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Discussion Starter · #1 · (Edited)
So my mileage is 339k with 94k on engine.
Have been receiving CEL= P0420 catalytic code for 6mnths then it started running bad (almost like a mini episode but not the full on end result of this post) which I had a misfire cylinder 1 code, replaced ignition coil, wires and plugs, not getting any codes still same @temperature rough idle/stalling, so I replaced crankshaft and camshaft sensors just in case, still the same after 30mins rough idle and then stalling with no CEL.
Also #1/2 spark plugs were shot so I definitely was running limp mode with a 0420 showing for at least 6 months.
Runs super smooth now until the 30mins then it misses or hiccups one time and runs good then again and at the same time my rpms drop and goes back up, normally dies esp when in gear so it's parked for now.

Asked a mechanic who said IACV idle air control valve, which I'm not sure but I think it's built in to the throttle body, also might be chasing gremlins for it was running great AC and everything couldn't get the problem until I rolled up 2 Windows same time and then it started again, that only happened one time, but the windows have always kinda seemed slow and now faster and everything is running better that's for sure.
Any insight or ideas much appreciated
All parts or at least most are original, except for the crucial engine swap stuff as needed.
Thanks
 

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Discussion Starter · #3 · (Edited)
Yes my mechanic said it could be a grounding issue after I explained the windows, I'm gonna check everything now, yeah my mechanic also said about the IACV said it could be built inside the throttle body.
Awesome hopefully this will get it :)
Thanks again
 

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Discussion Starter · #4 · (Edited)
Yeah after going threw the top ones and I'm doing the bottom ones I'm not seeing anything bad, I actually did one I thought looked bad and it wasn't, most of the main ones have good sealing on them not saying one of the bottom ones isn't ate up from the magnesium chloride just not finding it yet, so just in case I ordered the reman cardone 67-2105 still looking for GROUNDS :)
Thanks again

I might've found something the two ground straps, maybe it's something it seems like it takes longer also when it hiccups maybe they are spread out more, I'll look for more GROUNDS
 

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I've never replaced a throttle body assembly on a Subaru. I clean them and they work smoother after.

Insulation being in tact doesn't mean anything. The cables need to be checked with a multimeter set in ohms end to end. You want 0.0 ohm between the negative post and the end of the main ground. No more than 0.1 between the negative post and the alternator case.

The bundled ground on top of the passenger side of the engine is for the engine harness. That one needs to be clean and tight. Don't break the bolt.
 

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Discussion Starter · #6 · (Edited)
First of I totally agree about taking the throttle body off and cleaning it with throttle body cleaner and a nylon brush, it worked 3 times before and I didn't know about the relearn process so it taxed the throttle body until it worked it out.

Second my mom had the car before me and had the head gasket issue for years and now I've got the pressure sensors leaking both sides almost like misting everything with oil, so it seems my wires have been lubed or I should say caked on them.

Yeah I've never replaced one, just throttle body positioning sensors on other vehicles and I just learned about the IACV idle air control valve which I've seen a you tube video Subaru WRX I think he had with the same issue for which he cleaned it and it fixed the issue,, same issue or at least it seemed like it.

In my opinion the no CEL or a part that just doesn't scream I'm bad is the worst esp with 339k on all my parts esp to a computer tech therefore I rely on mechanics knowledge for you all have been doing it for years.

Oh I'm not saying it's a fix all and I'm still looking for GROUNDS and I'll clean the plugs :)
Thanks a bunch

So I thought maybe I should show you some of my harness and what I'm seeing.
My straps after cleaning them :)
Also I'll get my buddy to do the voltage testing I'm a total rookie at those things and just decided long ago I didn't like em, it's definitely user error :p,,, I'll go and buy one and force myself to learn it. :)
 

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Discussion Starter · #7 ·
So I didn't get to the tester but the new part came in and like a kid in a candy store I installed it and everything was smooth as butter until it happened and then something new happened it started to rev up and I gave it a bump of gas and still going up so I shut down and this time I had a CEL P0638.

I'm gonna check everything, I wonder if this is what my old one was supposed to do or say?

If I find nothing I'm just gonna get it towed, I'll use the tester in the morning.

Whatcha think?
Thanks again
 

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Discussion Starter · #9 ·
Yeah that's why I replaced them with iridium denso plugs and denso 7mm wires, I guess those NGK plugs didn't last 4 years 94k miles :)
I've been searching wires and connectors, I wonder if it's my PCM or pedal messing up?

Thanks all
 
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