquirt wiring.

after tying the oxygen sensor together:

no immediate codes detected. remains to be seen.

i think the oil return is not doing so well, so i'm going to see how i can get the scavenge pump up and running here.

picture of all the exhaust and oxygen sensor tying are coming up in a few hours once I'm done with the intake manifold and all the vac routing.

after finishing up the Y pipe to the stock exhaust, this was the missing piece:

flux core welding

vband side:

this is the piece installed:

gaggle of oxygen sensors, will eventually get some antifoulers for the """"rear"""" sensor

engine bay shot in progress

tying the two oxygen sensors together:

taped joint is rear sensors, soldered and bare are the fronts:

i then moved onto the intake manifold, figure it could probably use a good cleaning, idle valve could use some cleaning and just checking over around that area.
stock injector clips are ****ing stupid:

on the right is the stock clip, on the left is the same plug pattern with a proper wire spring thing:

stock injectors and 660's floating around in thing of seafoam

ended the night entirely pissed off cause the intake manifold was resisting removal. i may have left out a bracket that's nowhere to be seen, so i'll try again tomorrow

hmm, could this explain why the bavauto power programmer thing wouldn't work for me ? i bought it a while back before i was going to mod this thing. it never worked, so i just kinda left it laying around.

Wow....an '04 325 with an MS43 ECU? I never expected that....that explains why you have narrowband oxygen sensors.

I just checked realoem.com, and apparently all 325xi up to 03/2005 production had the MS43 ECU. Ironically enough, the non-xi vehicles are listed to have either MS43 OR MS45. Gotta love BMW :)
So if someone went with an aftermarket tuning(standalone) can you use the stock O2 sensors to get AFRs on non narrow-band sensors like those on MS45? Doe the narrow-band sensors report .0 to 1 to DME versus 0 to 5 as it would on a wide-band signal? I how i worded that correctly.

wideband o2 sensors do things a bit differently and require a controller. the question is also why not get a proper wideband that you know can be trusted.

more hardware:

tilton diff cooler pump mounted on a big piece of aluminum that was cut out of the crashbar

mount it there-ish

drain from turbo:

goes into that handy oil drain right around the dipstick area:

i will most likely pair the scavenge pump via relay with the fuel pump relay and let that decide when the scavenge needs to run.

next up... making an elbow to go from the throttle body to the rest of the cold side. that's going to happen tomorrow.
as well as plugging the vac source for the oil/air/water separator jobie that goes on top of the manifold

620 Posts
That hockey puck looking ojbect is the temp detector for the headlight wiper washing system. They cause the headlight washers to heat up in cold weather prevneting freezing..... Great job!!! Love to do the same to mine.....

31 Posts
I lurk through these F/I threads on a daily basis, rarely posting, and all I have to say is wow. This got me reallllly excited and I don't even own an E46 anymore. Awesome project!

284 Posts
Discussion Starter · #16 ·
dude. nice choice of car to start with (minus the auto :p) that is an impressive amount of work! I can't wait to see what else you do with the car.
i wasn't even going to modify this car (have 2 other turbo project cars - 94 twin turbo supra, and 04 turbo se-r specv) , ever, hence the auto. but then i started looking at how easily it would be to put a kit together for it, and it really didn't turn out that bad, i already had the turbo and all the fittings, scavenge pump (which is being replaced by an RSR racing proper gear pump once that arrives), 660 cc injectors, etc. just had to get several other basic parts and put it together.

tuning it to run close to stock is going to be the real challenge here.

367 Posts
some serious elbow grease went in to this project, congrats! Always great to see the people ballsy enough to do a kit maker's work themselves

1,205 Posts
Wow dude I missed most of these photos and didn't know all the hard work you were doing.
really looking forward to phase 3 or 4 can't remember LOL Good luck

Legendary like a schoolboy
6,339 Posts
5 star worthy on just the garageful of pictures and elbow grease on the first page.

I cant wait til I can start clicking on the 2nd page though. THat loading to read the last few comments on the 1st page s killing me!!!

good luck on the ebay turbo.

this beats the airplane on the thread mill thing fo sho by like a million.

in for [email protected]

870 Posts
:thumbsup: amazing amount of work! This is incredible.
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