Another Idle Problem

[Shava]

Hi everyone
Greetings from Portugal!

I need some help figuring out how to fix the odd idle problem on my 85 320i.
First i can´t find anywhere a clear reference to my engine. I think it is a LE-Jetronic but every forum or site i read about it talks about an Idle Control Valve which i don´t have. It has chrome bumpers though...;D
From what i can see there is an auxiliary slide valve that i took off and tested and it slides according to temperature just fine.

So, now the problem... on cold start the engine revs up to 1500 for a few seconds and the drops almost to stall, then the vacuum valve near the throttle revs it up and it stays on 1500 a few more seconds and drops again...on and on until the engine warms up. Then the idle is fine.

Vacuum leak? there´s a ton of vacuum hoses around...
I´ve played with everything i could from the AFM to the idle stabilizer valve (above the valve cover) to the vacuum valve but couldn´t figure out any combination that worked.

My engine is basically this one:


But the 320i one.

Thanks for any help and best regards

[dnguyen1963]

Do a smoke test to find vacuum leaks.

[Shava]

Hi dnguyen1963

Has for the smoke test, i don´t have any shop that does it around here. I might try a Bossch Service shop but i had enough with mechanics that only know how to plug a PC to a car and read whats on it... and has you nkow these E30 don´t work that way...

After some checking i found that the hose that goes from the valve cover to the throttle body was cracked. Fixed it and now my idle when hot is too damn high.

If i open the oil cover on the valve cover the rpm come down.

What i need is for someone to tell me a few basic settings since i´ve tampered everything i could find

How should i adjust the throttle stop screw (i dont know if what i have is a TPS or not but even if i unskrew it all i don´t hear any click and if i disconect the plug beneath the throttle housing nothing happens).

On average how many turns should i give counterclockwise on the AFM when fully screwed clockwise?

How shoul i adjust the idle stabilizer valve above the valve cover?

And finally whats the basic setting of the vaccum valve screw that pushes the throttle lever?

Thanks again for any tips anyone can give me

PS - If i clamp one of the vacuum hoses that goes to the throttle body the engine stalls. I think that indicates that i have no leak because if there was one the engine should keep working. Or not?

[dnguyen1963]

Ok, don't do anything else, yet. You can make your own smoke machine for cheap. Do you have an air compressor? If yes, then you are all set. Follow this link to make your own.

http://www.r3vlimited.com/board/showthread.php?t=274418

You have to eliminate all vacuum leaks before search for other problems.

[Shava]

AWESOME!!!!

Thanks i´ll give it a try.

[Shava]

Anyway just a thought... if i take off the oil cap and the RPM drops, doesn´t that mean that there are no vacuum leaks?

[dnguyen1963]

The opposite...it means that you have a big vacuum leak somewhere.

[Shava]

Shit...

[Shava]

Hello fellow beemers

Well i found another hose that seemed to leak.
Fix it. The idle is now even higher.
Despite that the the idle when cold is now steady at 1700.
But when the engine warms up it keeps that RPM.
If a take any of the vaccum hoses off the RPM drop.

I´ve tested the air slide valve and its working has it should.
The throtle stop screw is not touching the throttle lever.
The idle adjust valve screw is fully closed.
And the AFM who knows... but its like 8 turns anticlockwise.
TPS doesn´t click but i think it never has, even when it was running just fine.

This is starting to make no sense to me. If i simulate a leak taking a vaccum hose off the RPM drops quite a bit.

The car starts immediately cold or warmed up though...

HELP!!!

[6A LDY]

You can test for leaks with just a cigar and a piece of extra hose.

How much have you messed with the settings(tightened loosened screws)?

Does it seem like the throttle sticks at all or isn't closing all the way?

[Shava]

Hello 6A LDY

Thanks for the reply.

I´ve messed a lot but knowing what each part does (AFM, throttle screw, vaccum valve, idle adjust valve). So i can adjust fairly correctely again. My worry is that as the settings are, the car should idle very very low and not at 2000 RPM.

I´ve tested with the cigar and haven´t found any big leak in the hoses that justifies the behaviour that it had.
Anyway i saw that the hose that comes from the valve cover to the throtlle body was cracked where it clamps.
After cutting a bit and attaching it again the idle became very high.

I don´t know what else to do.

Thanks for any clue...

[Shava]

Well... it went straight to a Bosch Car Service this morning...

[raudonis]

I have a 323i from 1983, still running the shit Jetronic.

I guess the problem is, although your thermostat idle valve is opening and closing based on the coolant temperature it opens too much and passes too much air - reason for high idle RPM at least it does this in my car. Simply try to pinch the air hose that goes from the rubber intake elbow to the stupid thermostat idle valve, if RPM's drop significantly - that is your problem.

The reason for 0~1500RPM cold pulsation is that ICV passes too much air, ECU sees that RPMs are higher than idle and the throttle is closed - it thinks car is coasting in gear down the hill and it shuts off the injectors, the RPMs drop, vacuum piston slightly opens the throttle and the cycle continues on and on and on...

Throttle stop screw should be set in a fashion that TPS clicks as soon as you open the throttle - take note that when these engines are off, the vacuum piston keeps the throttle slightly OPEN. To adjust the throttle stop screw, you need to temporary remove the vacuum piston, so the throttle closes FULLY.

The AFM idle screw should be adjusted for hot engine so that there is no more than 1,5% CO in your exhaust gases at idle.

Idle screw on the intake should be set that your hot engine idle RPMs are ~800 +/-50 RPM.

These engines are really sensitive to big vacuum leaks, this is the reason why it stumbles hard when you open the oil cap.

I can make pictures of my vacuum hose setup that helped to drop the idle RPMs, but the best advice is to convert to Motronic 1.3 from a facelift car and remove all those stupid vacuum lines together with the thermostat ICV:

http://www.e30zone.net/e30zonewiki/index.php/Converting_to_Motronic_1.3

better power, reduced fuel consumption, less vacuum line headache

[Shava]

Hello raudonis

Thanks for the reply.

About what you said:

- The car only started to idle high when i fixed the hose that goes from the valve cover to the intake elbow.

-I don´t see any change in idle now for when the car is cold or hot. It would be a great coincidence for the valve to be broken now.

- My TPS never clicked. I passed that information to the Bosch tecnician.

The other stuff can only be adjusted with expensive equipment...analyzers...

So now the car is at the doctor... lets see what they say and how much will cost... hope not to get cheated...

Thanks for the support

P.S. - Coverting to motronic is too much expensive in this god forgotten country

[dnguyen1963]

I still highly suggest that you have a proper smoke test done on the engine. Vacuum leaks are very troublesome with these engines and they must be fixed. Otherwise, you'll throwing money into a bottomless pit.