Adjusting 348 Idle Instructions

I am going to try to adjust my idle tomorrow and have all the tools ready. Can someone please explain to me what the "Idle Air Speed Motors" and the "Intake Compensation Soleniod Valve" are. I think I have the rest figured out but cannot for the life of me get that part. Thank you.

INSTRUCTIONS AS PER "MY348.com":

1. IDLE Adjustment, part 1: Connect a large U-tube mercury manometer (see picture above) to the intake plenum, one port on the 1-4 bank, one on the 5-8 (don't bother with vacuum gauges, doesn't work at all).

2. Disconnect the idle air speed motors electrical connector and block their ports into each plenum (see tips above).

3. Disconnect the Intake Compensation Solenoid Valve**.


4. Balance the airflow relative to each bank by adjusting the brass colored screw on each throttle body.

5. Do not touch the butterfly stop screws, the throttle bodies are factory set.

6. Monitor idle speed, should adjust to about 1000 rpm, adjust with airflow bleed, not butterfly.

7. Ensure that the exhaust is not blocked by a bad catalyst.

8. Measure exhaust gas content for additional clues.

9. Reset ECU's by disconnecting battery for about 10 seconds and allow them to "relearn".

 

This process seems like overkill. Is disconnecting and plugging all these parts needed. Why cant you just hook up a vacuum line to each intake plenum and then adjust the idle screws to the desired RPM while making sure each plenum is drawing equal vaccuum?

What is the difference between a mercury manometer and a updated set of vacuum guages? They essentially do the same thing. These manometers were common is balancing carbs on older motorcycles but these mechanics dont even use these anymore.

Am I missing something or are the instructions overkill and 20 years old?

I am simply trying to level out the warm idle to 1000K. Right now my car is idling at 1200 when warm.

HELP!!!!! LOL!!!!

 

What center screw are you reffering too?

 

That is correct. That screw does just that and if you play with it and do not realize this, it will make a mess of the way the car runs until you realise you have totally "unsynced" both sides of the engine. Trust me I know....I did just that.

I followed the idle adjustment procedure listed on www.my348.com. I used a very high dollar set of vaccuum guages and in the end, it worked perfectly. The warm surging idle went from around 1200 to a steady 950-1000 right on the button. I was able to ensure that both sides were even and by doing so the idle is buttery smooth.

So, if anyone has a slightly high idle issue, this process works and should, barring any other issues, correct the problem.

Thanks and hopefully this will help somebody down the road.