saabfan

i have a 1987 16v that has an idle fluctuation about 800-1200 rpm's when warm sitting at a light -thanks for any help

85Cosworth

I have the same problem on my 85 16V. Looking forward to spme input also.

bicylindrico

I recall a 16v with an very erratic idle problem years back. The airflow sensor was at fault. It's easily checked with a DVOM as it's just a rheostat. The resistance sweep should be smooth without dead spots. You typically find a dead spot somewhere around or just off idle.

The idle air valve controls idle speed directly. They are also known to fail often. Try cleaning out with intake cleaner for a cheap repair attempt.

saabfan

i tried to clean the idle control motor but no luck----it also seems to run a little rich--no cat converter if that matters--thanks for any help

saabfan

hey 85cosworth i was doing some research i'm not sure if it helps --does your economy gauge work correctly? (mine doesn't) also at times i would hear hissing when i turned my temp controls off--also seems to run a little rich--if any of this applys check the vaccum feed to the inside of the car ---economy gauge should read about .08 if the needle sits to the right .4 middle .585 to the left --one more thing unplug and clean your air intake sensor----good luck and thanks for any additional input chris

85Cosworth

Economy gauge works. Does seem to run a little rich still. I'll check the air intake sensor when I get a chance. thanks

PhilipM1

Can anyone post pics or give good location as to where all the sensors that control idle/air are on a 1993 190e 2.6? I want to try to clean all mine before I get a Idle acuator thingy. Not to hijack the thread. But that would be a great deal of help. and how amny are there?

saabfan

not sure on the 2.6 but on the 2.3 it sits between two of the intake runners it is about 5-6 inches long with larger diam. hoses connected --on my car to re-install you stick your one arm under all the intake runners and guide the hoses back on---some names are IAC (IDLE AIR CONTROL) or AIS (AIR IDLE SPEED) i tried to clean mine but no change still dances between 800-1200 rpm's. on the 16v there are lines everywhere and its such a noisy engine it's hard to listen for any vacuum leaks--has anybody experienced any common areas to look for leaks--thanks for any input

p rossi

saabfan, hows it going. have you tried to adjust the airflow meter? you can do this with an allen key.

oh by the way sorry i havent mailed the grille yet. i have been swamped at work, ill get it to you i promise

saabfan

no worries--i have tried but she becomes hard to start--at initial start up it seems to idle ok but as it warms she gets this very annoying idle search or loping --is there a special procedure for adjusting this mixture screw? any common vacuum leak areas? thanks again guys

saabfan

85cosworth i found some very helpful tips at mercedes-cosworth.co.uk i have not tried anything yet but plan to this weekend i also read something about the coolant temp sensor having an effect if anyone could help clear any of this up...thanks

PhilipM1

Please keep me posted in your finding.. ive been trying to find a way to make my car stop vibrating and hopefully what you do might help my car also. Thank you and good luck.

85Cosworth

I haven't had a chance to look at it lately. Spent the last couple weekends helping my buddy fix up his truck. Trying to fix all the leaks. Then spent this weekend putting on exhaust headers and electric fan to try and help my winter beast get better than 15mpg (a 95 full size Bronco with 351 V8). And now I have someone looking at my 16v this weekend to see if they want to buy it.

mctwin2kman

9 times out of 10 the cause of that fluctuation is a bad water temp sensor, the one used for the CIS-E system to know engine temp. Depending on engine and year it is either the two pin, separate connectors for each pin, or 4 pin sensor in the sensor array. Test the resistance at 80 degrees engine temp across the two pins on the two pin deal or across the opposing pins on the fours pin.

Below is the chart for what the readings should be.

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

saabfan

you know i did notice while sitting in traffic that the gauge on the dash was showing the car running hot but the additional gauge (part of the 16v pkg.) read normal (around 80c) is this possible? i did not hear the high speed fan running and shortly after while i was able to get air back accross the rad. and moving again she died out a few times never before or since has this happened--thanks again guys for the help i will check on the temp sensor tommarrow at work i will keep everyone posted on the findings

85Cosworth

The dash gauge reads water temperature and the gauge below the radio reads oil temperature. Mine usually read the same.

mctwin2kman

The Water Temp Sensor has nothing to do with gauges. Don't let the name fool you.

PhilipM1

what does it do then ?

mctwin2kman

It is one of several sensors that tells the CIS-E Fuel system what to do. It lets the controller know the engine temp to lean or en-richen the mixture for warm-up and normal engine operation. There is also an altitude sensor, O2, and air temp on certain model years. The CIS-E Controller then adjusts air flow and fuel mixture using the IACV and the EHA as well as the Ignition Control Module.

saabfan

is one of these sensors a better starting point than another? she idles between 800-1200 and normal driving never gets hot but if i sit the temp gauge rises i'm sure i might have multiple problems but the idle thing is driving me nuts --thanks for all the input guys