Hello guys! I'm back, but using a different name since I forgot my login information.
We had issues with the distributor and put a rebuilt one on. The actual problem turned out to be a rusted fuel tank that we had sent off and fixed. A local mercedes place did all this work for us. They still can't get it to run well. So we have it back home now.
So here's the current concern. I took out and cleaned all Fuel Injectors and they seem to all spray well. So then just to check, i took the injector lines off the distributor to do a test with the metering plate to see that fuel is coming up and even. When I turn on the ignition (without cranking) the Cold Crank sensor pumps a bit of fuel in and all the holes in the top of the distributor fill up evenly. But, when I press the metering plate down, I hear a "click" and nothing happens. Shouldn't it start pumping fuel up and out of the holes??
Thanks and I expect to be on here a lot for the next while getting this car running again..
Thanks and sorry I forgot that part. It's a 1988 560SL. and "We" is my family as we've been working on this car, but they just gave me the car as a graduation present so now it "I" and "Me"!
When the car does turn on and barely stay running, it is smoking out of the tailpipe. Its not white like oil or black like gas, it seems to be grayish and smells badly of fuel. If i stamp down on the gas, it will not get over 3k RPM. This made me think fuel starvation which is why I did the plunger test.
So, isnt the plunger with ignition "on" supposed to send fuel up the distributor ports with injector lines off??
... When I turn on the ignition (without cranking) the Cold Crank sensor pumps a bit of fuel in and all the holes in the top of the distributor fill up evenly. But, when I press the metering plate down, I hear a "click" and nothing happens. Shouldn't it start pumping fuel up and out of the holes??
Thanks and I expect to be on here a lot for the next while getting this car running again..
I’ve never heard of a “Cold Crank sensor”, let alone of one that can pump fuel. ... What is that? :wink_2:
Anyway, the observation you describe sounds okay. ... The fuel pump(s) only prime for about one second when the key is turned to “ignition on”. After that the fuel pressure drops by roughly 50% and the pressure regulator closes. That “holding pressure” is then the same in the whole fuel distributor. And with the same pressure in the lower chambers of the differential pressure valves as in their upper chambers no fuel is supposed to come out of the injector pipe ports, no matter how far the air flow sensor plate is pushed down.
Woops, I combined my Land Rover crank position sensor that I'm currently having troubles with, with my cold start valve on the 560sl..
It may have been the wine last night that did that one..
So anyways, if I turn the ignition to the "on" position and fuel comes into the chambers/fuel injector ports, that is a good sign for the cold start valve? I'm trying to do a process of elemination of the problems possible. Or is it the fuel pumps that push that orginal bit of fuel in when the ignition is turned.
SO, when I press the metering plate down, I thought fuel should start coming up from the distributor chambers.
... if I turn the ignition to the "on" position and fuel comes into the chambers/fuel injector ports, that is a good sign for the cold start valve? I'm trying to do a process of elemination of the problems possible. ...
No … not if the fuel pumps are not running. They run only for about a second when the key is turned to “ignition on”. They are switched on again when the key is turned further to “cranking”, respectively they stay on if the key is turned quickly enough further to “cranking”.
In a little more detail:
When the fuel pumps start to run the “system pressure” is generated via fuel pressure regulator. When they stop running, the fuel pressure regulator closes again and the fuel pressure drops back to the “holding pressure”. See what I said about the “holding pressure” in my last post.
If, for instance, you would pull out the fuel pump relay and bridge the relay’s socket with a wire in order to let the fuel pumps run continuously (no matter whether ignition is switched “on” or “off”), you would observe what you expected to observe.
Only when the fuel pumps are running (“system pressure” generated) and the control plunger has left its rest position due to the pushed down air flow sensor plate, the lower chamber pressure is a little lower than the upper chamber pressure. That opens the differential pressure valves, due to their valve plates moving to a lower position, away from the injector pipe port’s inlet opening in the upper chambers, so that fuel can flow to the injectors.
OK so I pulled and replaced all the spark plugs and check the firing order and found that the passenger side was all wrong!.. I fixed that and the car started up great! I could Rev it up to 5,000+ rpms without problem it still idled rough though... After a few minutes it started running rough again and now it completely bogs out when I touch the gas pedal. I drove it around the neghborhood and it rides fine, as long as im not on the gas.. I can here a muffled backfire from the engine..
Is this a fuel distributor problem? or could it be vacuum leak or timing issue??
On the bright side, I can actually drive it and it idles pretty good now! just can touch the gas..
I would recheck your firing order. Was there a big backfire when the muffler blew off.
You need to get a CIS pressure gauge to start with and get some real facts. I concur with others that you will need to jump the fuel pump to do the kind of test you are trying but I would think the accumulator should hold enough volume at pressure to at least get the ports to over flow.
Hey Chris great looking SL and love the colour. There's going to be lots of little things to rectify(like your muffler) but once you have 90% of this stuff fixed the joy of owning and driving your 107 will be priceless.
Good thing I'm skilled and enjoy fixing cars... My old Porsche 914, the CJ-7 and my current Discovery2 have kept me busy over the years.. So I just laughed at the muffler, that should be an easy fix..
Here is a video of the current condition.. To get it to start I have to pump the pedal.. Once started, it idles ok.. Even the slightest tap of the throttle and it wants to stall out.. I can sometime feather foot it up to 3k rpms as this video shows, but it wants to stall..
The economy guage is pegged left at idle, so I assume no vacuum leak..
So I just cranked the SL this morning in 26 degree weather.. It started up and ran like a champ! I went flying up the road, and as soon as the engine began to warm up, it went right back to crap... Barely idles and any gas chokes it out..
I unplugged the EHA valve on the side of the distributor and nothing changed..
So if the distributor was bad, wouldnt it always run bad??
What else could cause it to run like crap as soon as warms up??
It also smokes like hell when I cranked it up... but then the smoke goes away
In my last post I wrote: “Assuming that you've checked ignition components (cap, rotor, wires, spark plugs, timing …) …”
Have you checked these things ?
That makes the CTS (coolant temperature sensor), respectively input about the engine's temperature to the ECU, or any other sensor and its input to the ECU with effect on the EHA less of a suspect.
Also check your O2 sensor. Before reaching operating temp the ECU will give a 50/50 signal to the frequency valve. When in operating temp, the O2 sensor takes over and signals the ECU. If it is shot it may give a wrong signal and the ECU tries to over compensate (either too rich or too lean). You can easily check with a multimeter on the X11 diagnostic port. Here's a good write-up: BOSCH KE3-JETRONIC MIXTURE ADJUSTMENT
It's a fairly easy check and if the O2 sensor is original it is probably time to change it. Bosch aftermarket is not expensive.
So I guess my suggestion on checking the O2 sensor and closed loop operation was a bad one. Sorry. Not sure how obvious the widespread misconception between Landiss and H.D's duty cycle adjustment lies, but anyway that's probably not relevant to the OP's issue with a very rough running engine. So lets move on.
No, not a bad suggestion at all … it's just not necessary to check the o2 sensor at this point, due to the OP’s statement that unplugging the EHA did not change anything. I almost overlooked it myself … I even went back and edited my own post 22 later last night when suddenly it came to me that I forgot about that statement towards the end of that post. :wink_2:
... Not sure how obvious the widespread misconception between Landiss and H.D's duty cycle adjustment lies, but anyway that's probably not relevant to the OP's issue with a very rough running engine. ...
That misconception is not very relevant for the OP’ issue … not at this point. … But some hints in my version, which are not addressed at all in Landiss’s version, are IMHO relevant for any duty cycle check / adjustment.
So instead of fooling with the delicate airflow meter, should I just replce the O2 sensors and see what happens?? Or is it not the O2 sensors if the EHA unplugged didn't change anything??
The unplugged EHA not changing anything indicates that it’s not an o2 sensor problem … unless there’s also a problem with the EHA or ECU, or a Lambda adjustment beyond the EHA’s Lambda leaning or enriching limit. ... I explaned that in detail in the link I mentioned in post 15.
Did you check the other things I mentioned in that post ?
- ignition components (cap, rotor, wires, spark plugs, timing …)
- smoothness of the air flow sensor plate’s / control plunger’s movement
If these things are okay, I’d suggest to check the rest of the things I mentioned in that post !
- first the Lambda control (duty cycle) adjustment
- then the fuel pressure ("system pressure" and "lower chamber pressure")
Your right about not carelessly fooling with the Lambda control (duty cycle) adjustment screw … but checking the adjustment is practically risk-free.
The voltage while the engine is not really at operating temperature is irrelevant.
Besides voltage Vp3 (between port 3 & 2 of X11) also voltage Vp6 (between port 6 & 2 of X11) should be checked at 'ignition on' and at idle and at (about) 2500 rpm.
Vp3 behavior like the one you report so far represents a duty cycle jumping to excessively low values, which represents an air/fuel mixture jumping to ‘rich’. That can for instance be caused by a leaky CSV (cold start valve). Also worn injectors could be the reason … but you said you checked them and they sprayed well (homogeneously), right?
Please don’t forget to answer my questions in posts 15 and 24:
What exactly do you mean by “a rebuilt FD has been installed”? Was the FD taken apart and reassembled with new parts in it?
Did you check the ignition components (cap, rotor, wires, spark plugs, timing …)?
Did you check the smoothness of the air flow sensor plate’s / control plunger’s movement?
I ran the engine in those videos for about 20mins.. I can't seem to get it to warm up over 80 degrees for some reason... I will try to drive it to see if I can get the temp higher..
Were you able to address your rusty gas tank problem? If there is rust canker in your tank real bad you may have to search for another tank. I noticed that eBay had some decent clean tank for sale over the past few months. Be selective. I had to clean my tank of the rust and gas varnish. Below is a couple of before and after shots. The last shot is your swirl pot in action (the photo loaded side ways for some reason). I used an iPhone with the camera lens on the corner of the phone. I stuck the camera corner in the gas tank sending unit hole to get these shots.
I used 2 gallons of molasses to remove the rust in my tank. See Amazon link below. Plug off all the holes on the tank. Pour 2 gallons of molasses in the tank fill it part way with water. Slosh it around to get the molasses well diluted. Tip the tank up so that the filler neck is straight up. Then fill the tank till full. You want to make sure all the air is out of the main part of the tank so the molasses solution is touching all of the metal interior. Let it sit for 2 weeks or more. After the two weeks (or more) is up dump out the molasses and flush thoroughly with water. I poured out the molasses on my lawn on a brown spot.
I've also done a video with the volt meter using the #6 and #2 pin...
This is the very first cold start of the day... The economy peg never moves and it responds well to the gas pedal as i rev it up and down...
This next video is near operating temperature. The economy peg moves far right, and I can barely get the RPMs up over 2,000... you can hear the bogging out..
As for answering the questions about the wires, cap, plugs and that stuff... All have been replaced and or checked as we've been working on this. The plug wires and plugs are new. The cap is clean and clear. the Injectors were all cleaned together and have a good spray patter.
Make sure the thermostat is working well. It should not take 20 minutes to get to 80°C.
You say you replaced / checked the ignition components. Did you also check their resistances when the engine is warm ?
On your car they should be:
- coil’s primary winding (between terminal 15 & 1): 0.2 - 0.4 Ω
- coil’s secondary winding (between terminal 4 & 1): 8 – 13 kΩ
- wire between coil and distributor: < 1 Ω
- distributor rotor (between its two terminals): about 1 kΩ
- each distributor cap pole (except center pole): about 1 kΩ
- wire between distributor and spark plug connector: < 1 Ω
- spark plug connector: about 1 kΩ
- spark plug type: non-restistor
Make sure that the wires are properly connected (coil / distributor cap / spark plug connectors) and that the spark plug connectors are properly fixed to the spark plugs.
If you measure the resistance between each pole inside the distributor cap and the respective spark plug connector, the resistance should be about 2 kΩ.
In order to check if the CSV is leaky, pull it out far enough to see if fuel comes out, but leave the fuel pipe connected to it. Then pull the FPR (fuel pump relay) out of its socket and bridge the socket terminals 30 & 87 with a short wire, so that the fuel pumps run. Then check if fuel is dripping or even spraying out of the CSV. I suggest to do that test when the engine is warm.
There are two questions in my last post you haven’t answered yet:
Was the FD taken apart and reassembled with new parts in it ?
Did you check the smoothness of the air flow sensor plate’s / control plunger’s movement ?
And I add another question:
Did you check the air flow sensor plate’s zero position ?
All wires are nearly new and resistance is good with them. Cap is good as well..... If if was wires or an ignition problem wouldn't the engine run like crap the whole time??
I pulled the CSV and jumpered the pumps.. nothing leaked at all...
again.. it only runs bad once it warms up.. otherwise it starts great and idles and revs great! then as soon as it heats up, it falls apart..
Not necessarily … heat can cause problems with ignition components, for instance with the coil or the distributor (cap and rotor).
Your car, I assume, is equipped with a 2-terminal CTS (coolant temperature sensor). Terminal 2 should be connected to the CIS-ECU and terminal 1 to the EZL (ignition control unit). I said earlier that the fact that the test drive with the EHA unplugged showed no change at all, “makes the CTS less of a suspect”. But since, due to its input to the EZL, it is still a possible suspect, I suggest to check its resistance between each of its two terminals and engine ground at a coolant temperature of 80°C (should be in the range of 290 – 360 Ω).
There’s still one unanswered question left: Has the FD been taken apart and reassembled with new parts in it ?
The air flow metering plate pushes down smoothly and comes back up smoothly.. the slows near the end and stops where it should..
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