EZL Timing Trouble

[garymand]

I'm new but I've had benz's since '70. Problem: my 90 560SEL idles in park at 950 rpm with timing at 20 cold and goes up to 30 as it warms up. Goes up to 40 as rpms are rev'd.

Car just failed smog due to this but it passes the gas test easily and runs great. Got to get it to TDC to pass smog.

I've checked the dist, timing chain, and EZL. Dist is right on #1 with mark on 0 and cam lobes up on #1. I think I changed the chain two years ago when I had to pull every thing to change the water pump.

EZL seems to work right with the vacuum off but not with it on, It responds to the vacuum but cannot get timing below ~30 idle in Park

Vac off: rpms drop, timing drops to 6-8 btdc. Pull R16 rpm up and timing up to ~16 btdc. Short r16, rms drop low, timing drops to 6-8 atdc.

Vac on: Shorted R16 rpms at ~950, timing ~30btdc. r16 in, same, r16 out, same. Maybe 5 degrees difference max.

Seems like the vacuum is pulling it too far. Help Please.

:(

[jnenad16]

r16 wont make much difference unless you get the one that retartds it 12degrees. as for your original problem, sounds like the pressure switch in your EZL/EZK is out. you could get it rebuilt for about $500, I know of a few places in the stated that do it.
www.4mercedes.com
www.directauto.com
these are just a few places that rebuild electricals. if they cant do it, then you'll need to contact dismantlers like:
www.pgauto.com(east coast)
www.peachstreetauto.com(west coast)
good luck

nenad

[garymand]

I think you have it. Wow, 500 for a rebuild. thanks I need the resources you listed. much thanks.:bunny:

[garymand]

A real learning experience, not sure I've learned the real solution though. I've found that R16 sets the timing without vacuum. Old school says set timing with vac off. I set it to TDC, R16 is about 300 ohms with a variable resistor. R16 can not give continuous change in timing, only 5 steps: -5, 0, 5 (advanced), 10 and 15 all approx. When I connect vacuum to EZL port, timing comes up full vac advance: on mine at 950 rpm, 30 degrees!

Cleaned the Idle air valve and plugged the bypass to reduce idle air. That dropped idle to about 850 and timing to about 20.

Panel Vac gauge is pegged so vac is very good, but still could have a leak.

Adjusted mix: turned CCW 1/4 turn and got idle down to 800 timing 15. Another 1/4 got me to ~700 and 12 advance. Just to be sure went 2 more and got idel down to 600 irattic and stumbling. Went back to original and returned to the 1/2 turn CCW, 700 but timing is still +12 with vac on, 0 vac off.

checked duty cycle with ac volt meter: started at ~5.0 V about 60%? w/ 1/2 turn CCW = ~4.1 or about 70%

found http://landis.com/mixture.htm he describes a 91 560SEL, X11 and X92. My 90 is different and I wonder if this is a clue: X92 doesn't blink. It comes on when the button is pushed with motor running. motor off, ignition on, LED is lit, button does nothing.

Help I don't think I've fixed this yet because the vacuum timing is still 12. Is this wrong and timing is fine? Smog guy should pull vacuum to check timing?