No vacuum leaks, been over everything with a spray can.

'89 doenst have codes. I think it was the last one not to.

Work currently aborted due to rain

''reconsider the water sensor and the resistor you installed'' reconsider what? It stopped the 1200+ rpm idle at ~80c

FWIW, the pot adjustment was made by sliding the full assembly up / down from the far right.
What does the itty bitty adjustment towards the center actually adjust ?

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

My car has a similar idle problem and the fault codes and these are what I had initially:

"7 TNA (Engine RPM) Signal
14 Road Speed Signal At CIS-E Control Unit
18 Current To Idle Speed Air Valve
27 Data Exchange Fault Between CIS-E Control Unit and EZL ignition Control Unit"

Cleared the codes and the only one that still comes up is 14. From what I have read, most common issue is the failure of the hall effect sensor that is on the back of the speedometer. Other potential issue is the CIS computer itself.

I have a likely good used one that is waiting to be installed just haven't been able to do that in the past 4 months. My issue really isn't that bad atm.

Part number is 0075422917, should be about $55 at the dealer.

__________________
Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

89 seems to be a production break point.
Your 93 electronics are different than mine but thanks

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

I believe the inside diameter of the mechanical valve is 1/2". The IAC is Normally Open unpowered, so that's why your idle is high. Try the gate valve idea, less than $10.

__________________
1988 300E

Potentiomiter may be the problem ,remove it and check out the carbon track if worn its shot.

Attached Thumbnails

 

If you unplug your air idle control valve the revs should be about 1200 to 1500 rpm - do you still get that after your resistor modification?

As for the little adjustment thing in the centre of the potentiometer that's the fine tuning. "Everyone" says don't touch it.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

He's already done that I think

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

If you don't have the ability to measure fault "blips" then I believe the fault codes are given in terms of on off ratio aren't they?

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Potentiometer is brand new, no change

I dont know bout the fault codes

tilac, sure cant hurt

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

Tnbob Take the vacuum pipe of the brake servo and check vacuum with a guage .And if it fluctuates with it off the problem is on the engine side. Blockthe pipe with a bung then If it is stable your brake servo is leaking vacuum.

opti... thats one I actually havent tried yet.

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

tnbob let us know please how you get on with it .

rain, wind and coool postponed work

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

for new readers/problem solvers, here is a recap
New cap and rotor
New fuel distributor
new EHA, torx's replaced with flat head screws
new pot on front of FD
NEW vacuum hoses to and from the IAC, one to the block is a real (&^*(&^*
IAC replaced with used one, both tested good.
OVP relay replaced, no change
New injector boots
New temp sensor with resistor mod.
The temp sensor stopped the high (1200ish rpm) idle

Vacuum leak checked with carb cleaner spray. NONE found

Things to do:
Confirm alternator voltage regulator is working properly
Change fuel pump relay with new one.
Replace IAC with gate or ball valve setup
Start a mold for some type of as of yet unknown shaped charge

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

I did find a nice pictorial of how/what/who the IAC is supposed to do.

http://www.k-jet.org/img/articles/diagrams/cis_system1.jpg

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."