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Idle inconsistent 900

Hi Dave,

I just read your latest post and as usual you are more detailed than I am.

I have six cars. One is a K jet mechanical with auxiliary air valve for warm ups. A heating element changes the idle speed so it in general mimics the warming up of the engine. It is actually very effective if you get the spring tension set correctly from the outside adjustment.
We have come a longs ways from that mechanical injection system but my gosh I have had less trouble with just by keeping fresh gasoline in its veins.

The other cars started in 1984 LH 2.0 for me. The IAC has three pins to move the vane in each direction.
This went on to my 1986 on with three pins but it is a LH 2.2 doing the same thing.
My next cars are 1991, 1992 and 1993. LH 2.4 with some cars getting LH 3.0 with some having a variable resistance throttle switch. I do not have one of those.

I do not know when, from 1986 or the eighties forward, when the IACs changed to the two pins.
I assume that the change over came with ECU improvements somewhere around the 1988-89 EZK-16 and CPS away from distributors with Hall effect sensors.
The ICUs on those were in the engine bay.

The solid or positive return spring IACs was a safety refinement. IMHO
I have not had any problems with excessive idles with the three pin models but I can realize a possible failure. A DIRTY or worn IAC can still raise its ugly head.

I clean both the way you suggest. The three pins you can twist violently to check for a clunk.
On the two or three pin I used a 9 volt alkaline battery to simulate the drop in system voltage during cranking.
I use thin leads going into the connector. Things are narrow in there.
I listen for a nice snap on both types. You want it both ways even on the three pins.
Moving the lead around during pin swaps gets that result.
Plus the battery is a lot lighter to use on a bench ๐Ÿ˜Š
The lesser current available, in my mind, simulates the ECUs power capability because they are transistors after all and have limited power circuits.


Now I think I have my LH series in order of production correct with my ownerships.
You do a lot of excellent writing and if itโ€™s an error you are definitely allowed it!
Itโ€™s hard to get as much as you put down in writing and not have it absolutely correct or we as the readers reading or interpreting it wrong!

My chronological order I have missed some years along the way.
This is not say that the rest of the world get changes sooner or later during productions besides to different countries and sold later in life.

I really appreciate your posts with any clarifications and trust me, I read this one a couple time before I said anything.

Between our two analogies I think he should have a good picture of what he is dealing with.

I too need to hear about the results.
๐Ÿ‘€ it being written is our only hope to know our efforts worked!

Excuse my mistakes please.๐Ÿคซ

Phil






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