Cold Start Problem 300TE
 

I purchased an 88 300 TE with 272 k miles on it in August and its been fine for me until recently with the cold weather. It won't start but gives every impression it wants to. Plenty of crank and a sounds like its ready but won't hold the rpm s. When I was finally able to get it going the temperature outside had risen significantly but the car felt like it was running on 3 cylinders. My mechanic, who's not a big Mercedes guy, seems to think that a block heater should resolve the problem but that assumes I plug it in at every stop. I noticed that a cold start valve is an available part but don't have a clue. Maybe just a tune up? Any thoughts would be greatly appreciated. By the way, it will remain cold in these parts of Idaho until April.

A block heater is not necessary and would be a PITA. You really need to seek out a mechanic who understands the Bosch CIS fuel systems. You could have a cold start valve problem, but I rather doubt it. The failure rate on that circuit is very low. Wilthout having the car in front of me, I'm suspecting a faulty signal from a temp sensor or the car isn't operating off of the computer for some reason. I'm sure your mech has taken care of your other cars, but it isn't fair for either one of you to ask him to diagnose this car.

Post Script: Thank you very muck for posting exactly the year, make, and model of the car you are asking about. One of the pet peeves of the professionals on this site which sometimes means no answer to the question is yahoos who insist on keeping that information a closely guarded secret. One of the pros here always asks:" Is this A Ford or A Chevy."

Thanks for the feedback. Appears I may have found a local familiar with these systems. We'll see next week when he gets to it.

Good luck, and it would be nice if you post the answer.

Peter

Still haven't gotten it to the mechanic he's very busy. So I've been making an attempt to look under the hood and noted that the Breather Hose to the air filter is barely attached to the manifold and the thin hard plastic tubing (vacume hose?) which attaches to the bottom of the Breather Hose is broken and brittle. Last but not least, the Air Intake Hose is split in half. Think any of this may have an impact on the car's inabilty to start?

By the way, where does that thin hard plastic tubing go? I've been tempted to pull the entire air filter housing to see but until it stops snowing or I tow it to the mechanic I think working on it under the current scenario seems a bit masochistic.

Any thoughts would be greatly appreciated.

Air intake hose makes no difference, but hoses to valve cover are quite important. See
http://www.peachparts.com/shopforum/1029163-post2.html

Still waiting on a spot for the mechanic to look at the car, but was curious about the location of the air temp sensor or better yet, is there somewhere I can look at a diagram of the air and fuel injection system with part numbers or descriptions? I've was told that the CD manual is not a very good source but are there any other alternatives?

Check the Water Temp Sensor. It tells the CIS-E controller the Engine Temp and is what tells the CIS to fire the Cold Start Valve and also to regulate idle, to raise, for proper warm up. When that sensor fails the CIS system thinks the engine is warmer than it is and thus does not provide enough fuel or idle control.

Do you have a part number for that Water Temp Sensor? I've been getting info that there is more than one.

Thanks for the info

Click on the "FAST LANE" tab at the top of this page. Enter your year/make... then selech your model. The _Catagory_ is "+Fuel Injection" and the part is called... "Water Temp. Sensor"
or just click this link :)
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1OH0MY2181OH0MYQHF&year=1988&make=MB&model=300-TE-001&category=C&part=Water+Temp.+Sensor&appEngines=_any
Your existing sensor should be tested for proper resistance before it is replaced (no need to throw dollars [though not too many in this case] away unnesessarily)
Should test as follows:
Ohm's range from the temp chart in the /Engine Manual-Combustion Manual-07.3 Mechanical/electronic gasoline injection system (KE injection)-121 Testing electrical components of KE injection system. page 60

Temperature °C........Resistance kΩ
-20........................15.7
-10.........................9.2
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
Same resistance values apply to KE intake air temp sensor.
I think this chart applies to these 2 sensors for all KE systems but don't know for sure.

Invaluable

Thank you

Back to it

I'm not sure what year we are dealing with??

Has the engine been tuned-up lately? Maybe check the spark plug wire resistance, replace plugs, inspect rotor/distributor might be in order.

These engines are quite reliable, but on a 20 year old car may need some diagnosis to get it sorted out. I'd start with the temp sensor, then you can check the function of the cold start valve, OPV relay, fuel pressures and try and work things out.

What year is this car?????????

Michael

kirk333 is one of the few new posters to include year, model, and location in his request for help. Now the old posters just need to take time to read the info provided.:D

Damm- missed it in the first sentence!

Sorry about that!

Again thanks for the feedback. Hopefully I'll have an answer to this by next week sometime.

I can't understand how someone could attempt to seek advice in this arena without providing year make and model. Are Mercedes that similar between years and models?