W124 300TE cold start problem - PeachParts Mercedes-Benz Forum

farmbenz · #1 06-24-2009, 10:34 PM

Hi, I'm having ongoing and intermitant cold start and cold running problems. About half of the time car will not start without throttle and will not idle on its own. After a few minutes it suddenly gets happy and is fine after this. Smells rich when it has problem and fuel mileage is not as good as it has been.
Is there a temp sensor that has a habit of being intermittant? Car has KE3 injection and no catylist and no closed loop control (as standard UK spec).
Thanks if you can help.

Farm Benz(s)

cliffmac · #2 06-24-2009, 10:58 PM

you sure KE-5? my 1990 has the KE-5 and was doing that last summer...it was solved by replacing the coolant temp sensor (which was totally screwed upon removal) and a new set of the new Bosch Copper-Pluses, thing runs great, has since then. About $60 out the door

farmbenz · #3 07-01-2009, 02:50 AM

Hi cliffmac, The injection system is KE3 as far as I can tell from the Workshop Info System. You say you changed the coolant temp sensor. Which one is that? There are a few temp sensors and I was trying to narrow it down a bit and not spend unnecessarily.
Cheers, Farmbenz.

Ivanerrol · #4 07-01-2009, 04:04 AM

Here 'Tis
At rear of engine

pawoSD · #5 07-01-2009, 11:51 AM

Replacing that sensor on my car helped it out a lot too.

farmbenz · #6 07-07-2009, 07:59 PM

Thanks for your help!
The winner is the OVP relay. Somewhere someone suggested this may be a problem so I removed it (located next to one of the ECUs) opened it up and found dodgy solder joints. I desoldered these and resoldered them and so far (2 weeks and about 56 starts) it has worked well with no repeat of the problem.
Thanks for your suggestions!
Farmbenz.

cliffmac · #7 07-07-2009, 08:45 PM

yep, that's the right sensor. when I pulled mine out last summer the tip was coated in calcium deposits..totally white...changed it and threw a new set of Bosch Copper-Pluses in $60 out the door and it was like I had installed a brand new engine...really, that dramatic...changed the whole complexion (and my regard) for the entire car...it really was dramatic..best of luck...cliff

cliffmac · #8 07-07-2009, 08:54 PM

no, upon further inspection it's the one in back of the one that's unplugged, that big one in back of the one that's unpluged. That's where my coolant temp sensor is located, I don't even have the plug in the picture..but I have an absolutely base 1990 300TE with no options at all as far I can tell. I wonder what that other one is for...I have no heated leather seats, 4-Matic, traction control...nothing..just a regular 2 wheel drive 300TE. Let me know what that is because I think the plug behind that one pictured is the coolant temp sensor...hmmm...interesting...cliff

cliffmac · #9 07-07-2009, 09:01 PM

or maybe that's just the connector laying loose next to the sensor after being disconnected, in that case, my error....yeah that's the coolant temp sensor there....$35 but kind of goofy to install, you need like a thin walled deep socket to actually get her in there properly, and for sure use plumbers tape (teflon) on the threads...but I bet it'll make a difference..it'll eliminate the hard warm start and stalling after warm issue right away. Doesn't make any difference on cold start cause it hasn't kicked in yet but after that...big bang for the buck....cliff

Cal Learner · #10 07-08-2009, 07:57 AM

Quote:

Originally Posted by farmbenz

Thanks for your help!
The winner is the OVP relay. Somewhere someone suggested this may be a problem so I removed it (located next to one of the ECUs) opened it up and found dodgy solder joints. I desoldered these and resoldered them and so far (2 weeks and about 56 starts) it has worked well with no repeat of the problem.
Thanks for your suggestions!
Farmbenz.

Nice going farmbenz. Just another reminder to us all that the OVP should rightly be suspect #1 whenever you have any sort of engine mystery on your hands.