1988 190E 2.3 stalling
 

It occasionally stalls when I come to a complete stop. After replacing the stuff that I listed below now it has a hard time starting where it sputters at low idle then dies unless I keep pressing the accelerator and catch it on time.
Replaced parts:
O2 sensor
Fuel pump
fuel filter
Fuel pump relay
OVP
ICV
ICV hoses (lower and upper)
Fuel pressure regulator
Coolant sensor
air filter
spark plugs
ignition wires
Distributor + cap (ignition)
Complete new exhaust from header down including new cat converter.

Action taken:
Adjusted ignition timing by setting the front balancer where the T mark is exactly on the pin located on the block and the distributor centered on the notch. The strobe light indicated no drift with zero degrees set on the gun while the car is at idle. Beyond that I am clueless if I need to make other adjustments and how.
Tested fuel pressure at the distributor and then tested the fuel pressure differential between the upper and lower chamber (see results below) then I tested the Lambda duty cycle at Pin 3 while at idle (see results below).


Test results:
Fuel pressure 5.5
Fuel differential .4
Duty cycle 50%

Please, reply only if you know what you're talking about:mad: Pictures will help as I have severe ADD:eek:

Crank position sensor is a common issue for a slowing to a stop/idle stall. If it even briefly doesn't get a good signal from it then it shuts down the fuel system. Happened on our 300E until I replaced it.

I think I tested for that one but I don't recall the details other that I didn't see anything out off specs. I will check my notes.

I checked out that part at ******** (description and price)
but I have a feeling that it's not the right one.

Picture from link
[IMG]http://www.***************/secure/PartImages/0021531328.jpg[/IMG]

Can you confirm?

Thats not it, thats the "tachometer pickup". The crank position sensor is at the back of the engine. It costs about 2x as much and looks like this:

http://img.eautopartscatalog.com/hir...300&height=300

Mine still tested within spec too.....but the new one "Tested better" within spec.....and I haven't had it stall since I replaced it. (months ago)

That's what I thought, thanks!

What are the probabilities for one of those to go bad? It has no moving part and I believe it uses a Hall effect to signal to the EZL, is that correct?

Not sure on that, but it seems they do go bad when they are older. Not so much from "wear" as the degradation of the wire and connections. After 20 years they seem to just fall apart.

Ok, here is an update: I figured out why the car was not starting properly and that was the OVP being loose from the its harness. The car started right up after I took care of that issue but that didn't solve the stalling issue at a stop.
I went ahead this morning and swapped in a crank position sensor that I pulled from another car just to see if that would make a difference; nope! I am still having the same issue where the car stalls at a stop.
The stalling comes in different flavors where sometimes the rpm surges a bit, sometimes it simply drops to 500 or the rpm start fluctuating up and down with the oil pressure doing the same; all these observations are right before the car stalls, it all depends what the car feels like throwing at me.
I did hear some sort of relay clicking in one of my stalling sagas. It sounded like it was on my left side near the speaker. As soon as I heard it click the car went dead.

Is the duty cycle fixed at 50%? Can you rig the car so as to read the duty on the road? No intake leaks? Just thinkin'.

My air/fuel mixture tower is still intact with the sealed ball and I intended on keeping it that way as much as possible. The 50% duty cycle I got was at idle; I forgot to measure at other rpms:o But remember my O2 is brand new.
I can rig the car where I can read the current to the EHA and the voltage from pin 3 on the test pod but the car does not have any issues while moving (as far as I can tell).
The current on the EHA when the car is warm and idling fluctuates between +1mA and -1mA. Does that help?

As to intake leaks, believe me, I went through this think in every way. The only leak I have is at the control valve for the heater unit inside the dash. That one is so small that I wouldn't think it would have such a dramatic effect as to stall the car.

The fixed 50% reading indicates no o2 sensor function. I would test the o2 sensor with a volt meter. I would also lose the ball in that mixture tower. The on/off ratio is a starting point for all other diagnosis from what my feeble mind recollects. A fluctuating 50% may be ok tho.

Ok, it wasn't a steady 50% so yes you're right, if it was steady then the O2 could be fubar but that's not the case here.

Hummmmm....
 

Hi,

Look like a cold solder in the electronic component behind the battery.

Your duty-cycle is perfect, your EHA too at -1 to +1 mA

Take a hammer :D and gently thumble all the electronic component behind the battery at idle, engine at 80C°. You may hit the one who make the car stall.

Max

PS. Don't use a 4 pounds hammer :eek:

I would be betting on the air flow potentiometer being worn out.

all those systems go lean over time and the ball needs to be taken out and move the 3mm fuel adjustment clockwise 1/8th turn.this will be very close.

But the EHA shows nominal reading and the lambda is just fine, why would I mess with the fuel/air mixture? Do you maybe think that it's internal, which means even if balanced on the outside the engine will stall as if a richer mixture is the cure?

I have an extra one of these but the existing one showed linear reading without interruption when I moved the air plate and used an Ohmmeter to read the change in resistance. They both did the same thing. (I also have an extra fuel distributor:) )

Ok, I just swapped the crank sensor from a working car where I also put my old in the other car. The other car didn't stall but the one in question did. In conclusion the crank sensor didn't resolve this stalling issue.
What's next?

You don't say you cleaned the idle control valve - that can get sticky around idle position and not respond quickly enough to avoid a stall. Removing it and soaking in alcohol usually works well. Best to pre-purchase the rubber holder and hoses since they harden to fragility over time. Also clean the airflow meter flap and throat to prevent sticking.

Steve

The ICV and its hoses are all new. the airflow meter flap is clean and moves nicely.

Next, then... There is are microswitches on the throttle shaft which signal the ECU to activate the idle circuit or WOT. It has been known to work intermittently (tho it's one thing that I HAVEN'T had to fiddle with on ours). There is also a microswitch on the throttle cable linkage under the air cleaner, and that sometimes does not get compressed when the throttle is released. Don't know if it was on an '88.

Steve

I have that switch and it tested fine.
The dam car almost killed me this evening. It stalled as I was making a right turn and traffic was coming at me.

Stall.....
 

Hi,

Sudden Stalling Syndrome (SSS) is a Safety Issue, so be carefull where you go play with the car until you get this issue solved.

I follow this thread since day one, on one of your post you mention duty-cycle 50% EHA +/- 1mA wich is perfect.

My question here, how a car with perfect on/off ratio and perfect EHA reading might stalled???

1- Lost power at the CFI module or at the fuel pump, again thumble all the component behind the battery to try to reproduce your stalling issue at idle.

2- Your Hall Effect Sensor is given bad reading to the CFI module.

3- Your temp. sensor have a bad warming curve.

Since you already swap the coil, the ezl, and the crank sensor, to me this is what left, according to your ON/OFF ratio and EHA reading.

After stalling does the car start right back or do you have to wait ?

Do you have to floor the throttle to get it running after she stall ?

When it start back does the RPM surge from 500 to 1500 RPM ?

Hope this Help

- Max

Thanks Max,
when the car starts first thing before I go to work it goes to about 900 rpm, NEVER above 1000 rpm. If I sit in the car waiting for it to warm up it will sometimes stall. It will immediately start back but sometimes I have to hold the throttle or it will stall back.
I went ahead this morning and lightly hit all relays and the computer while the car was at idle and that didn't produce a stall.
Let me repeat an observation: When I push on the throttle (give more gas) while the car is in idle it will backfire.
Oh, the temp sensor wouldn't be the problem because my old one and the new one never cured the stall (statistically speaking).

I just finished doing some adjustments, so before I knocked the tower ball out to reach the fuel/air mixture I remeasured the fuel pressure and monitored the duty cycle.
http://i713.photobucket.com/albums/w.../wIMG_7259.jpg

http://i713.photobucket.com/albums/w.../wIMG_7261.jpg

http://i713.photobucket.com/albums/w.../wIMG_7260.jpg

http://i713.photobucket.com/albums/w.../wIMG_7267.jpg

I then drilled the ball out and adjusted the fuel mixture a tad richer but that didn't influence the idle at all. What's up with that? I did see the duty cycle change to the rich side but that's about it.:confused::confused:

Anyone???????????????

your thinking way past this....just tune the damn thing up and see if that works...hall effect sensors and such...come on...Sudden Stalling Syndrome? Please, that is foolish talk, just put some simple parts on the damn thing and start there, this isn't a Space Shuttle you are talking about...What is the Hall Effect? Tell me that....

Didn't I started this thread with comment: only if you know what you're talking about? If you have a solution or a positive suggestion then please, by all means, do share. Oh, I happen to be a space cadet :P:D

EHA adjustment results
 

Since the air fuel mixture tower adjustment had no effect, I went ahead this time and adjusted the EHA.
The first shot shows the set up where I monitor the rpm via the main ignition wire, the voltage on pin three set on DC to read the average effective voltage and the scope to watch the waveform as it actually changed from lean to rich. Compared to the previous results I was able to enrich the mixture this time by changing the EHA setting. In effect I increased the pressure between the upper and lower chambers of the fuel distributor.

http://i713.photobucket.com/albums/w.../wIMG_7269.jpg

http://i713.photobucket.com/albums/w.../wIMG_7272.jpg

http://i713.photobucket.com/albums/w.../wIMG_7275.jpg


Oh, and the car still stalls while at idle:mad::mad:

Clearly my problem is NOT with fuel pressure or any CIS related Item.

The only good news that I can share right now is that the car is NO LONGER BACKFIRING!

Well here is some good news: all that tweaking yesterday may have fixed the problem. This morning the car started right up and it never stalled while idling or on my way to the junkyard to get some toys. Let's see how it does tomorrow in traffic on my way to work.

Observations:
Smooth and stable idle
No oil pressure fluctuation
No severe vacuum reading losses at the economy gauge
Car accelerates very well
No backfiring
NO STALLING... for now

I'm pulling for you Drew. Quick question, when you checked your fuel pressure, how was the leak down? Did the pressure hold when you turned of the fuel pumps?

Dave

Yes the pressure held and nicely and slowly went down until I purged it so I can unhook the CIS tool.

Update:
The car so far hasn't stalled since I fiddled with the pressure adjustment for the EHA and the fuel mixture at the tower. As matter of fact it seems to have picked some extra power:D while idling very smoothly.
I also noticed that it no longer backfires, the oil pressure gauge does not fluctuate as wildly and I think this is important, the fuel economy indicator is no longer at or over 1/4 from the left when I am at a stop in gear; as matter of fact it's almost at zero.
I tested the car in Washington DC and Baltimore traffic during rush hour :mad::D but it's all good:D.
Let's see if it holds up for the rest of the week:rolleyes:

Give my regards to Gilligan and Mary Ann
 

I knew you could do it.

:vbac47679
I feel fantastic, that's for sure.

I want to thank Larry from CIS Flow Tech for his instructions and Germanstar for setting us up. Those are real good guys in the Benz community (and Ferrari).
Thanks Larry!

http://www.germanstar.net/forum/index.php/topic,26.0.html

That is encouraging news!!! I am virgin Mercedes owner with my newly purchased project car an '87 109E 2.3-16. I was watching your thread here. I am very happy to see you got it fixed. Way to go!:thumbsup:

Do you have any more pictures of you testing the fuel pressure out? I am lost as to where or how you get the differential pressure, or what it even is for that matter. As far as I know, you test fuel pressure by installing a gauge w/fitting as in the 2nd picture, but your first pic also has me thrown off. What is the correct procedure?:confused:

Connect one end like you see in Picture #2 to the test port for the lower chamber. Connect the other end to the upper chamber via the cold start outlet on the fuel distributor. If your EHA is functioning properly you should get a differential of .4 bar while pressure is on. The put pressure on the system remove your fuel pump relay and bypass the connectors to get the pump to run.

Another way is to read the upper chamber alone, then connect to the lower chamber and subtract the results. This is acceptable if you have a simple gauge with a single test line.

Ah ok, thanks! I believe you posted (somewhere) that you obtained your set up from Harbor Freight, if so, is it this http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=97706 ? Are there any adapters/fittings that will fit the CIS system. I don't mind checking one chamber at a time.

That's the exact kit and all fittings are included.

Update:
It's been a month and the car hasn't stalled or even hinted a hesitation. It's running very smoothly and I haven't noticed a drop in gas mileage; I am still getting 28-30 Highway and little less in the city.

It Stalled! BADLY!!!!!!!!!!!!

As soon as I started the car an hour ago it died. I started it and it stalled OVER AND OVER until it held. I drove to the store where I was going and it stalled at traffic lights while stopped.
As soon as I got home the car stalled WHILE IN MOTION and coasted to its parking spot.

I have failed in a monumental way. This car is truly a piece of ... :mad:

I've read too many posts and some say cps is in the front and some say it's in the back.. In looking to fix my stalling problem but I can't figure out exactly where the part is that needs replaced. Its the tdc crank sensor that needs replaced and if I can get some descriptive instructions and maybe some pictures I would really appreciate it.. Any help would be very much appreciated.
Thank you for your time.