Here I am, replacing all fuel injectors on my 95 E320 W124 104.992 California, because I am still chasing idle and performance problems after the PO drove it into the ground with bad ECO wiring.
What do I get now?
Suddenly, I have an elevated idle at about 1300 RPM's in Neutral and about 900 RPM in Drive.
First thought, I get un-metered air. Nope, I checked for leaks around the areas I worked on.
Acceleration from mid range does exist in its modest form. Always had been this way. I am not driving that fast any-more, anyway.
Using kick-down helps a little, but I have to get off the accelerator a bit. Been doing this ever since the replacement TA.

Replaced parts so far:
New Spark Plugs
Replacement throttle actuator
Updated wiring harness
New Ignition coils
Replaced almost all vacuum lines
New OVP
Replaced e-gas computer (was damaged by old Throttle Actuator)
Cleaned out EGR pipe
New fuel rail pressure regulator
New fuel filter
New Oxygen sensor
Another purge valve
New Cam positioning sensor
and probably more, just can't remember any-more.

The hard code I am reading is 6
"Idle speed control incorrect, fault from EA/CC/ISC"
Duh, I know that much, since my idle is high.
No other codes.

I am stunned!
Tried to reset ECU, but that doesn't happen because of the existing code, I believe.

The only thing I can think of, is to disconnect the battery and try to reset after reconnecting, don't believe it will change a thing.

What can go wrong, by simply replacing the fuel injectors?
Nothing is leaking!
Nothing is sucking air in where it shouldn't!
Why is the idle suddenly 300 RPM's higher than before?
Wrong injector? They claim it is for my model.

I had codes saying that the "Throttle valve potentiometer actual value too low." before.
However, I dismissed those codes, since they seemed to appear at random.
Is it possible that the ECU has taken a hit too from the old broken (wiring) Throttle Actuator?
Random codes, CAN bus errors, one would think!
Is my replacement TA faulty, sending the wrong signals?
Too many questions, no answers, can be real frustrating....

If this keeps on going, I could have bought a new one, ha, ha...

__________________
Mostly, I don't know notin, I just know where to look.
I am looking back, to over 30 years in Electronics Design.
Electrons don't care if they move in a car, computer or relay!

95 W124 E320 M104.992 - Because, I love to repair, naaaah!
Over 221,000 Miles
Cheers,
Norbert

I have an m103 which is different. But when I was getting that code I replaced my IAC with a brand new Bosch one and it fixed it right up. I didn't see that in your list of repairs.

Also should mention I replaced the mechanical MAF sensor around the same time. I assume on the m104 it is a more typical electronic MAF sensor but it serves the same purpose. I had a 2000 4.6l Ford engine that needed that cleaned. On the m103 it was an actual potentiometer doohickey.

Hi tnx for your input.
Yep, the MAF on the 104.992 is electronic and was replaced, with a new genuine Bosch about 300 miles ago.
I am not too familiar with acronyms, also most everyone uses slightly different ones.
By IAC do you mean Intake Air Control ( Throttle Actuator )?

If it is the TA, then I replaced mine shortly after I bought the car and I discovered bare wires hanging out from it, shorting everything there was. Aside, it wasn't drivable anyway!
Also, I replaced the e-gas computer (foot compartment, passenger) since it had a damaged input (guess idle contact switch input) and idle was running even higher then now.
The TA has two rheostats mechanically coupled to the air flap. The signal produced, will give the flap position to the ECU ( I believe). One of them is for normal driving and the second one, I believe is used to calculate a delta for the Cruise Control.

It could still be that the TA isn't functioning correctly, since it was a used one, but with good wiring. I only measured top and bottom resistance, before installation. So it could have jumps. I should take a complete resistance curve from it, then I would know.

I should mention that the Crank Case Ventilation is routed through two short rubber hoses and attached to the intake manifold, don't think it is part of the intake at this place. But it routes to the main air intake manifold. The hose connector are some PVC (Plastic intake manifold) and can't handle the temperature changes very well. So it simply cracks and if you look at it, falls off. I needed both to replace, since they were hard as a night stick. The PO did some repairing at the smaller one of the two hoses, but was broken off. So they opted to squeeze a tube of RTV onto it.

I kind of repaired it, using a short piece of brass tube, but has now a much larger inside diameter. I have a hard time to believe that this change would make such a difference in idle. On the other hand, anything after 1980 has become so sensitive and minor changes may have a real big effect.

In any case,
Thank you!
I'll have to check a few more things, cause I can't see why the gas computer would go out of business just by replacing the injectors.

__________________
Mostly, I don't know notin, I just know where to look.
I am looking back, to over 30 years in Electronics Design.
Electrons don't care if they move in a car, computer or relay!

95 W124 E320 M104.992 - Because, I love to repair, naaaah!
Over 221,000 Miles
Cheers,
Norbert

I looked your car up and was surprised it doesn't have a IAC. Prior to my m103 I worked on newer (2000 and a 2003) Fords which do have an IAC. I looked the price up and found out why you go a used ETA! I found this page which has how to bench test it at the bottom of the page. Mercedes throttle body rewire

Yeah, those are expensive!
A new one from the stealership is running anywhere between $1600 and even $2000. At this price, out of the question. Between the two of us, ha, ha, I paid only $1000 for the car.
The rebuilt ones are about 50% of a new one.
And Victor, does charge about $300 for a rewire, but I don't like the looks of the wiring.
Also, the bench test he does, is in general a measurement of resistance on both ends of the rheostat. They are fairly large and I believe made of a carbon trace and slider.
In theory, if a vehicle is driven mostly in stop and go traffic (throttle is going between idle and some other position, constantly moving), the thin carbon layer could wear faster off in that range, causing false values.
They used to do that in the earlier cars with the potentiometer attached to the butterfly. This was a one way solution and most likely done without a computer, simply send a voltage to an OPAMP which in return controlled the fuel injector (indirect injection) looked like a carburetor.
Because of the high price, I went with junk yard model at $125 much more down my alley, ha. But I don't have any history of this Throttle control device.
I bet, I could find a new rheostat, if I search long enough through the internet.
These rebuilds have to get new ones, otherwise it would be a gamble.

Aside, I am almost convinced, I screwed up with the oil vent hose adapter repair.
The broken piece had only about a 1mm dia. hole, where fumes could restricted pass through. I had to drill it a little, to fit the brass tube that I inserted. That hole is now about 7mm and attached to the intake manifold via a 1 1/2 inch long rubber hose. There is no restriction in flow anymore, its like not having that hose attached to intake at all, allowing un-metered air to enter the intake manifold.
Been lazy this weekend, otherwise I already would have checked my theory.
Will check tomorrow and post the success or failure.

__________________
Mostly, I don't know notin, I just know where to look.
I am looking back, to over 30 years in Electronics Design.
Electrons don't care if they move in a car, computer or relay!

95 W124 E320 M104.992 - Because, I love to repair, naaaah!
Over 221,000 Miles
Cheers,
Norbert