Going to try to give as much detail as possible here.

Car is a Turbo 2000 Honda Civic SI

Running eCtune map that has been treating me just fine for the last year

Car was recently in the shop for a headgasket. Battery died while sitting and had a cell in the batter go bad.

Problem:

Car runs great and starts right up and doesn't overheat. However once it reaches operating temperature whenever I press in the clutch to come to a stop when the RPMs drop they don't catch at the idle speed where they should. Instead it will drop to 500 or less and 8 times out of 10 it will cut off. Even if it manages to stay alive there is obvious surge, but not your typical honda surge this is from 600-850 rpms. The car sounds like it is struggling to stay alive. The problem is for sure in the RPM drop because when I shift out of gear early and use the throttle to gradually take the RPMs down instead of letting them just drop I can keep it from cutting off usually.

So any ideas?

 

First try cleaning the IACV and bleeding the cooling system. Any CEL codes?

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The bleeding procedure may take 20-30 minutes:

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push the dash heater lever/**** to MAX heat.

3) Follow the directions in the diagram below

 

It has already been bled. I haven't checked the IACV yet I just hate dealing with it being so cramped back there. Will check that today. No CELs. Just curious, but why would a air bubble in the cooling system affect this?

 

Idle speed is in part controlled by the coolant temp signal sent to the ECU from the 2-wire ECT sensor under the distributor. Air trapped in the cooling system can cause the ECT sensor to sense and send variable erroneous temp signals to the ECU, causing a fluctuating idle.

You might want to bleed the system again as detailed in my earlier post.

Does the CEL work?

 

Wow great information. I didn't know that. I will bleed again today. Thanks for your help. Yeah CEL works.

 

wht was the problem? im having the same issue