Mystery Vacuum?

[wildeian]

Any body got any ideas where this vacuum pipe connects to?
Just swapped the engine (M20 325i sport) and my old one doesn't have this!!

Blocking it off causes the engine to hunt, but it is idling a bit rough as it hasn't been started in over 6 months.

This engine used to belong to Buster, but I haven't been able to contact him to find out what it is.

(Blue pipe goes to fuel regulator)

Any ideas Guys?

[Ant]

needs blocking off dude, only external vac source is the FPR, you may need to ajust the idle CO as it will go rich once that unmetered air is taken out of the equasion,

Tune it by ear with 5mm allen key in AFM, so it idles solid , then get it checked using an emissions tester just to be safe, not sorry.

HTH

[wildeian]

Cheers Ant,

Time to get my baby back on the road!!

[buster]

Hello Ian,i hope you got my PM,if not then that pipe was connected to a vac gauge.I was planning to turbo charge it so i was going to connect the boost gauge there.Just block it off or fit a new one off any 320/325 engine which has one pipe on.
That one came off a 525e.I thought it looked a bit better than running a T peice into the fuel reg vac pipe thats all.

It will run rough until the ecu adjusts also.Did you get the ecu with the engine or not ?
If you did then it has a zone chip in it,the car shouldn't need the AFM tweeking as this had been checked when i had it and theres no reason it will have changed.
Standard ecu or not,it still needs to adjust to running the 535 injectors.It will need to be left idling for about 20 mins,then a 10 min drive and it should be ok.This happens when the battery has been off for a while,the ecu needs to set the duty rate on the injectors.It will run rough and probably stall a few times until it starts running right.You will hear it change its idle speed until its right. Ant will varify this.


cheers
andy

[Globulator]

My M20 only has the one - connected in yours to the FPReg via the blue.

FYI The regulator uses it to reference the fuel pressure between the fuel rail and the manifold, so the injectors squirt in the right amount - 'coz the injectors are also between the rail and the manifold.

Not sure if the extra hole would act like the ICV is more open (and therefore the ICV will compensate) or if it will raise the pressure at the take-off so the FPR will be fooled into providing too much fuel pressure as it thinks the manifold pressure is higher than it really is.

[buster]

that pipe is just causing an air leak.It has nothing to do with the lumpy running.Its the fact that its running 535 injectors and the ecu needs to reduce the duty cycle on the injectors,it will do this but it needs to be ran as i said before.It does need blocking off though.

[wildeian]

Cheers Globulator.

Yes Buster, I did get the Zone chipped ECU, but I haven't fitted it as it is different to mine.
My 325i sports ECU has the 35 pin (2 rows of pins) connector which I believe is the earlier Motronic version, than the 55 pin (3 rows) that came with the engine. The ECU is also about half the size of the new one.
(I don't understand why I have the older version, as the car a 1990 and would of been one of the last??)

I do have the loom though, and I was going to change it, but the new loom has a battery neg terminal on it for an engine bay mounted battery, so I wasn't sure if it would work. (Or if it would be as simple as just changing the loom)

Any ideas?

[buster]

fit the whole loom,the batt terminal goes to the + post on the bulkhead infront of the driver.Your car shouldn't be early ecu type.Is it a convertable ?

[wildeian]

No, Its an Alpine white 325i sport, I believe it is a limited edition