E34 520i ~ 18mpg ! Hose help and more :)

[matrix179]

Hi , New to the board and hoping someone can help..

I recently bought a 92 E34 5201 after my Toyota Celica vvti basically blew up..

I was lucky enough to get hold of this old beemer girl but she has been neglected for at least a year if not longer ( had been standing for over a year ) She only has a genuine 106,000 miles but due to neglect although a cheap buy I am having to replace bit n bobs and chase problems....

I have one big problem that is leading me to chase another..

basically faults are as follows:

1. Only achieving 18mpg !!! yes 18 mpg
2. Rough idle ( car rocks ) when its in Park or neutral when hot...rough idle is a drop in revs now and then then a pick up..Hunting
3. Smells like she is running rich but have to floor throttle to get her started from cold.


i have already replaced sparks, oil and oil filter, air filter..

I know some issues could be idle control valve, and im planning to give this a good clean with carb cleaner shortly..

The main issue I have in slowly problem solving at the moment is that im sure a lot of the mpg and rough idle issue is connected to vacuum hoses..

I know 100% for sure i have a cracked hose with no clip or clamp ....the one that comes of the main inlet pipe between MAF and throttle body and goes to the ICV.

I also have a bizzare almoost laughable pipe i need to sort..

On the crank case at the front ( Rad front and same side as oil filter) I have what can only be described as a piece of yellow garden pipe ( yes garden hose pipe !) lose and unclamped on this location . It then dissapears under the inlet manifold????

i have an old version of a BMW Tis , a pdf version of Bentleys acces to OEM parts and always search by my Vin njumber for accuracy...whats worrying is on the shematics it looks like the correct hose T's shortly after coming out of the crank housing cover?? to where I dont know...same on TIS ..it shows me it splits to a T and should even be a bracket there...all schematics never show where the hoses go....


any advice about vacuuum hoses or where i can find a schematic of original to and from engine bay locations would be SUPERB..

or does anyone have a similar E34 that they could have a peek and report back to me...


Will try to take a pic in a few days to help....you will wet yourself!!

PLEASE HELP

[Ferret]

Agree with whiskychaser, loose/cracked hoses cause massive misfires on these engines... try unplugging the MAF and seeing if the engine suddenly goes smooth again :)

Hoses are not expensive from the dealer usually... find any that even look suspect and just bin em :D

It'll give you a lot of good smooth service if you do this!

[whiskychaser]

Vacuum leaks will definitely cause it to run lumpy and affect your mpg. If you dont know this site already have a look - you need last 7 digits of your VIN:
http://www.realoem.com/bmw/
That will show what parts you SHOULD have :)

[Morgenster]

Does the garden hose connect to the dipstick guide tube? if so it's not that a big deal if it's snug. I'd definitely check out the ICV connecting hoses (especially the elbow hose that's so hard to reach).
Mine gets about 9l/100 km but I drive pretty hard.
Like Ferret said: these engines go nutty if there's the slightest vacuum leak.

[matrix179]

thanks guys...yep vacuum leaks are a nightmare....

i have tried real oem before but like BMW TIS it only shows parts and not where they connect to, so good for getting parts but not helpful for final location ( only a problem here as i cant follow this yellow pipes route as i think its a bodge job) .

This yellow pipe dissappears under the inlet manifold but will attempt to trace location and take some pics for novelty value..

The suspect pipe that joins the big bore pipe between MAF and throttle housing is def on my shopping list .

Tried unplugging MAF....runs very very smooth then engine slows and threatens to stall.....