560SL hard cold start, ok when engine warm - Page 2 - PeachParts Mercedes-Benz Forum

meltedpanda · #16 02-08-2017, 01:53 PM

what are your system pressures and rest pressures?
Is this an after market fuel pump or OEM

grigorean · #17 02-08-2017, 02:52 PM

I have 2 new Magnetti Marelli pumps.System pressure 6.4 bar, Lower chamber pressure 6 bar. Pressure drops to 3.3 bar after stoping the fuel pumps.Fuel flow was also tested, 1 liter in 40 seconds.

Thanks

optimusprime · #18 02-09-2017, 06:32 AM

Did you replace the engine temperature sensor .This item helps to switch the cold start system on .It sends a message to the ecu to say yes i am cold so i need more rich fuel.But if the sensor is faulty can tell the ecu i am hot and at normal temp so i need lean fuel to run.

grigorean · #19 02-09-2017, 07:21 AM

Cold start injector receives signal, and also cold start injector is working good, that is why I exclude the coolant temperature sensors.Also Idle air valve is working.

Diseasel300 · #20 02-09-2017, 09:45 AM

The engine temp sensor shouldn't have anything to do with this issue since it's still running poorly when warm!

grigorean · #21 02-09-2017, 11:15 AM

The day after tommorow I will receive the intake gaskets and I will put back the intake on engine.But until then, I am still affraid that this small leak that I have found, is not the source of my problem.What do you think?what else can be?
for me is a little bit crazy, since I have fuel, I have air, I have spark, but engine still not running, only after I help it with ISO Octane for 5 seconds...

Diseasel300 · #22 02-09-2017, 06:05 PM

You may have air and spark, but you have the incorrect *AMOUNT* of fuel entering the cylinders.

optimusprime · #23 02-10-2017, 05:47 AM

Quote:

Originally Posted by Diseasel300

The engine temp sensor shouldn't have anything to do with this issue since it's still running poorly when warm!

If sensor is stuck on cold start then it will richen the mixture up , so bad hot starts only . The ecu gets the information from the sensor .

Diseasel300 · #24 02-10-2017, 10:06 AM

Quote:

Originally Posted by optimusprime

If sensor is stuck on cold start then it will richen the mixture up , so bad hot starts only . The ecu gets the information from the sensor .

Except that the OP has already tested the CSI and found it operating.

grigorean · #25 02-10-2017, 12:22 PM

Quote:

Originally Posted by Diseasel300

You may have air and spark, but you have the incorrect *AMOUNT* of fuel entering the cylinders.

And how should I solve it?I am thinking to get the control plunger to the 0 position based on some information that I found about fuel distributor repairs, and after that to modify the 3mm screw position until I will have a play of 1 mm at the air flow plate when the fuel pump is activated and pressure builds up in system.And after that I think it should start, even if afr is lean or rich, because the play between control plunger and airflow plate should be between 1-2 mm, and I think that between this values is made the adjustment of mixture.

any opinions ?

Diseasel300 · #26 02-10-2017, 12:55 PM

Before getting carried away adjusting things...

Has the engine EVER run properly since you've owned the car? Looking back in the history of this thread, it appears you had some operating problems due to leaks, then had the engine overhauled. You haven't said if it ever ran right post-overhaul.

I'm assuming you farmed out the fuel distributor for rebuild? If so, was it ever set back up and calibrated on the car? Control pressures checked? If they are off, it can certainly throw off the mixture.

grigorean · #27 02-10-2017, 01:28 PM

the engine was working ok before overhaulin.Fuel distributor was remanufactured by Bosch 1 year before I bought the car.I haven;t modify anything at the fuel distributor.Just tryed to reach a proper mixture.

Diseasel300 · #28 02-10-2017, 01:30 PM

Since overhauling, has the engine ever run properly?

If so, did this cold start issue slowly occur, or did it simply show up one day?

grigorean · #29 02-10-2017, 01:55 PM

thats after overhaulin.Engine never run properly

grigorean · #30 02-13-2017, 02:42 PM

Have changed the intake gaskets.No too much improvement.Still no cold start without spray.After, I tried to adjust the CO screw as much as will start easy at cold.It is ok, but a lot of white smoke, and the idle it is a little bit erratic, and it have a slow acceleration when I press the throttle linkage.Also, the economy needle stays at 1/3 from minimum, at idle.The idle speed is at 700rpm.When I accelerate it to 1000 rpm, the economy needle is very near to minimum.Any idea what to do next?