190E low idle when cold - PeachParts Mercedes-Benz Forum

pentoman · #1 11-11-2004, 01:12 PM

Hey all,

Can we have a very simple explanation of the cold starting procedures of the engine here please?

There's a lot of posts if you search, but it's heavy reading and very confusing. All I know after reading it is:

There is a water temp sensor, its readings measured with a multimeter should be:

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

Apart from that, I know there exists something called an EHA (Basic explanation of what this does?) which can be adjusted.

and a 'cold start valve', is this an actual valve? Is it part of the EHA? does this enable 'cold start enrichment'? Should you get a higher cold idle even if your tuning is way out?

This is for M102 190E, 200E, 230E four cylinder (and M103 six cylinder?)

My car when cold idles at about 750rpm (too low), stumbles, and will stall very easily. It actually starts fine (after 1-2 seconds), though is best of with a bit of gas.

I've had it tuned up right, but it just seems the part that gives me a decent higher idle when cold is missing.

Tested my water temperature sensor, it reads: 8 KOhm at cold (5 degrees air temp) and 600 Ohm engine warm (80 degrees engine temp on interior guage), which seems about right. Unplugging the plugs from this sensor makes the engine stop, so it seems something is reading the sensor. The question is, shouldn't it be making the engine idle higher when cold?

Russ

mctwin2kman · #2 11-11-2004, 04:02 PM

EHA is Elctro-Hydralic Actuator. It is mounted on the side of the fuel distributor. This is really what adjusts the pressure to adjust the mixture. The Idle Air Control Valve is what raises and lowers idle by allowing less or more air into the intake bypassing the AFM, Air Flow Meter, and going directly to the throttle body. It opens and closes to adjust air flow. It is in between the last two intake runners under the air box. The Cold Start Valve is the only electronic Injector there is. When cold, below 60 degrees, this fires a burst of fuel into the intake manifold to assist in cold starts. Only fires once before starting. Then you have all the electonics that work this crap. You have that temp sensor which tells the CIS-E controller to fire the cold start and also cycle the Idle Air Control Valve as well as the EHA control. As the engine warms the EHA leans the mixture, and en-richens when cold. You issue may be the cold start valve needs cleaning as well as the Idle Air Control Valve needs cleaning. The Idle Air Control Valve also could be shot, or your switch on the throttle linkage could be bad as well. The switch on the linkage lets the IACV know when you are not on the gas and thus Idling, which is the only time the IACV is actually doing anything.

mike65 · #3 11-13-2004, 08:02 AM

I had this problem on my 2.0 190e, it was fixed by replacing the water temp sensor.

Mike.