Adjusting erratic idle on 1898 VZ Legacy (EJ20D)

[rxleone]

Hey all.

 

Just wondering if anyone had any info on adjusting idle on a EFI EJ20D engine off a VZ Legacy 1898 (BC5)?

 

I had a timing belt snap in my engine. Bent valves Oh well, life goes on.

 

Anyways, instead of going to the hassle of ripping the heads of and reconditioning them, I just slapped a whole new engine in. Identical engine, but I'm having trouble with the air control valve, which is giving me a very odd idle. I replaced both that and the throttle position sensor from my old engine (which was a very good engine until that bloody t-belt gave up!) but I have no idea how to set them. I've heard the ACV controls the cold start idle, which the TPS is responsible for the hot idle. But every time I seem to get it idling right (which is about 750rpm by my ear) it runs fine, then seems to mess up.

 

It used to hunt for a good spot, and I seem to have cured that, but sometimes it'll idle nicely, then decide to idle when warm at 2000rpm, then drop again.

 

Now I don't think the car is worth the money of getting it professionally tuned, but I might have to seeing as I have no clue about how to get it idling right.

 

Does anyone have any expertise in this sort of area? I'm absolutely stumped when it comes to electronic fuel injection.

 

If you need any more info please don't hesitate to ask. I really need this old girl to run right!

 

Thanks for your help guys.

[Legacy777]

Did you end up figuring this out, or are you still looking for help?

 

Also, I'm assuming it's a 1988 Legacy, correct?

 

Is the TPS a 3-wire or 4-wire TPS?

 

Is the idle air control valve have 3 wires going to it or two?

 

 

If it's a 4-wire TPS, the only adjustment that needs to be made is with the idle switch.

http://www.main.experiencetherave.com/subaru_manual_scans/FSM_Scans/TPS_testing3.jpg