560 Dist Timing - Page 2 - PeachParts Mercedes-Benz Forum

garymand · #16 12-11-2006, 10:26 PM

Where is the R16 resistor. It must be a variable resistor, so I can dial in the idle timing?

Gary

jhodg5ck · #17 12-12-2006, 08:11 AM

Gary, cam location and is Very important when considering distributor alignment.

The R16 is located next to the fuse box, it is a small (1/2 inch) square box w/ 2481 (I think) written on it. It will also have electrical tape around the bottom where it plugs into the wiring harness. They don't make a resistor big enough to bring your timing back that far so that's not going to solve your problem.

When you are at TDC your rotor should be pointing right about 10:30-100 O'clock.

Jonathan

david s poole · #18 12-12-2006, 10:10 AM

hey guys what about the top dead centre reference sensor at the flywheel[the single pin wire at the ezl]? they have been going bad because of time not mileage.it needs doing so put one in,a little fiddly at the trans end but might cure your problem because the alternative is another ezl[$$$$$]

garymand · #19 12-12-2006, 11:55 AM

I thought there should be a sensor. Is the trans at the harm. balancer? I've seen a little stud stiking up about 1/16" at about 25* on the HB. Thought that might be to cause a pulse.

Wifey need the car for the next 4 hours. When she gets back, I'll :

find R16, I get the impression it is a selectable/removeable fixed resistor
find the sensor (its probably close to the EZL?),
pull the v covers to see where the cams are And chain condition
What is the -100?? (4:30 -100). I thought the distrib could be at either 10:30 or 4:30 (one rotation of crank, exhaust, 4:30. next rotation, 10:30, compression, Wrong?). My rotor was pointing to 4:30.. the cams will tell me ex or comp and I'll put it on compression check chain, and put the dist on #1 (10:30).

Thanks everyone. Anymore ideas??
Gary

garymand · #20 12-12-2006, 11:57 AM

Sorry, I wasn't logged in and missed the flywheel location for the sensor.

Johnhef · #21 12-12-2006, 12:16 PM

assuming the chain hasnt jumped or anything like that you can just look in through the oil cap to see what cyl 1's cam is at.

david s poole · #22 12-12-2006, 04:16 PM

the reference sensor is mounted on the bell housing and has a single ground shielded wire running to a single pin plug at the ezl.

garymand · #23 12-12-2006, 05:29 PM

Still trying to get timing down to near TDC.

EZL sensor measures 833 ohms.

Looked through the oil fill hole: #1 is in exhaust lobes down, 'dizzy' is under center of #6 plug: ~4:30.

Strife · #24 12-12-2006, 08:28 PM

If everything is "right", the cams should be at zero (the scribed lines which you can't see without removing the valve covers), the distributor rotor should point to a scribed line on the body of the distributor, and the pointer on the water pump should point to the harmonic balancer's zero mark. It is possible to get the distributor 180 out of phase, which, incredibly, seems to want to run (terribly).

garymand · #25 12-12-2006, 08:39 PM

Its running great! Passes emissions. Dist is in right. W/vac removed from EZL: R16 works; open 16 btdc, r16 (750 ohms) 6-8btdc, shorted 6-8atdc.

But with vac connected R16 has no effect and timing is at ~22 btdc cold and it goes up to ~30 btdc once warm.

This is all in Park

Thanks

david s poole · #26 12-13-2006, 10:39 AM

i think your missing my point.you say that as temp climbs so does timing and it has been my experience that these sensors go bad with heat.unlike most sensors that just go out these give some warning.

garymand · #27 12-13-2006, 01:54 PM

David, not at all. Thanks to you, I and anyone watching, know about the sensor. I measured it at 833 ohms, but not temp. I'll do that next. There should be a change hot and cold if it change signal as the engine warms (Could, because the change is in a just few seconds, fast like electrical, that doesn't eliminate a circuit in the EZL either.)

Jonathan led us to the EZL, the glories of variable timing through R16. (I can go to Radio Shack and get a little 2.5K pot, put in place of the actual R16 and easily adjust my timing for gas or altitude!!)

But so far, we are 50/50 Sensor or EZL:
A) Sensor is wrong and maybe changes some with temp.
B) EZL is overpowered by Vacuum
C) EZL is overpowered by Vac and temp sensitive
D) My Luck: A&B

It couldbe A&C but no dif in solution.
Can you help a little more? what does the manual say about checking the sensor any measurement values? Do yu have a bad one and a good one to measure resistance. I suspect ohms will not be right if sensor is not giving right signal -but of course maybe not. I ordered the MB CD manual but it willtake a week to get it

Johnathan said he would check the EZL to see how it responds to vacuum and R16.

Sure I can buy a sensor and get it in a few days, but what if its the EZL, or both. I don't have a spare to swap to break this 50/50.

Thanks to both of you and this board!!
Gary

garymand · #28 12-13-2006, 02:24 PM

Strife what and how is the home brew 1st gear start? And Johnhef for the hole trick. That's helped eliminate the mechanical timing. The emissions being so good point away from that too: valves operating at the wrong time or spark at 180 should be knoticable. I thought perhaps dist could be off one tooth, but seems too close to right on. I would think that if a mechanical is causing this: one or both cams jumped a tooth or the chain stretched, it would cause a failure in emmisions. combustion could not be that good to pass nearly perfectly.

What I think I see:
An EZL that without vacuum can get put timing anywhere it is needed at idle, between 8btdc and 16atdc. That seems to be exactly what it should do with the sensor signal and R16.
A sensor that for the most part is catching the tdc at the right time, but I also see a temperature shift.
Both devices could change results with temp, but it is more likely EZL would respond linearly with a gradual shift in timing.

JMO FWIW: I would guess the sensor output would not shift in time but in amplitude (signal strength, amount, value, voltage) Its probably a coil that feels a magnet passing on the flywheel. It acts like a generator and responds with a signwave pulse as the magnet passes. the signal is probably a small voltage 0 to 1V, and that explians the shield on the cable to keep the low voltage signal clean.

If its output changes I would suspect it falls in volts and the EZL looses it in the noise and would respond with a window of irratic timing and sputtering or rough idle.

Lov this stuff,
Gary

garymand · #29 12-19-2006, 11:00 PM

Update: The best I could do with R16 was 300 ohms gave me 0 tdc with no vac. Vac on still pulls timing up to 12. Idle was still about 900. Not sure this is the way it should be, at least its closer.

Got brave and adjusted idle mixture at the air horn. CCW leans so I went 1/4 and got a nice reduction in rpm. It took 3 or 4 of those 1/4 turns (slowly and waiting for stabilized idle) to get too far, a rough stumbling idle. Good news idle came down to about 600 and timing down to 10.

Looked at signal at X11 (I think pin 3) with ac meter and pure rms meter. My scope would'nt trigger on this signal. It would trigger on pin 1 but I think that is tach signal. Voltage started near 5V and came down to 4.1 (about 70%) where I left it. That point is about 1/2 turn from where I had the 950 idle. It is very repeatable. idle is about 700, timing is still 12 advanced with vac. Vac off drops to the R16 setting of 0tdc.

One more: I found a post on adjusting the mix on a 91 560, that discribed a button and LED on a diagnostic connector back by the battery. Mine doesn't act that way. With the ignition on and engine off, led is lit, pushing it does nothing. With engine running led is off but pushin button turns it on only as long as button is pushed.

What next.