Hunting idle ej22

[bbrow632]

Hi everyone,

I have an idle issue that I can’t figure out. I’ve swapped an engine from a 98’ legacy ej22 auto into an vanagon. 

when I installed the engine I started for a couple minutes without coolant in it to see if it idled. It will idle fine without coolant. Once coolant is added to the system it will hunt. 

what I’ve done to try and resolve the issue:

new IACV, new TPS, cleaned EGR, 3 different ecms, had mick at BUSARU go over my harness ( it is good), checked for leaks. 
 

there are no consistent codes. I am getting a knock sensor fault code intermittently, I’ve taken it out and checked for cracks and it looks fine. 
if I unplug the TPS the hunting goes away but will idle at 1400rpm. The moment it’s reconnected or the internal switch touches the bar in the the throttle body it will drop to 850rpm and begin to hunt. 
 

I’m at a loss with this issue. I need some help. Has anyone had something like this?

Edited July 9, 2023 by bbrow632

[el_freddo]

I had something similar and these were (from memory) the things I swapped out:

- cleaned TPS 
- new coolant temp sensor 
- new knock sensor 

I don’t know which one was the issue. I’d be looking at the coolant temp sensor and TPS closely. I’d say if you don’t know the history of the coolant temp sensor, get a new one fitted. 

This is the video I did back then, while a bit different to what you describe, I reckon it’s related. Mine is a Gen1 EJ22E in an L series with a cut down wiring loom like what you’ve done in the vanagan. 
 

Cheers 

Bennie

[bbrow632]

Update.

I replaced the knock sensor, coolant sensor and swapped out the TPS with two different ones without it making a change to the hunting. I timed it today and it idled at 850 for 2mins, 34sec before hunting. The engine temp was around 122F.  I thought it could be an issue with the IACV and the coolant so I by passed the coolant hoses to the IACV, no change. The only thing that makes it stop is unplugging the TPS. 

[lmdew]

Have you cleaned the intake?

Seafoam works well.

[Steptoe's photos]

I can't see the coolant hoses being blocked off would change the air flowing through the valve.. What I would do here would be to dismantle the IACV if you can, and if has a gasket with holes for transfer ports, make a new gasket that covers all ports up, so no air transfer at all. I think I still have my full gasket on my EJ20 from diagnostic tinkering sessions. I found the original o ring cross sectional shaped gasket was too big to fit back in their recess grooves !!