1994 C280 - Consistent Engine Cutoff after 20+ mins & Crank No Start after that till car cools overnight. Warm Engine "Crank NO Start"

[Arv]

Hello,

1994 C280 Consistent Engine Cutoff after 20+ mins at any speed & idle
& Crank No Start after that till car cools overnight.

Warm Engine "Crank NO Start"

NO Engine Light on.

When "Crank No Start" happens,

1. Tested Fuel Relays on the table by applying voltage & they work as expected.

2. Also tested by installing both relays back on the car and having someone crank while I was
hearing the click and feeling the click by putting my hand on BOTH Green relays,
one in fuse box and one in the trunk.

3. Tested the Fuel Pump also by having someone crank and I went under the car
to hear & feel the pump running.

4. Also tested that fuel is reaching injectors at the Schrader Valve by slightly
pushing the pin of Schrader Valve down (like we release bicycle or car tire air)
and watching the fuel spray out instantly.

5. Haven't tested the pressure with gauge or a syringe test yet by removing
fuel rail and also watching out for non-continuous fuel spray.

2 yrs ago, I had replaced Crankshft and Camshaft Position Sensors.

Is this a sure shot case of Leaky Fuel Injector(s) ??

Help is very much appreciated.

Thank you,
Arv.

 

[ajlsl600]

Crank sensor when warm.? Sensors are often suspect from new, if pattern and even if Benz. Don't know on yr model some crank sensors don't stop motor once started some can, heard plenty on warm ones givin up till cold, Alistair might chip in.

 

[LostKiwi]

Classic crankshaft position sensor issue.
Only fit Bosch or genuine.

 

[AMGeed]

^+1

 

[mioba]

as LK.
Having owned mercs for many years and keep them for a long time, I have learned that mercs and aftermarket parts just dont work well together.
Had original parts last 12 odd years, replaced with aftermarket and they fail within a couple.
Buy once buy right.

 

[Arv]

Thank you all for your help.

I had engine cutoff issue once before long time ago but
the car used to start right away. Didn't have to wait for
complete cooling down. Even if the coolant temp comes
down to 60 deg C, still doesn't start.

Engine cuts off ones the coolant temp reaches normal
operating temp of about 90 deg from cold start in about
20 mins or so while car is parked. Not driving it bcos of prob.
Last time this happened, it was completely random and not
consistent like this time. That's why I thought may be a leaky
injector may be a problem.

Since I had replace CPS sensor 2 yrs ago, I didn't think
it could be a problem. I believe it was OE Replacement.

Will look into this.

Thank you all. Appreciate your help,
Arv.

 

[LostKiwi]

My E240 did exactly the same, and my Smart Roadster. Both use the same sensor.
The 240 would happily run for about a mile then die. Wait 30 minutes and repeat.

 

[Arv]

Thanks Lostkiwi. I will definitely check the sensor.

Since it is consistently almost a timed cutoff right after 20+
mins after coolent reached normal operating temp,
I was suspecting a leaking injector since ECU will slowly
reduce fuel supply to all cylinders based on real time
sensor inputs from various sensors.

Excerpt from this Excellent article,

| Rx Mechanic

Read on to learn how to check for leaking fuel injectors to ensure your engine runs optimally and prevent fire outbreaks from external injector leaks and vacuum leaks.

rxmechanic.com

"What will be the outcome of a leaky fuel injector? For instance, your no. three and four fuel injectors are leaking while one and two are okay. What will happen is that no three and four injectors will spray excess fuel into the cylinder. The computer will send a message to the ECM to reduce the amount of fuel the fuel injectors are spraying.

The ECM will not know exactly the injector that is spraying excess fuel, so the ECM will reduce the fuel that all the injectors are spraying. Since the ECM has reduced the right amount of fuel that the non-leaking injectors are spraying, it’ll result in inadequate fuel flow from number one and two cylinders."

Thank you for your help,
Arv.

 

[LostKiwi]

Bad injectors cause misfires not complete loss of power.

 

[M80]

I would expect to see smoke if injectors were over fuelling.

 

[mattkh]

1994 C280 Consistent Engine Cutoff after 20+ mins at any speed & idle
Thank you,
Arv.

A cps sensor induced cutoff would be instant while a fuel related cutoff would be a gradual stall.
Can you describe the cutoff in your case.

 

[Arv]

Bad injectors cause misfires not complete loss of power.

Thank you Lostkiwi. Not complete loss of power is what
i was thinking also but if the ECU gradually reduces fuel
supply, eventually it's going to shutdown the engine.

TO DO today, I will observe more carefully,
set an alarm for 20 mins & run the car for 20+ minutes & stay near the
exhaust pipes to see if I hear a misfire. I will confirm this today.
I think I may be hearing dhrrr,,,, or something like that as engine
cutsoff.

Will let you know a little later,

Thank you,
Arv.

 

[Arv]

I would expect to see smoke if injectors were over fuelling.

Thank you M80. Good point but I certainly don't see any smoke.
But will observe more carefully today while testing it again,

I have also put in Injector Cleaner in the tank on Wed to see if
helps in any way.

Will let you know later on. Thank you,
Arv.

 

[M80]

New CPS aren't overly expensive.
The pleasure of telling us we're wrong might justify it.

 

[Arv]

A cps sensor induced cutoff would be instant while a fuel related cutoff would be a gradual stall.
Can you describe the cutoff in your case.

Thank you mattkh, good point also. It certainly is instant.

Is there any way to test Crank PS before ordering a new one?

What should be it's resistance if working properly? But again,
resistance can change a lot on a malfunctioning sensor when
warm/hot. I will check it when cold and then after engine cutoff.

Not easy to access & Damn things are not cheap either.

Thank you,
Arv.

 

[Arv]

New CPS aren't overly expensive.
The pleasure of telling us we're wrong might justify it.

They are anywhere bet $50 to $250+. I will check the price
today.

 

[M80]

When the car is running you would expect the sensor to read correctly,
Run it till it cuts out then you might see a jump in what ever reading.

Are there no historic codes?
Is the car too old for that?

 

[Arv]

When the car is running you would expect the sensor to read correctly,
Run it till it cuts out then you might see a jump in what ever reading.

Are there no historic codes?
Is the car too old for that?

Thank you for your reply. I had this problem since last Nov or so
if I remember it correctly but it was very intermittent and the car
would always start after some time.

Recently for last month or so, it started happening more regularly
with Engine Light ON, checked the codes with a very basic OBDII
scanner I have and got,

P0101 Mass or volume air flow circuit range/performance problem (Hot film MAF sensor)
P0170 Fuel trim malfunction (self adaptation of fuel mixture) -
P0441 EVAP without function (logic chain)

Fixed all these 3 codes so now engine light is NOT on and now it
happens consistently after 20+minutes and Crank NO Start till
car completely cools down. Doesn't even if coolant temp is 60 degC.
Has to cool down completely.

Thank you all, will let you know after today's test again.
Arv.

 

[Arv]

They are anywhere bet $50 to $250+. I will check the price
today.

Crankshaft Position Sensor
$159.00
Mercedes-Benz of Miami
Part Number: 003-153-75-28-64
Other Names: Crankshaft Sensor, Sender Unit, Sender Unit
Replaces: 003-153-73-28, 003-153-75-28
Description: C280. E320. C220. Sl320. 300ce. All models.
2.8L, inline.

Search Results | Mercedes-Benz USA Parts

mbparts.mbusa.com

I still have the old sensor and it shows part numbers
015 545 28 28 on Connector itself and 0 261 210 085 on Sensor
at the end of wire. Hmm...

Thanks,
Arv.

 

[Arv]

Problem Solved.

Thank you, thank you to all of you for pointing me to right direction.
Sorry that I couldn't reply yesterday as promised because got rained out.
So had to work on it today.

The problem was the Crankshaft Position Sensor round connectors. The round
male/female connectors just slide & press fit with no latch to hold them
in place. I had replaced with an OEM sensor about 2.5 yrs ago. It must have
gradually loosed that after it got warm/hot after 20+ minutes of running
the car, it probably was not making good contact.

As soon as I removed & connected them again with little force, the car
started and tested it 7-8 times with engine hot. Started immediately,

Now I tied the 2 connectors firmly together with a wire so no loose
contact develops again.

Gave me lot of grief for a while because of this poor design on the part of mercedes.

Just curious,
1. How much should be the resistance of the sensor?
2. how much should be reference voltage with the key on?

Really appreciate all of your help.

Thank you,
Arv