My 300E has had a hard start problem for quite some time now. From cold, it takes about 5-10 sec. of cranking and pumping the throttle to get the engine running. Unless I rev the engine a bit at startup, it will run rough for a short while. Once running, however, the engine runs very nicely... for a while at least. The hard start issue returns if the car is turned off for more than about 30 minutes. In fact, it's often worse if the engine is still somewhat warm. Any thoughts?
Once the engine is thouroughly warmed up, another thing happens... the engine begins to run rough at low RPMs when driving. It is most noticeable when acclerating from a stop, and is especially pronounced when I punch the throttle from a stop. The engine smooths out as the RPMs climb in 1st gear, but the stuttering returns when the transmission up-shifts and the RMPs drop again.
Any thoughts?
Thanks so much!
Mika

Search for Water Temp Sensor. The same info regarding it in a W201 with an M102 or M103 motor will apply to your 300E.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

THanks; I will test that sensor tonight.
Could these symptoms also be caused by old / leaky fuel injectors? That was suggested by two mechanics independently, but has not be confirmed by anyone on this forum. Sound legit?
I've run some injector cleaner which seems to help at first, but the improvement is marginal at best, and doesn't last long. Could be coincidence.
Mika

there is a post about hard cold starting in the 124 about once a week. Instead of typing in my stock reply of a couple of suggestions I'm just going to suggest you do a search for posts under my name and you will find some suggestions.

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car

Could be, but every MB Tech I talked to said the injectors are hard to kill on these cars. I replaced mine and found it did nothing, then again my head gasket was shot before and my Pre-Cats were clogged as well. But now at least I know they are new. I have replaced that Water Temp Sensor 3 times on mine, but two of those were because I broke it. Damn wrench slips. But when I did replace it my car started better warm and cold and seemed to do better all around.

__________________
~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

I tested my water temp sensor last night. When the engine was cold, I measured about 6600-Ohms across the terminals, and exactly half that amount from each terminal to the frame. At operating temp (dash gauge showed about 70C), I measured about 860-Ohms across the two terminals, or 430-ohms from each terminal to the frame.
Can anyone confim if the posted temp vs resistance values on this forum are for each side of the sensor to ground? Here's the chart I found:
Temp Celcius ---------Resistance KOhms
-20-------------------15.7
-10-------------------9.7
0---------------------5.9
10--------------------3.7
20--------------------2.5
30--------------------1.7
40--------------------1.18
50--------------------0.84
60--------------------0.60
70--------------------0.435
80--------------------0.325
90--------------------0.247
If so, then it seems my sensor seems pretty close. Do these values seem good to you?
Mika

-20 15.7KOhm
-10 9.2KOhm
0 5.9KOhm
10 3.7KOhm
20 2.5KOhm
30 1.7KOhm
40 1.18KOhm
50 840Ohm
60 600Ohm
70 435Ohm
80 325Ohm
90 247Ohm

Next time please search. Luckily I was bored at work and found my old post with the table. It is read from the tip to ground not pin to pin!

Edit: Hey you beat me to it damnit!

__________________
~Jamie
_________________
2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....