I agree. I was refering to the post where he removed the ICV and started the engine and did not understand why it ran worse.

many thanks gents -- i have a few things to add---

-first, in the design of the idle valve it appears to me that there is a constant bypass (a small tube say about eighth inch in dia) that "short ciruits" air flow around the valve.
-second, I was absolutely astounded that the idle didnt rise when power way removed and now I think I understand that element.

another question -- in start up does the EHA determine fuel flow or is that determined by mechanical means until the lambda kicks in??

I will try the idea of taking the valve out of the equation and see what impact that has on idle.

Thanks much.

The EHA does play a part, The "key on engine off" eha current is 75ma, (the engine is very hart to start without it) once engine starts it goes down. My engine takes about a minute to reach closed loop with eha current centered near 0ma.

Well I just tested the eha current. Cold start (KOEO) condition I observe zero current to the EHA. During starting cranking no current either. After warm up I observe a current to the EHA of 4-5 ma --- it moves arounds a bit but pretty constant.

If I restart the engine when warm --- the EHA current is about 100ma and the car starts right up.

So mebbe I have learned something. But now I wonder what determines current flow to the EHA during cold starts that could be contributing to the problem???Also, should be current eventually go to zero at idle condition???

Jeff is right you should have 75ma on a 4.2 and 5.6 116/117 v8s, key on engine off.

Maybe the same reason you aren't getting proper idle current is the same as why you can't get 75ma. Its a lot easier to do 3ma than 75ma or 600ma.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I don't know how cis-e control works, but I can tell you what I have observed on my car 87 560sel.
The KOEO is allways 75ma. While trying to solve a hard starting problem I noticed while cranking the current dropped to 0. The position pot should read .7 volts at idle between pin 1 & 2. Mine was erratic. Replacing the pot stopped the current from going to 0 , but did not solve hard start problem.
Check the on/off ratio %. If it is a fixed value the value is an error code, and will indicate what component to test.

Thanks Jeff-
Well based on my testing i am concluding now that the ECU is not sending EHA current during start up/KOEO/ I put the meter on the EHA and watched the current. At cold start, there is no current (or very little I dont remember) --- if I start the car and let it run for a bit and restart it ---- voila-- EHA current (about 100ma) is present and the car starts right up idles faster for a bit and then slows to normal idle.

So now the querstion is -- what are the signals that the ECU uses on start up to provide enrichment thru the EHA???I have the manual but it isnt clear to me which signals need to be present.

I would like to check the idle position pot but can u tell me where it is on the engine???Is if near the throttle switch???

Thanks.

The pot is right side of air meter box . (opposite eha ) It has a 3 pin plug, pull it out far enough to get the test leads on. I'm writing this from memory could be wrong. Put the car in KOEO put leads on Pin 1 and 2 . Voltage should be near 0. Deflect meter plate, at idle position the voltage should be .7volt as you push plate down voltage will go steadily up. I think voltage between 1 and 3 is around 5 volts.

I also did this test while monitoring eha current and discovered the current went to 0 when I deflected the plate to idle position.

There is a lot of good info on position pot in fouum.