84 190E Idle issues

[dieselnutnj]

Greetings!!!

Have a 190E I am narrowing down my idle problems with. Another member said check the OVP fuse, the 10 amp which I did from the get go, I forgot to mention that. I've cleaned the IAC, and I can make the idle change by moving the adjustment knob, but once I get the idle decent on cold idle.. its up around 1500 rpm when hot.

On the front of the cylinder head, on the intake side are three sending units. The first has two terminals on it, second one ,has one and the third one. The first one, makes no effect if disconnected hot or cold. The second one makes a huge difference when disconnected, especially hot. When hot.. the engine rpms drop.. but it runs extremely rich. THe third sending unit is for the aux fan as far as I can tell. Here is the readings I have:


First unit *two prong* a- cold infinity hot- 13meg ohms
b- cold 95 ohms hot- 95 ohms

between a-b pins cold infinity hot 21 meg ohms

the first measurments are with respect to the cylinder head or ground.

My question for this one is.. does this unit have two seperate sensors to ground in one unit.. or is the change supposed to be between the a-b pins.

being this is a 100.00 sending unit. .I'd just like to know what a working one reads.

I'm pretty sure the second sending unit *middle one* is functioning as it should.. cold I have a reading of 1.6Kohms and hot its down to 257 ohms


Did I confuse anyone? Thanks in advance for the help.. so far it's been amazing the techno info on this site!

73's
Rick
W2ICA