Question about 1986 Mercedes-Benz 300
I am assuming this is an 86 300 e. first see if you are getting voltage to the cold start valve. this valve is fairly simple although it is hard to describe to someone how to test it and also there are other things that happen when these valves fail. assuming you do not have excessive cranking and you know that this valve is not working i'll just give you the most likley problem. on these earlier cis systems there was a 2 pole tempurature senser( 4 pole in the later version) on the in line six motor. if you look to the intake side of the engine it is the last senser located on the top of the head to the side of the valve cover. There will be 2 seperate wires going to the senser. both the cis and the idle speed computers use this senser. I would usually think the check engine light would be on but these earlier systems are not as sensitive. most likley the senser is giving false info to the cis unit which grounds that solonoid(cold start valve). take a ohm meter and test each pole form ground to the senser pin. compare the 2 readings. I know the 4 pole sensers cannot be more than 10 ohms differense. To make things easier on yourself just get a new senser and install it with a new crushwasher. ask for the pcm engine coolant temp. senser. The other sensers are used for your gauge and aux. fan.
Posted on May 17, 2009
You need to check all the factors that can affect cold start.
Check the AIF Sensor, check the air intake and the air filter. The air intake sensor can also affect cold start.
Also check your spark, and have a code reading done at your garage to scan car computer, this will tell more on the fault.
Posted on Mar 07, 2009
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