Mercedes-Benz Forum banner
Cancel
Create thread New Garage Forums

California smog...!&*@

Jump to Latest
41 - 60 of 100 Posts
#41 ·
nzvlnr said:
When the Indie shop put a timing light on it they said if it was 31degrees advanced it would be running this good. He said it appears to be 20 degrees advanced, which would point to the resistor as it is supposed to advance the timing 6 degrees when it is potentially bad. They are a good shop and he really knows these cars.
Click to expand...
The perceived and actual timing are the issue, no engine will run and pull smoothly with a 20-31°BTDC setting at idle. Those settings are usually at >3,000RPM, i.e. when the distributor's weights are at maximum extension, providing maximum advance. Remove a plug on No. 1, get the piston to the top on the firing stroke, then check where your timing marks sit on the pulley relative to the pointer.
 
Save
Reply Quote Like Like
#42 ·
Ralf_CT said:
If your current idle setting is 31°BTDC, it will be even higher under revs, it should be pinging like crazy and be undriveable. How does it run, if it runs okay then the actual timing is fine and something else is amiss? When our local octane changed from 98 to 95 I had to reduce my previous W123's timing from 10° to 6° to eliminate the pinging, it no longer idled so nicely and lost some power, but that was okay.
Click to expand...
...that's what I had in mind when I wrote: "About 30° or more off timing is just not possible and can't be produced by any vacuum issue "
With this timing the engine would run the other way.
Sure that they clamped the timing light to the right wire? There are 9 possibilities.
:)
And by the way: You can start experiments with all possible resistor configurations but this won't help. I'm pretty sure that the timing is perfect, just the dislayed situation is wrong
All what the igniton system needs is a signal from the crank sensor and power to the ICU, even without vacuum it would do its job.

Cheers Martin

Image
 
#43 ·
ill give my 2 cents, im not familar with your particular car but electronic ignition controlled by the ECM is pretty much the same across the board. The balancer could certainly have spun a bit giving a false reading, Ive seen it a few times. The erratic timing light could be causing a bad reading, its probably a dial back to zero style maybe they dont have it set correctly to start with. The light should be pretty steady if its jumping all over id check all the wiring from the crank sensor, clean all the connections. Make sure cap, rotor, wires are all good. Loose timing chains can cause erratic timing as well. If it runs well i concur that it cant be 30degrees advanced at idle. It would be really hard to start and wouldnt run well at all.
As a cheat you could bend the pointer till it was at the spot they want it.....heck it passes the tailpipe test...
 
#44 ·
Martin_fromGermany said:
...that's what I had in mind when I wrote: "About 30° or more off timing is just not possible and can't be produced by any vacuum issue "
With this timing the engine would run the other way.
Sure that they clamped the timing light to the right wire? There are 9 possibilities.
:)
And by the way: You can start experiments with all possible resistor configurations but this won't help. I'm pretty sure that the timing is perfect, just the dislayed situation is wrong
All what the igniton system needs is a signal from the crank sensor and power to the ICU, even without vacuum it would do its job.

Cheers Martin

View attachment 2763518
Click to expand...
But the Indie guy knows these cars. ;)
 
Save
Reply Quote Like Like
#45 ·
THEDAD said:
The erratic timing light could be causing a bad reading, its probably a dial back to zero style maybe they don't have it set correctly to start with.
Click to expand...
Excellent point!
 
Save
Reply Quote Like Like
Discussion starter · #46 · (Edited)
So we are all on the same page. I appreciate the input. But to clear things up:

1) The young kid at the smog shop who failed me said it was 31 degrees out of time, not the indie shop. I protested and said the car would be running like crap, as we were looking at the car. It passed all of the other smog tests.
I have never had a car fail because of timing so I questioned his procedure..."no vacuum line to pull or plug to get the correct reading?" He showed me the book of the procedure to test the timing. I had already been there (when they opened) for two hours at this point. I knew something was not right and the car runs great.

2) The indie shop owner had one of his mechanics throw a test light and try to adjust the distributor timing admitting we cannot adjust the timing on this car on the distributor. We did see the timing jump around. This was a bring it in and we will check it real quick, no charge. He said it is either the harmonic balancer rubber has deteriorated and is showing a wrong timing condition and the timing is fine. He did not think it was the ezl control unit because it would be running terrible if it was.
They measured the timing it to be about 20 degrees advanced.

3) The car has been tuned up and has been running GREAT! There is about 900 miles on the new cap, rotor, plugs ,plug wires, fuel pump+ filter, fuel injectors+ injector seals on the car. The car passed smog 2 years ago no problem, they did not check the timing...

4) They set the timing light up, from the start. My timing light read about the same what they stated about 12 degrees BTDC is the factory setting and my timing is at 20 degrees ( at least that what it reads)

Could I have a bad crank sensor to some degree? In the past if a crank sensor was bad the car would not start and would not run well.

86k original miles on the car. I bout it from a 94 year old neighbor
 
#47 ·
Bad crank sensor wouldnt change timing and like you have witnessed the car wont run. They pretty much work or dont. Had another thought, might check and see if one of the inputs such as an intake temp sensor is malfunctioning, some vehicles will advance the timing some when below a certain temp. Im not sure on the 560. But its a possiblity and shouldnt be hard to check.
 
Discussion starter · #48 ·
Ok....Progress made??
I pulled the ignition resistor , hooked up my timing light started the car and let it run. The timing is now below the 0 ( retarded the timing) . I think it will now pass smog? The resistor must be caput!?

Another problem - I think I hear pinging from the motor. I read another thread that says if you do this and dont use high enough octane it will ping. I always run super in her...91 octane rating.
 
#49 ·
91 should be fine for this, if you hear detonation “pinging” the timing is definitely too far advanced. I would certainly check 0 degrees top dead center with the balancer to confirm nothing has changed on the balancer reading.
 
#50 ·
nzvlnr said:
Ok....Progress made??
I pulled the ignition resistor , hooked up my timing light started the car and let it run. The timing is now below the 0 ( retarded the timing) . I think it will now pass smog? The resistor must be caput!?

Another problem - I think I hear pinging from the motor. I read another thread that says if you do this and dont use high enough octane it will ping. I always run super in her...91 octane rating.
Click to expand...
The real problem is this state we live in. I am so happy my ‘74 is exempt from this BS.
 
#52 ·
nzvlnr said:
Ok....Progress made??
I pulled the ignition resistor , hooked up my timing light started the car and let it run. The timing is now below the 0 ( retarded the timing) . I think it will now pass smog? The resistor must be caput!?

Another problem - I think I hear pinging from the motor. I read another thread that says if you do this and dont use high enough octane it will ping. I always run super in her...91 octane rating.
Click to expand...
Great - and very interesting.

You removed the resistor and noticed a 20° change in ignition timing?
So when you put the resistor back in, the ignition timing is again advanced by 20°?

On a normal 560SL removing of the resistor causes an advancing from about 6° and not a retarding.

Cheers Martin
 
Discussion starter · #54 ·
Martin_fromGermany said:
Great - and very interesting.

You removed the resistor and noticed a 20° change in ignition timing?
So when you put the resistor back in, the ignition timing is again advanced by 20°?

On a normal 560SL removing of the resistor causes an advancing from about 6° and not a retarding.

Cheers Martin
Click to expand...
pulling the resistor retarded the timing bringing it below the 0, look at post # 5, I took a snapshot of the timing before I pulled the resistor or do I have it backwards and this advanced the timing as it now reads a tad lower in reference to 0?
 
#57 ·
nzvlnr said:
Here is a picture of my timing now, after the resistor was removed. I let the car warm up then took a snapshot. I think it is within spec now??
Click to expand...
Hi, that's looking good, but up to now I didn't understood the behavior.
Since pulling the resistor advances the timing, I cannot understand the correlationships mentioned in this thread. Of course, this may be a problem with my limited English skills but from a technical point of view I cannot understand, how the timing can advance that far without noticeable change in idle quality and/or acoustic behavior.
For that I asked, if the timing really switches back if you put the resistor back in place (during one timing light session).

Cheers Martin
 
#58 ·
It looks like pulling the resistor gave the expected result, the timing advanced by about 6 degrees from where it was. The intial reading was about 6 to 10 degrees advanced from spec. This system uses a temperature sensor as one of the inputs to determine the timing setting. Perhaps this sensor is not working correctly or the connection is bad, throwing the timing off. Perhaps there is a problem with the control unit or the vacuum connection. Every input needs to be checked and eliminated one by one.
 
Discussion starter · #59 ·
Martin_fromGermany said:
Hi, that's looking good, but up to now I didn't understood the behavior.
Since pulling the resistor advances the timing, I cannot understand the correlationships mentioned in this thread. Of course, this may be a problem with my limited English skills but from a technical point of view I cannot understand, how the timing can advance that far without noticeable change in idle quality and/or acoustic behavior.
For that I asked, if the timing really switches back if you put the resistor back in place (during one timing light session).

Cheers Martin
Click to expand...
So you say it looks good and AlterShinken says it advanced more?? If the timing moves to the right this is retaded, if it goes to the left ( which it did not) it is advanced or am i wrong, would not be the first time....!!
 
Discussion starter · #60 · (Edited)
AlterSchinken said:
It looks like pulling the resistor gave the expected result, the timing advanced by about 6 degrees from where it was. The intial reading was about 6 to 10 degrees advanced from spec. This system uses a temperature sensor as one of the inputs to determine the timing setting. Perhaps this sensor is not working correctly or the connection is bad, throwing the timing off. Perhaps there is a problem with the control unit or the vacuum connection. Every input needs to be checked and eliminated one by one.
Click to expand...
The timing reading went to the right, this is retarded, if the mark moved more to the left it would of advanced more?
martin_fromgermany says it is in spec?
 
41 - 60 of 100 Posts
About this Discussion
99 Replies
22 Participants
Last post:
Martin_fromGermany
Mercedes-Benz Forum
posts
7.8M
members
748K
Since
1999
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!
Full Forum Listing
Explore Our Forums
W126 S,SE,SEC,SEL,SD,SDL Class R/C107 SL/SLC Class W163 M-Class W124 E,CE,D,TD Class W210 E-Class