Cold starting trouble

[mcdill]

My car has been hard to start lately when it has been sitting for a while. Its idle when cold seems too low also, and has stalled a couple of times from the low idle. It will idle between 450-500 rpms when first started. When it warms up, the idle is fine. I went up to Tahoe over the weekend and when I came out in the morning to start the car, it didn't turn over for 2 cranks, then on the 3rd, I pushed the gas down a little and it finally started. Since then, I have had to push the gas down to get it started several times, but only when it has been sitting for hours.

My guess is that it has something to do with the fuel pressure or some cold start valve/component. Anyone able to help out?

THanks,

Matt
1994 E320 150k

[zorin]

There is a Cold Start Valve that opens up when the coolant temperature is below 15 degrees C. This valve is controlled by ECU providing that the coolant temperature sensor is sending the correct info to ECU.

- Make sure that both connectors off of the sensor are in good condition
- Check the Sensor
- Check spark plugs and their wires condition

[mcdill]

Where is this valve located?

Thanks for the info.

Matt

[zorin]

On my 300E it is right beside the Fuel Distributor close to the engine block (See photo) It has a pale green top.

[zorin]

Attaching photo (2nd attempt)

[jsmith]

i have the same problem. mcdill has an m104 engine which is different from the one depicted. i have not been able to verify that there is a cold start valve in these engines. i also discovered that there is no fuel accumulator either ...

[mcdill]

My car used to hold second gear longer until the coolant hit 60 degrees, but it no longer does that... is that related to the symptoms that I'm having/cold start valve?

In the summertime when I turn on the air conditioning, the idle sometimes dips below 500 RPMs, kind of like the same problem that I'm having now, except that the engine is now cold instead of hot.

I'll have to dig around the engine after work today to see if I can find a cold start valve or something like it.

Thanks,

Matt

[jsmith]

the second gear delay is controlled by the upshift delay valve. some consider it a big nuisance myself included

[ako]

Originally posted by zorin
On my 300E it is right beside the Fuel Distributor close to the engine block (See photo) It has a pale green top.

Zorin or anyone,

How do you test whether this cold start valve (pale green top) is defective or not?

My 300 TE would "sometimes" have a rough cold start for only the first half second to one second of cold starting in the morning. But after that, the idle becomes smooth. When engine reaches operating temperature, the idle settles a little bit over 500 rpm and is still smooth. I do notice that my gas consumption is only about 18 mpg of combined city and freeway driving.

Thanks,
R.V.
--------------
92 300 TE (m103) 114K miles

[zorin]

First you need to test to see if ECU turns it on . Second , test if the valve actually opens:

Unplug the top portion (you have to take out the wire strap around it), have someone crank the engine. The voltmeter should show non-zero voltage at the end of the plug while cranking.

To make sure the valve opens you actually need to unplug the fuel line from the valve, unscrew the valve, connect back the fuel line to the valve and have someone crank the engine. The valve then should open and inject fuel for couple of seconds.

Just a reminder that the valve kicks in when the "coolant Temperature" is below 15 degrees Celcius.

[mcdill]

I'm pretty sure that my problem is not the cold start valve, since I had the problem the other day in 60-70 degree weather. My idle fluctuates a lot while warming up, and when switching gears into drive or reverse from Park, the idle dips below 500, which causes the car to be very unresponsive at low speeds, to the point of almost stalling. I'm still guessing fuel pressure....is there anything in particular to look for?


Thanks,
Matt
94 E320 150k