Been troubleshooting this with a few friends but unsure of how/why this is happening.

I've had idle issues for a while and the car just used to idle super high. Now with the head refreshed I've gone through and sealed everything.

Had an issue with the car trying to cut out when I put the clutch in over 3k rpm so I tried going through the idle valve duty cycle and it's doing jack. No changes to idle with plugging and unplugging the valve. Checking voltage at the valve led to zilch so now I have to chase it back to the ecu.

Any recs on how to proceed from here? This used to work so I'm not sure why it decided to cut out. Any suggestions?

 

Ecu sends a ground, not voltage. Voltage just comes from a splice off the main relay. Powers injectors, cam/crank/coils too.

 

I disagree. Pin 3O from the ecu supplies 12V for the IACV.

 

NA is just 12v from the main relay. It's still gonna provide a ground for control - from the ECU it's probably got a common voltage rail with a reverse bias'd diode for inductive flyback suppression.

 

Going to go check voltage at the harness next but what should I do if that doesn't work?

Can I just grab 12V from the egr or something? It's not being used.

I do have voltage at the TPS since that's working and it comes off the same part of the harness as the iacv.

Car is running okay other than this and its gonna be nuts trying to drive a car 250 miles for a move if it can't idle at all. That and breaking in the clutch has been very exciting lol.

 

TPS gets 5v. IACV gets 12v. They have nothing in common.

I already mentioned in your build thread why you shouldn't just use the 12v source for the EGR without further testing. I also told you what tests to do.