1999 Subaru Legacy 2.2 motor in a 1984 VW Vanagon. Struggling with a couple idle issues. No Check engine codes.

The first is some hunting/surging on warm up. The second is after engine reaches operating temp it idles at normal rpms (750-ish) until it goes above ~1600 rpms on acceleration. After which motor hangs at ~1600 for idle. I can get idle back down to normal if I lug motor below 1300 or so rpms then it will drop back to “normal” idle. On next blip of throttle though above 1600 rpms it is back to hanging. If I restart car idle returns to normal until acceleration gets above ~1600 again.

I have smoke tested engine. TPS voltage at idle is 0.48 volts warm or cold. Plenty of slack in throttle cable. Changed out MAF for OEM. New OEM ECT sensor. Cleaned throttle body assembly and tried new IAC valve. Cleaned injectors and changed out O-rings. Newer O2 sensors, plugs, and coils. Also have a spare ECU which shows same issues

Any suggestions on what or where I should check next. Open to anything at this point.

 

 

Edited March 19, 20224 yr by Willrb

Have you checked the TPS under other throttle positions to see if it functions like it should "off-idle"? I assume you've checked the TPS voltage when the idle is normal vs. when the idle is high to compare?

I'm not sure about the phase II EJ22, but I know on mine the IAC is adjustable, is it possible yours needs adjusting? I'm no expert but those are the two things that I'd check first.
Maybe someone with more experience will have some more specific ideas.

Edited March 19, 20224 yr by laegion

Thanks for the reply.

Did check TPS at various different positions and seemed to be functioning correctly. Also checked at normal and high idle. No change in TPS voltage or throttle body angle % between the two.

I don’t see an obvious way to adjust IAC, but am also no expert.

 

Throw away the stock computer and put a LINK ecu on it. You can get rid of the MAF and not have to worry about all the sensors and interlocks that you are missing. 

GD

Recently my throttle angle % at idle has been showing 2% versus zero. How do I got about adjusting this to get it back to zero at idle, does it go with TPS? My TPS is adjusted to 0.5. Thanks.

You install a LINK ECU and click on TPS calibrate. 

That stock computer is just a huge waste of time and effort. 

GD