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My engine is at a high idle (2500 RPM), and I'm preparing for the tune up.

I have a few sketchy vaccum hoses that have electrical tape around them making me think that my high idle could be a combination of:

-neglected valve job
-cracked vaccum hoses
-poorly adjusted AFM.
-ruined/broken sensors (Not sure what sensors are on an L-Jet model, I can't even find the TPS, if I have one!)

I"m also at 1 mile in altitude where I live, so that could play an issue with my tuning.

In anycase, can this forum help me with:


1- A drawing or picture of an M90 and what sensors are on it and where?

2- A place where I can get vaccum hoses part numbers for a euro-spec engine. On the US part supplier website, I only get a choice for a 633Csi and that comes with all the nasty vaccum lines for the old inefficent smog controls.

3- Any other tips fighting a high idle.

Thanks.

Will a pic of my 81 EURO spec M90 help? I used 1/8 in U.S vac lines on mine. I think its only 2, I have no smog or emissions .

I would fix the lines , then set the TPS and see what happens.

I think with out looking at mine the Vac line starts at the fuel REG then Ts to the intake and the big black air intake hose to the fuel valve body.

I just sent a note to Bob he has had his 80 euro for next to forever, he sent me a picture of the vacuum hoses a few years ago but I can't find it. Hopefully he will see this and post some pictures.

Here ya go fellas, but please keep in mind that my 6er is actually a US model, vintage 1980 :?

BTW, you do have a TPS and it's located on the back side of the Throttle Body itself. Should have 2 pairs of wires going to it, as there are 2 switches on the TPS. One is for idle position, the other is for WOT, the serious go position

GRNSHRK wrote:Here ya go fellas, but please keep in mind that my 6er is actually a US model, vintage 1980 :? :

A thousand lashes oh mighty great one!!

BTW, you do have a TPS and it's located on the back side of the Throttle Body itself. Should have 2 pairs of wires going to it, as there are 2 switches on the TPS. One is for idle position, the other is for WOT, the serious go position Wink

How does one set the TPS?

With mine I just turned the ignition on then losend the screws to TPS and moved it back a forth until I heard a CLICK, and that was all there was to it. Oh tighten the screws back down when its set.

"AFM" is French for "Leave It Alone!". There really is nothing to adjust in normal usage. It should be absolutely the last thing you fiddle with, and then only after you've eliminated everything else.

There is a Throttle Bypass Screw on the throttle body and there is an Auxiliary Air Valve.

540i wrote:How does one set the TPS?

Below is a link for an excellent article from the FirstFives Tech Library, on the adjustment of the TPS and the Throttle Body with some references to the vacuum lines connected to it:
http://www.firstfives.org/faq/throttle/throttle.html

(Photos from FirstFives)




Here is the article on the Auxiliary Air Valve adjustment and it's hoses:
http://www.firstfives.org/faq/aux_air_v ... valve.html

Here is an L-Jet Seminar in PDF on the layout and function of the system:
http://www.firstfives.org/faq/ljet/jetronic.pdf

Wiring diagram of the L-Jet:
http://www.firstfives.org/faq/ljet/528i ... ematic.PDF

540i wrote:A place where I can get vaccum hoses part numbers for a euro-spec engine. On the US part supplier website, I only get a choice for a 633Csi and that comes with all the nasty vaccum lines for the old inefficent smog control

There are 3 online parts catalogs, and they all list the Euro parts as well:

RealOEM.com, the original and I still find it the fastest to navigate if you are still on dialup:
http://www.realoem.com/bmw/select.do?vi ... E24&arch=1

BMWFans, more graphic, so slower for dialup, but if you click on the part number in the right hand column, it will show you all of the other cars the part was used on. Very handy for hunting at the salvage yard:
http://bmwfans.info/original/E24/Cou/

Maximillian Importing, they will sell you the part, but the price isn't much better then the dealer:
http://www.bmwmobiletradition-online.com/bmw/


For parts you will need to look up the part numbers for your Euro and then do a "Search by part number" at places like:

http://www.AutoHausAZ.com
http://www.Pelicanparts.com
http://www.BavAuto.com (Great Catalog, order it, it's free)[/quote]

I temporarily fixed the idle.

I tried fiddling with the TPS "set" switches and it didn't do anything. So I looked over some diagrams on first-five.org and decided to play with the idle bypass valve.

I screwed the valve out all the (at least I think it was that), and fired up the engine and it was speeding at 2200-2300 RPM. screwing it down didn't do much until the VERY end when I chocked it off. When screwed down as tight as it will go, my idle is at a healthy 1200 RPM.

It was cold out, and the engine would "miss" or hesitate occasionally at this low idle. This could be a secondary problem, as the engine coolant was cold and a poor aux-air valve is messing up with my intake air and fuel/air ratios.

My guess is, is that I have a serious or multiple minor air leaks somewhere even though I can't detect them from the hoses. Should be a fun -not- project this summer.

Oh, on a side note, I noticed some audible tapping sounds coming from the rear of the engine. Sounds like a valve. Hopefully it's not serious, my guess is the spray-bar banjo bolts are gone as I seriously doubt the PO did anything about it. I'm praying a head rebuild isn't the order of the day.

I would adjust the valves and start over again. You might have some valves out , it will run like crap if they are out of adjustment.

GRNSHRK wrote: ↑Thu Aug 13, 2009 7:12 pm Here ya go fellas, but please keep in mind that my 6er is actually a US model, vintage 1980 :?

BTW, you do have a TPS and it's located on the back side of the Throttle Body itself. Should have 2 pairs of wires going to it, as there are 2 switches on the TPS. One is for idle position, the other is for WOT, the serious go position

Bobbo,

the document is gone

2- A place where I can get vaccum hoses part numbers for a euro-spec engine. On the US part supplier website, I only get a choice for a 633Csi and that comes with all the nasty vaccum lines for the old inefficent smog controls.

this place has OEM vacuum hoses,
https://www.belmetric.com/braided-metri ... -c-14_138/

Hefeweizen wrote: ↑Mon Jul 02, 2018 7:24 pm

GRNSHRK wrote: ↑Thu Aug 13, 2009 7:12 pm Here ya go fellas, but please keep in mind that my 6er is actually a US model, vintage 1980 :?

BTW, you do have a TPS and it's located on the back side of the Throttle Body itself. Should have 2 pairs of wires going to it, as there are 2 switches on the TPS. One is for idle position, the other is for WOT, the serious go position

Bobbo,

the document is gone

Or in other words, does anyone have a vacuum diagram for a M90 L-Jet?

Sorry gents, took the week off and stayed FAR away from the computer

Okey doke, repost of the vacuum photo and description, again this is a US version M30B32, not M90

And while these mills are quite different, I would doubt that the vacuum connections would be