Car dies and may or may not restart
 

My '92 190E 2.6 began intermittently stalling at start up after driving when put in drive. It would start up and go after a short wait on those occasions when it stalled out. Yesterday it died going down the road after 5 miles and would not start. Had to have AAA flat bed me home. Today it started right up but I'm afraid to drive it. I'm thinking OVP? fuel filter? Ideas anyone?

I would suspect the Oxygen sensor. When was it replaced last?

O2 sensor in absolutely no way cause the car to stall and not re start.

You are losing fuel, or spark. Start the car and let it warm up. When it starts to stumble, check fuel pressure. You can get a cheap fuel pressure gauge at harbor freight. Next, pull a wire and ground it out. Chances are you will only see a small spark.

The symptoms you are explaining sound like a classic bad cap and rotor.

A faulty Oxygen sensor could certainly cause the engine to stall after driving only a few miles. I have experienced that exact scenario. By all means check the condition of the distributor cap and rotor. Recommend Bosch parts as replacements. You may want to replace the distributor cap O-ring while you're at it.

Hot dirty injectors are inclined to not work well.
Have you cleaned them recently ? Even with a can or two of 'in the tank' stuff like Lucas ?

So you are telling me that a faulty o2 sensor would cause a car to stall and not restart until cold again?

What I said in my previous post is that a o2 sensor would not cause a car to stall AND not restart.

Symptomatic of a faulty Fuel Pump Relay.

When your car stalls, remove the F.P.R., give it a bit of a tap and see how you go.

F.P.R.'s and O.V.P.'s are trouble spots for these cars.

Eugene, in Post #4 I corrected my previous statement. I say nothing about restart.

I would go with troubleshooting the OVP or the fuel pump relay. I am currently driving around with my o2 sensor disconnected while I am waiting for parts on my 124. the duty cycle with the o2 sensor disconnected is just about 50%. This is not recomended because the o2 sensor does the fine adjustments of the mixture,and with it disconnected it is steady no computer controlled fine mixture adjustments.

A KE injection car will run without the O2 sensor connected.
You can even remove the ECU - the engine will still run - although you will have no idling adjustment.

The ECU only regulates the mixture control via the EHA judged by the O2 sensor.
It also controls the idle via the throttle position switch, and the throttle position sensor.

The main issues with stalling are the Fuel Pump relay and the Crank Position Sensor.
The crank position sensor has a nasty habit of working properly when cold and then failing when warmed up.

The CPS can be checked by measuring it's resistance at the EZL connector end - do a search and you will find out how to do this.

Coils can fail however when they go it usually means that the engine will not fire up at all.

Update: My mechanic buddy called me back finally and confirmed what you guys are advising: He thought fuel pump sensor most likely. Distributor cap and rotor also likely because the rotor's resistor goes bad. So I went ahead and ordered FPS(200k) and cap and rotor since they have 30k. He said O2 sensor could cause my symptoms by decreasing fuel when car warms-when car is cold it has rich mixture so car will run. but not too likely because it relatively new (20k). So I'll go ahead and change FPR,cap and rotor. If that doesn't work I'll trouble shoot crank sensor and O2 sensor. I'll update.

My vote is for the crank sensor.

I had mine do that. I had an ohmmeter ready and caught is failing. It turned out to be temperature sensative, I was able to watch it open when warm and close when cool.

Sudden death and not restarting points to OVP.

ovp only controls the "E" in the cis-e system. It would cause rough idle, stalling, but would always restart.

Op, check fuel pressure when the car stalls, then check for spark.

The only things that can cause the stalling when warm with no restart until cold again are:

1. Fuel pump, or fuel pump relay
2. Crank position sensor. Should ohm ok at 1200ohms.
3. Ignition system failure including Distributer cap, rotor, and possibly wires.

Thats it.

Coincidentally I am running into a similar problem on my 420SEL. Just happened all of a sudden. arg. I was on my way to work today. I pulled off the turnpike and noticed the engine rmps drop below 500. I pulled it down a gear, and kept them up for a bit. Then I hit the EZ pass line and had to stop. She stalled and didnt restart. I pulled all the relays, put them back. No difference. I tried to jumper the fuel pumps ON but it was hard to hear if they were on. I wasn't sure which 87 pin was the pumps. I tried all of them I think. One of them gave me a click somewhere in the engine. Maybe something to CIS. Anyway, towed it back home and sure enough it started up at the garage. Oy.

Best I can tell the pumps and accumulator are original at 225K.