Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 03-03-2004, 10:55 AM
Sundman's Avatar
Registered User
 
Join Date: Mar 2004
Location: Umeň, Sweden
Posts: 36
300E Cold starting problems... (-88)

Hello.

I have a -88 300E which is sometimes hard to start when the engine is cold and the outside temperature is approx zero Celcius (ca 32 F i guess). I have to crank it for ten-20 seconds and puch the accelerator until it starts and then the rmp is very low and the engine takes a couple of seconds to reach correct idle rpm... It runs smoothly as soon it has found the correct idle rmp...

When it is colder outside (approx -10 C or colder) it is easier to start it (strange).

I have checked the cold start valve and it works, the temperature sensor for the CIS-injection also seem to work (the resistance is approx the same as the "Haynes" guide tells), the idle speed actuator works, the EHA seems to work to... The spark distibutor and distributor cap and the spark plugs are new ones (changed this winter)... WHAT could possibly be wrong??
I will try to increase the CO-screw to enrich the mixture since the lambda sensor will force the engine to lean the mixture as soon as the engine is running anyway - right? Is this an good idea? Please help me...

I'm getting sick of not finding what is wrong!!!

Can it possibly be the OVP-relay. I've read on som www-page that this could cause cold start problems....

/Ola, Sweden.


Last edited by Sundman; 03-03-2004 at 11:03 AM.
Reply With Quote
  #2  
Old 03-03-2004, 11:31 AM
Registered User
 
Join Date: Jan 2004
Location: San Antonio, Texas
Posts: 46
I had the same problem (and I am still working it). However I did manage to rig a temporary fix that works well for now. I ran a wire from the battery to a push type switch which I installed under the dash and then to the cold start valve. When I engage the starter I just push the switch for a moment and I get instant start. When the Temp is over 60 (f) I don't need this. But it sure saved my butt in January. If I ever figure out why it doesent work on its own I will let you know.
Reply With Quote
  #3  
Old 03-03-2004, 12:15 PM
Registered User
 
Join Date: Jul 2001
Location: SoCal
Posts: 1,303
Monitor your Idle Control Valve voltage. I suspect the valve is gummed up and not responding well until engine heat loosens the internal lubricant. If, however, voltage to the valve is low or null during warmup, the problem is elsewhere. If it is the valve, clean it or replace it.

Steve
__________________
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7
Reply With Quote
  #4  
Old 03-03-2004, 12:55 PM
Registered User
 
Join Date: Jan 2004
Location: San Antonio, Texas
Posts: 46
Mine had no voltage during start or warmup. I had bought a new valve but decided to check the current one before actually replacing it. Now I have a spare.
Reply With Quote
  #5  
Old 03-03-2004, 04:09 PM
Super Moderator
 
Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,318
How did you test the cold start valve?
__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
Reply With Quote
  #6  
Old 03-04-2004, 03:16 AM
Sundman's Avatar
Registered User
 
Join Date: Mar 2004
Location: Umeň, Sweden
Posts: 36
Quote:
Originally posted by ctaylor738
How did you test the cold start valve?

I was using a 10 kohm resistor (between the temperature sensor cable and ground) to emulate cold engine (minus 15 C approx (guess that is ca 0 F). Then I removed the cold start valve and refitted it in such a way that it sprayed out in the open air, then it was obvios that it was working... A fine spray of gasoline in the air (yes I know this i very dangerous....)

Last edited by Sundman; 03-04-2004 at 03:29 AM.
Reply With Quote
  #7  
Old 03-04-2004, 03:23 AM
Sundman's Avatar
Registered User
 
Join Date: Mar 2004
Location: Umeň, Sweden
Posts: 36
Quote:
Originally posted by sbourg
Monitor your Idle Control Valve voltage. I suspect the valve is gummed up and not responding well until engine heat loosens the internal lubricant. If, however, voltage to the valve is low or null during warmup, the problem is elsewhere. If it is the valve, clean it or replace it.

Steve
The voltage changes depenging on engine temperature and the idle rmp seems constant... if I, however, remove the power from the engine (at cold temperature) it lowers the rpm and at warm engine temperature the rpm increases.... So it SEEMS to work fine, but you never know, right?? ;-) ... But you guys think that cleaning the idle contorl valve will fix this? That might be a good idea... I will try it. What kind of lubricant do you need to put in there after cleaning???
Reply With Quote
  #8  
Old 03-04-2004, 03:25 AM
Sundman's Avatar
Registered User
 
Join Date: Mar 2004
Location: Umeň, Sweden
Posts: 36
Quote:
Originally posted by Tigger55b
I had the same problem (and I am still working it). However I did manage to rig a temporary fix that works well for now. I ran a wire from the battery to a push type switch which I installed under the dash and then to the cold start valve. When I engage the starter I just push the switch for a moment and I get instant start. When the Temp is over 60 (f) I don't need this. But it sure saved my butt in January. If I ever figure out why it doesent work on its own I will let you know.
*lol* Funny, I had that idea myself ;-)
Actually I was thinking about doing that, however, I never came to actually doing it, since my "test" of the cold start valve showed me that it was working.
On the other hand, there might be an idea doing such an arrangement, since the problem seems to come and go. Therefore one might think that the problen IS the cold start valve not being actuated due to bad connectrions somewhere....

Last edited by Sundman; 03-04-2004 at 03:35 AM.
Reply With Quote
  #9  
Old 03-04-2004, 09:07 AM
Registered User
 
Join Date: Sep 2002
Location: Atlanta
Posts: 232
I recently went thru the same scenario, on a 1993 300E. Would require 2 cranks to get her going when temp. below 40. OVP was replaced, & fuel pressure was good internally, everything else perfect. Donnie from MB Autowerks got a second look at it, overnight, went thru it, and traced it to the battery . I said no way, it is good. Was about 2 years old, tested fine...until under load. Then it would crap out. Dropped a new 850 CCA Interstate in, and all problems went away.

Simple.
Good luck
Q
__________________
FAQ

W124
Sportline Swaybars
Bilstein HD Struts
16" E420 wheels
Reply With Quote
  #10  
Old 03-04-2004, 09:44 AM
Registered User
 
Join Date: Jul 2001
Location: SoCal
Posts: 1,303
Quote:
Originally posted by Sundman
The voltage changes depenging on engine temperature and the idle rmp seems constant... if I, however, remove the power from the engine (at cold temperature) it lowers the rpm and at warm engine temperature the rpm increases.... So it SEEMS to work fine, but you never know, right?? ;-) ... But you guys think that cleaning the idle contorl valve will fix this? That might be a good idea... I will try it. What kind of lubricant do you need to put in there after cleaning???
No, probably not the cause based on your tests. Could be an air leak, though. Sounds like the ECU is trying to reduce airflow when warm, so it might be coming through elsewhere. Probably unmetered, too, which would lean out the mixture - a real problem when cold.

Also, Q-ball's idea about the battery is worth investigating. If voltage drops too low while cranking, it could upset initial conditions set by the ECU.

Steve
__________________
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7
Reply With Quote
  #11  
Old 03-04-2004, 10:17 AM
Sundman's Avatar
Registered User
 
Join Date: Mar 2004
Location: Umeň, Sweden
Posts: 36
Quote:
Originally posted by sbourg
No, probably not the cause based on your tests. Could be an air leak, though. Sounds like the ECU is trying to reduce airflow when warm, so it might be coming through elsewhere. Probably unmetered, too, which would lean out the mixture - a real problem when cold.

Also, Q-ball's idea about the battery is worth investigating. If voltage drops too low while cranking, it could upset initial conditions set by the ECU.

Steve
I have been searching for an air leak, but I haven't found any (using start gas), but this was never done properly - I will test it again.

The battery is a 88Ah battery (made for the diesel engine cars)and its only one year old so I think that it is almost over powered and ok (it sounds like the starter engine runs at high power), but I can of cource measure the voltage ot the battery while cranking... I've had that idea myself, but never tested it though - or actually I never really believed that that was the problem... but I will try.


Thanks guys! :-) :-) At least I have som ideas now :-)
Reply With Quote
  #12  
Old 03-04-2004, 12:32 PM
Super Moderator
 
Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,318
What resistance do you get across the connectors of the start valve? The spec is 10-25 ohms.

Also, what engine model do you have - digits 4-6 in your engine serial number - 103.xxx? The CD shows at least two modesl for Sweden.

Do you have EGR?

A catalytic converter?

An O2 sensor?
__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
Reply With Quote
  #13  
Old 03-04-2004, 04:32 PM
Sundman's Avatar
Registered User
 
Join Date: Mar 2004
Location: Umeň, Sweden
Posts: 36
Quote:
Originally posted by ctaylor738
What resistance do you get across the connectors of the start valve? The spec is 10-25 ohms.

Also, what engine model do you have - digits 4-6 in your engine serial number - 103.xxx? The CD shows at least two modesl for Sweden.

Do you have EGR?

A catalytic converter?

An O2 sensor?
Yes, I have lambda sensor and catlytic converter, but not any EGR-valve... after the weekend i will have the six digit number of the engine... Ok? (also, my car is originally sold in and importef a few years later from Germany)... I will check the resistance...

Last edited by Sundman; 03-05-2004 at 04:25 AM.
Reply With Quote
  #14  
Old 03-08-2004, 08:54 AM
Sundman's Avatar
Registered User
 
Join Date: Mar 2004
Location: Umeň, Sweden
Posts: 36
The engine is called 103.983 and the start valve resistance vas within specs.
Reply With Quote
  #15  
Old 03-08-2004, 10:18 AM
Super Moderator
 
Join Date: Apr 2000
Location: Falls Church, VA
Posts: 5,318
I think you should run some basic checks on your warm-up enrichment by measuring the current at the EHA. There is special harness that you can use to do this, although you may be able to rig something up.

Here is what the CD says you should be seeing for a KAT engine as of 09-1987:

KOEO: 20 mA

20 seconds after start: 4 - 8 mA

60 seconds after start: 0 to -4 mA. At +20 degrees, the coolant sensor's resistance should be 2.3 - 2.8 kOhms

Temp at +80, fluctuating currrent reading, 230 - 290 Ohms resistance from sensor

My guess at this point is that your coolant temp sensor may be bad and is telling the brain not to enrich.

Good luck. Many posts on measuring EHA current.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 08:35 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2023, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page