SWAP Thread: '91 325i Sedan - S50b30us

[cmybimmer]

I can imagine the frustration.. But its all in the past now. Time to go for lots and lots of joyrides!

I want s50/s52 power now :(

[hwy84]

24 valve/4 door mafia?

Thanks, and you're right - I owe this whole swap to the power of a cheap no-name headlamp, and the heat of burning frustration/rage that kept me warm under the car in 30 degree temps when I was swearing at bolts and wires and reversed fuel lines. ;)

My kingdom for a garage...

Looks like the Norcal 24v/4-door Mafia is all assembling in this thread! Sedans FTW!

[cmybimmer]

Congrats!! And i'd hate to be working on a car with this chilli weather andd such short days. I was working on my swap during the summer and the 15 hours of sunlight in a day seemed to fly by :rofl:. Props :up:

[hwy84]

Good to hear of another s50 4door in the bay!

Congrats on getting her running!

Thanks, man! Now... Smogging. Hopefully this will go smoothly.

Gotta love California!

[Danny]

Good to hear of another s50 4door in the bay!

Congrats on getting her running!

[hwy84]

Holy crap!

IT RUNS! Sweet sky above, it RUUUUUNNNSS!!!!!

Turns out the stomp test code had nothing to do with anything and was a big red herring. I pulled the fuel pump relay, jumped it, and listened to the pump (with the back seat off) and I could hear it spin. Knew then that the pump was good. Quintuple checked my wiring, and I was confident it was correct.

What's left to check when all the electronics call for fuel, and you get no fuel? That's right. The fuel lines.

Yup. I had reversed 'em.

Put them the right way, and the "M Crap" started right up, stumbled for about 20 seconds, and then just settled into a nice smooth idle. (A very angry idle, since I only have the center section installed right now, and no muffler. Actually sounds awesome.)

So yeah. That's it. You gotta love when your car keeps you humble. It's like I was getting too cocky, and my car said,

Sure you can study the ETMs for 3 different cars, and make a wiring harness that works, and do all the other thinking crap that goes into this swap... but F you. You'll screw SOMETHING up.

And the car was right.

But I just don't care. I am so excited I could just about die. In fact, I may die, since I am currently covered in gasoline... Pulling the reversed lines off the rail sent a gallon-sized money shot of high pressure gas all over me.

Off to the shower.

Thanks for the help r3v!

[hwy84]

FPR vs. FPR

Ha, yes. By FPR I meant Fuel Pump Relay, even though I typically mean Fuel Pressure Regulator. Apparently now FPR = Feeling Pretty Retarded.

In any case, thanks for confirming. I'm pretty certain I jumped 30 and 87 (based on the numbers on the relay pins), and got nuthin'. I'll move on to fuses and then directly to the pump next.

Thanks - and keep the suggestions flowing, I am all ears!

Oh - and thanks for the 4-door props... but don't congratulate me yet! I'll feel worthy of congratulating when the thing moves under its own power. :curse:

[Adrian_Visser]

Sorry you say you jumped the FPR?

FPR is an accepted acronym for fuel pressure regulator But I'm going to assume you meant fuel pump relay.

Jumping it, assuming you jumped the correct terminals (30 and 87) on the relay should make the fuel pump run. Obviously this is done with the ignition key in the Run position.

If not check the fuse and then check for power at the fuel pump.

Oh and congrats on the four door, I'm going to be swapping my s52 drivetrain into a '91 Delphin 318i four door in the spring as well.

[hwy84]

Well, damn.

So I got the correct chip (found a used Dinan chip for a stock S50) and got the engine in and wired.

Sadly, I have a "cranks but won't start" situation now. I tried last night, and my battery was very weak. Thought it might catch - it didn't. I have charged the battery now, but no change in behavior. Here's the deal:

• When I turn the key to "on" I hear humming, I get the dash lights (including CEL).
  
• Stomp test works, and gives me 1281 - which is DME memory. Typically caused by low voltage... but I have good voltage now - reads 12.03 volts at the distribution block.
  
• DME is grounded.
  
• I swapped in a second ECU, with a second chip - no change, same 1281.

I am fairly certain I am not getting fuel, even after I jump the FPR. I can't hear the fuel pump whine, and I smell no fuel. Fuel pump is new - was replaced and running shortly before I started the swap.

If it helps - when cranking, the engine has a distinct cranking pattern, not just a steady rhythm of "turn, turn, turn, turn, turn" but more of a syncopated, "turn turn, pause, turn, turn, turn, pause" that repeats. Maybe typical, maybe weird.

I am an electrical newb, but I studied the hell out of the ETM to get my harness right... my swap chart is below.

I am going to check the Cam/Crank position sensors to make sure I didn't get them backwards, but I am 99% certain that is not the case.

Also, the harness grounds (2) are grounded, motor is grounded to the chassis on driver's side mount arm, coils are grounded to valve cover.

Harness power (1) is connected to dist block, as is chassis power from the battery (2 - big and small) and from the driver's side firewall (2 medium and small).


Function 1991 325i C101 12/93 E34 X20
alternator 1 25
oil level sensor (static) 2 1
coolant temp sender 4 12
oil pressure switch 5 23
power distribution box to O2 relay 6 22
ignition switch 7 21
fuel economy gauge 8 24
engine speed output 9 20
oil level sensor (dynamic) 10 2
SI RESET 11 19
check engine light 12 8
fuel pump 13 13
speed signal input 14 14
starter (unloader relay) 15 15
Diagnostic 16 17
starter (power during start) 18 18
ABS 20 3

I have to run to work, but any thoughts are welcome. Thanks all.

[scottinAZ]

I moved my STOCK e30 325i booster. Exactly .5" to the driver side. Clevis was dead easy to put onto the pedal arm, but installing the pin was a PITA.

QUESTION TO THOSE RUNNING THIS BOOSTER SETUP: With the booster shaft now at a slight angle - have you run into any binding issues with the booster?

I know there is a fair amount of play in the mechanism to allow for the change of angle as you depress the pedal, and so far it feels smooth, but I want to make sure I haven't set my self up for something... unexpected.

Pics to come.

Nope, no binding or other issues with a relocated stock booster. feels just like it did before the swap.

[hwy84]

Thanks for the replies!

Been out a while, but thanks for the replies about the MAF. Gotta get the right chip. (or a 3.5" MAF). Damn.

Lots of progress though: Engine and 260 are in the car, mounted, and driveline is all connected.

PROPS: To White325is His 260 trans bracket was PERFECT in every way. I used the early 320i mounts (p/n: 23-71-1-109-173) and everything bolted up like stock. The bolts on the mounts JUST fit through the slots in the bracket (I screwed the mount through the bracket) - but they do fit. And it's awesome.

Next issue: (Yes, I searched, but didn't find the specifics...)

I moved my STOCK e30 325i booster. Exactly .5" to the driver side. Clevis was dead easy to put onto the pedal arm, but installing the pin was a PITA.

QUESTION TO THOSE RUNNING THIS BOOSTER SETUP: With the booster shaft now at a slight angle - have you run into any binding issues with the booster?

I know there is a fair amount of play in the mechanism to allow for the change of angle as you depress the pedal, and so far it feels smooth, but I want to make sure I haven't set my self up for something... unexpected.

Pics to come.

Next up - stock S52 Manifolds to Stock S50 center section. I think it's time for the BFH...

[Mr.SWISS]

If you are tuned for 3.5 MAF. you have to run 3.5" MAF sry.

[cormier]

Why don't you just run the 3.5?

Swap lookin great man mines in progress too! Love the red ps

[hwy84]

...And the questions begin

Tune Question:

I came across a free Turner (Conforti) chip tuned for a 3.5" MAF only, and extended rev limiter.

I don't have a 3.5" MAF - I have a stock MAF.

My Q: For a given volume of measured air, will the voltage from the stock MAF be different from that of a 3.5" MAF?

I know a 3.5" MAF could theoretically flow more air, but I am hoping that the stock and 3.5" MAF will output the same voltage from idle up through the volumetric limit of the smaller MAF.

If that the case, I assume I could use the chip with the stock MAF, and it basically would be like running a stock tune...

Wishful thinking?

[hwy84]

Nice! I just (mostly) finished a similar looking build. Red '89 four door with S52. I love it, especially the fact it's a plain old looking four door! Good luck!

Thanks, and congrats on competing your swap!

I am looking forward to enjoying the "Stealth" factor on this...