HOLY SMOKE !!! - Mercedes-Benz Forum
 
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post #1 of 9 (permalink) Old 10-13-2014, 07:32 PM Thread Starter
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HOLY SMOKE !!!

Yes, HOLY smoke, as in the kind of smoke produced by a can of Sea Foam.

As my saga continues with my 1980 450SL, I decided to run a compression test tomorrow. Before I ran that, I wanted to do a last-ditch cleaning effort.

So, I went to Harbor Freight to pickup the compression gauge ($30), and as my car was now at operating temp, I poured an entire can of sea foam down the throat (slowly) while keeping the engine around 2000 to 3000 rpm, then the last few ounces all at once nearly (but not quite) killing the engine.

I shut the engine off, and walked over to get a tasty In-N-Out burger. (I had parked near an In-N-Out because it takes a LONG time for ten to take your order and server you the burger, so this would be a good way to kill time while the Sea Foam settled in).

Indeed, about 27 minutes later, I was finishing my yummy 3x3 burger (three patties, three slices of cheese), and hopped into Freya and started her up.


BIG PLUMES OF HOLY WHITE SMOKE!!!

I got on the freeway as quickly as possible, and did the "spirited drive" (as much as possible in LA traffic).


And now - NOW - the car is PRACTICALLY PURRING LIKE A KITTEN.,


Nevertheless, the saga is far from over.


DUTY CYCLE


Hooking up a digital duty cycle gauge I found that, regardless of where I adjusted the mixture control on the fuel distributor, the DUTY CYCLE remained at 59.7%.

In reading lately, I see that a duty cycle of 60% is "limp home mode" due to a failed O2 sensor.

SERIOUSLY?


A few months ago I paid $700 for a "tune up" (including belts, spark plugs ect) but it looks like it mostly needs an $20 O2 sensor??

If all this drama is really about a failed $20 part, I am about to go through the ROOF.

After a Sea Foam and freeway rive, the car is running much smoother (idle a bit too high now), so tomorrow I plan on checking the compression (maybe tonight) and working rom there. But I have hope that the compression may check out, and I only need to fix an O2 sensor and perhaps some vacuum leaks or other minor parts.


STAY TUNED FOR MORE OF THIS SAGA.... !





EDIT (Nov 26): Oh no it wasn't - the car problems were far deeper and more systemic that an O2 sensor. See my MAIN THREAD

Last edited by Myndex; 11-26-2014 at 08:58 PM. Reason: CUz I didn't know then what I do know now, LOL
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post #2 of 9 (permalink) Old 10-13-2014, 07:37 PM
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Aint seafoam a hoot!
Glad you are making headway to a resolution. Perhaps the ole aluminum heads are fine...

Best Regards...

RM Smith
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Where is it again that we are going... And why are we in a handbasket?
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post #3 of 9 (permalink) Old 10-13-2014, 09:31 PM
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Never considered O2 sensors as part of a tune-up. More of a change if/when needed item.
ps...don't you love In n Out Burgers!!!!
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post #4 of 9 (permalink) Old 10-13-2014, 10:10 PM Thread Starter
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Quote:
Originally Posted by Ears View Post
Aint seafoam a hoot!
Glad you are making headway to a resolution. Perhaps the ole aluminum heads are fine...
My fingers are crossed - I have a helper tomorrow to turnover while I look at the meter I just bought. Will report results... here's hoping!


Quote:
Originally Posted by reno4u2 View Post
Never considered O2 sensors as part of a tune-up. More of a change if/when needed item.
ps...don't you love In n Out Burgers!!!!
Yea, do I add the 3x3 and large coke to my total repair cost?

Yea, I guess the o2 is not part of a tune up, but I did emphasize that I wanted the ar to pass smog, and $700 later I have new belts that squeal on acceleration, and a car that fails smog, possibly due to a bad o2 sensor.

I am just plain annoyed at the moment. ever read "Zen and the Art of Motorcycle Maintenance"? It seems very apropos here.

Last edited by Myndex; 10-13-2014 at 10:13 PM.
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post #5 of 9 (permalink) Old 10-13-2014, 10:36 PM Thread Starter
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OKAY new info - warm restart results in stumble until driven for several blocks. My assumption is FUEL ACCUMULATOR. Also, idle speed is inconsistent - I'm thinking the WUR is partly to blame (previous testing shows the heater coil is open).


My current plan (in order of priority and action):

A) Full compression test - if it passes then:

B) Ultrasonic clean all injectors.

C) TEST/Evaluate
  • Cold Start Injector. I have reason to believe it is leaking.
  • Idle Aux Air Valve. I don't know if it is stuck or operating.


D) Definitely Replace:
  • O2 sensor
  • Fuel Filter
  • Fuel Accumulator
  • all injector seals and O rings
  • Distributor cap & rotor
  • Cracked ignition resistor

E) Recondition/Rebuild:
  • Warm Up Regulator. I know the heating element is open, and so I believe this is partly the problem of low idle when the car overheats.
  • Idle Aux Air Valve.
  • Flush cooling with Dawn, then acid flush, then fresh coolant.
  • *Maybe* have radiator rodded out.


F) Possibly Replace:
  • #1 and #5 injectors (if can't be cleaned/restored)
  • Ignition Coil (unsure if necessary to replace)
  • Cold Start Injector. (Possibly bypass for now due to high cost if it is leaking.)
  • EGR Valve
  • Air Pump Bypass Valve

--------

B thru F are only IF it passes compression - so maybe I'm putting the cart before the horse, but I am hopeful that compression is serviceable.
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post #6 of 9 (permalink) Old 10-14-2014, 12:02 AM Thread Starter
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In searching the web, I found this as a great cheat sheet on the Lambda system and mixture adjustment.

BOSCH KE3-JETRONIC MIXTURE ADJUSTMENT

While this seems to detail the 88-91 KE system, it seems very much the same as the 1980 system.

----------------------------
EDIT (Nov 26): oh no it isn't ! There are important differences between KE and K, among other things you CAN NOT use a standard duty cycle meter without modifying the ECU.
----------------------------

Most especially, the PINOUT of the 9 pin X11 connector, which I'll quote here (because I can not find this important info ANYwhere else):


Pin (updated Nov. 26 to correctly reflect the 1980 thru 1985 versions of this vehucle).

1 RPM signal, 0 to 12 V, 4 pulses per revolution. A frequency of 43.3 pulses per second corresponds to the desired idle speed of 650 RPM. (To check your tachometer you could measure the frequency at this pin and multiply by 15 to get RPM.) This signal is derived from the ignition amplifier and is synchronized with the low side of the ignition coil.

2 GROUND

3 Frequency Valve signal. This is a tap of the signal that drives the frequency valve. This signal can NOT be read with a duty cycle meter. You need either the Bosch tool, OR an oscilloscope to read the signal on pin 3.

4 Low (negative) side of the ignition coil. This is where to monitor the dwell angle of the electronic ignition amplifier, and is also a good place to view a reflected and attenuated image of the spark. This is about 50 VPP, safe for an ordinary oscilloscope.

5 Hot (battery voltage) in Run or Start, NOT FUSED! This is actually the positive side of the ignition coil.

6 Hot at all times, through fuse 2

7 Shielded cable from TDC sensor. This is not the same sensor which triggers the spark control unit, but it could be used in a clever circuit with pin 1 to measure spark advance.

8 Shielded cable from TDC sensor.

9 Shield for pins 7 and 8.


EDIT: (Nov 26th) Do NOT use KE-Jet info for tuning a K-Jet with Lambda system. See THIS THREAD instead.

Last edited by Myndex; 11-27-2014 at 01:41 PM. Reason: Update to prevent misleading info.
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post #7 of 9 (permalink) Old 10-14-2014, 01:57 AM
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I was just in LA. I did the 1 route down the coast. I saw 14 107s, nearly 2 a day. Impressive!

I also saw a sorry 107 in Sausalito. It had been painted blue, with ships, sails boats, etc. I mean... like I would paint it: hardly better than a 5 year old. Maybe a parts car.

But I don't remember a smoking 107, so I missed your show just by a few days :-DD

107's wiki:
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Looking for original backseats + their hardware.
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post #8 of 9 (permalink) Old 10-14-2014, 03:30 AM
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Quote:
Originally Posted by bereng View Post
I also saw a sorry 107 in Sausalito. It had been painted blue, with ships, sails boats, etc. I mean... like I would paint it: hardly better than a 5 year old. Maybe a parts car.
That car was on Craigslist for a while, and may still be. High miles, but supposedly runs and drives. I had thought about rescuing it (the sale price was very cheap), but in the end getting it to Minnesota proved prohibitive.
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post #9 of 9 (permalink) Old 05-21-2019, 01:32 AM
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Quote:
Originally Posted by Myndex View Post
In searching the web, I found this as a great cheat sheet on the Lambda system and mixture adjustment.

BOSCH KE3-JETRONIC MIXTURE ADJUSTMENT

While this seems to detail the 88-91 KE system, it seems very much the same as the 1980 system.

----------------------------
EDIT (Nov 26): oh no it isn't ! There are important differences between KE and K, among other things you CAN NOT use a standard duty cycle meter without modifying the ECU.
----------------------------

Most especially, the PINOUT of the 9 pin X11 connector, which I'll quote here (because I can not find this important info ANYwhere else):


Pin (updated Nov. 26 to correctly reflect the 1980 thru 1985 versions of this vehucle).

1 RPM signal, 0 to 12 V, 4 pulses per revolution. A frequency of 43.3 pulses per second corresponds to the desired idle speed of 650 RPM. (To check your tachometer you could measure the frequency at this pin and multiply by 15 to get RPM.) This signal is derived from the ignition amplifier and is synchronized with the low side of the ignition coil.

2 GROUND

3 Frequency Valve signal. This is a tap of the signal that drives the frequency valve. This signal can NOT be read with a duty cycle meter. You need either the Bosch tool, OR an oscilloscope to read the signal on pin 3.

4 Low (negative) side of the ignition coil. This is where to monitor the dwell angle of the electronic ignition amplifier, and is also a good place to view a reflected and attenuated image of the spark. This is about 50 VPP, safe for an ordinary oscilloscope.

5 Hot (battery voltage) in Run or Start, NOT FUSED! This is actually the positive side of the ignition coil.

6 Hot at all times, through fuse 2

7 Shielded cable from TDC sensor. This is not the same sensor which triggers the spark control unit, but it could be used in a clever circuit with pin 1 to measure spark advance.

8 Shielded cable from TDC sensor.

9 Shield for pins 7 and 8.


EDIT: (Nov 26th) Do NOT use KE-Jet info for tuning a K-Jet with Lambda system. See THIS THREAD instead.
Thanks for some fantastic threads and useful info. Where on the car can i find this connector?
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