Small things I need help with on my E28 m20b20

[byterrr]

OK, today I was replacing my distributor cap and came across this hose (air hose?) which was knocked loose. This coincided with the car having a high idle starting at about 800 rpm and raising to around 2800 rpm within 10 seconds. Can anyone identify where this black and white hose should connect to?

[tn535i]

I don't think the white strip is original... but no matter... just a guess looks like the right length for the FPR on the front of the fuel rail. If not that one of the emission related hoses.

But do I see your distributor way down low... I've never seen that motor, even in pictures. And there appears to be a vacuum advance dash pot on the side... another possible point for that.

You could plug it to see if the idle goes back down, then figure it out.

[byterrr]

This is an early 520i which has the L-Jetronic system and has a regular distributor tucked away to the right side of the engine. It has its share of issues and having a less common variant can be challenging when it comes to diagnosis and repair sometimes.

Which part is the vacuum advance? I'll investigate it further

[duggi]

I have these two photos of a known-good L-Jet 320i (e30) for reference. Sorry I don't have one from the other side...

[byterrr]

OK so having traced the hose over the top of the engine and under the intake manifold I arrived at a T connector

One side of the T connector leads into the intake manifold and the other into some sort of valve (both have a light blue stripe)

[byterrr]

I have these two photos of a known-good L-Jet 320i (e30) for reference. Sorry I don't have one from the other side...

The black wire with the blue stripe appears to be visible in these pictures although in a slightly different location and sans the black wire with the white stripe and T connector (unless these are not visible due to resolution

[JohnH]

You may find this diagram useful


Its from Haynes manual 1560.

They describe it as L-Jetronic, but as we know its really LE-Jetronic and LE2-Jetronic from about 1986 onwards.

[byterrr]

OK, the location of the connector for the hose has been found!

For future reference the T connector is detailed in this diagram and connects to the distributor (figures 5 and 6)



This appears to only be fitted on cars which are sold in Australia and Switzerland.

Since reconnecting the hose the car now settles at idle at a lumpy and uneven 1200 rpm which is higher than usual but a big improvement over the 2000 rpm.

Would this be a vacuum leak somewhere or any other suggestions?

[tn535i]

A vacuum leak could mean unmetered air and it is also running lean, so yes possibly. When you changed the cap did you do anything to the timing or move the distributor? I'm not familiar with this motor but remember the old days with points, condenser and vacuum and centrifugal advance systems. Others might know if it could be something related to any of this but generally that would result in a slower and labored idle if altered.

If you have a vacuum gauge it's usually a good quick check and at idle I would guess your car should run around 20" Hg.

[byterrr]

I don't have a vacuum gauge but I'll work on getting one and giving it a try

[byterrr]

Video of rough running. Does it sound more like a vacuum leak, timing or something else?

https://www.youtube.com/embed/MQn8iE-0ezE

As a bonus, some sort of new engine oil leak seemed to have occurred when I started it today. Smoke was pouring out from where oil was hitting the manifold (I think) and is visible on a puddle on the floor.

https://www.youtube.com/embed/o8FlujT7uN4