Help me fix my 3fe equipped 1991s crappy idle! (Please)

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Nothing in there about the big o ring, you can see it in the pics though it does look to be the same size roughly. Maybe ill find a part # for that one. funny how toyota made the isc valve so much higher quality on the 1fz, with the nice metal plate and all. mines all plastic and the mating surface flatness and integrity is pretty questionable lol
 
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Time for an update. I fixed the truthfully very minor vacuum leaks that were coming from the pushrod cover and the idle speed control valve. A little bit of rtv on the o ring and a dab of jb weld on a crack in the body of the valve ultimatley took care of that, the pushrod cover is kind of a bigger more tedious job even though it's just a 3fe, but I pulled the cover off, hammered it nice and straight, flattened the fastener areas with a punch and installed a brand new oem gasket, no more smoke coming from behind the dizzy when smoke testing. I even found a vac hose that was barely letting smoke out, I replaced it and now it has a nice tight seal and doesn't allow smoke to come out even with the pressure cranked all the way up on the tester.

None of this has fixed my rough idle/stunble. I now have a very low idle which the ecu will eventually correct im sure indicating that there is less air coming in, a good sign, but it still has a random stumble! He'll it almost seems worse!

All of this is starting to remind me of lelandEOD's situation where he could never get his 3fe to run right so he gave up and swapped a 1hz. I fear I'm just gonna have to do the same thing :(

Time to do all the factory service manual pinpoint tests (again), at this point it has to be electrical right? Ive been through everything mechanical. The valve clearance, compression, Fuel pressure, timing are all fine.
 
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I now have a very low idle
I would pull the 15 amp EFI fuse in the fuseblock on the left fender for a few minutes. This will reset the ECU and force it to "relearn" all the sensors. It will also clear out any old error codes that have been stored.
I do this anytime I change anything under the hood.
The idle should be slightly higher than normal for 1 or 2 drive cycles after a reset and settle in at 650 at normal operating temp if everything is happy.
 
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have you tested via the FSM the AFM and water temp sensor? Easy tests to do to confirm these guys are within working order. Have fuel filter and fuel sock been replaced? Cheap replacements for possible issue but also maintenance items nonetheless.
 
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have you tested via the FSM the AFM and water temp sensor? Easy tests to do to confirm these guys are within working order. Have fuel filter and fuel sock been replaced? Cheap replacements for possible issue but also maintenance items nonetheless.
Yes I have done both of those and they both tested ok. But there's no harm in testing again. Another thing I'd like to do is do these tests on the ecu side so I can test the wiring, rather than just testing the devices themselves
 
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I would pull the 15 amp EFI fuse in the fuseblock on the left fender for a few minutes. This will reset the ECU and force it to "relearn" all the sensors. It will also clear out any old error codes that have been stored.
I do this anytime I change anything under the hood.
The idle should be slightly higher than normal for 1 or 2 drive cycles after a reset and settle in at 650 at normal operating temp if everything is happy.
I'm going to try this again, I did pull once of the battery cables but maybe it wasn't long enough, I was eager to see how it'd run
 
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I'm going to try this again, I did pull once of the battery cables but maybe it wasn't long enough, I was eager to see how it'd run
Pulling a battery cable or pulling the fuse accomplishes the same thing. I prefer the fuse as it's quick and easy. 5 or 10 minutes usually does the trick, but I just pull it before beginning any work.

You should also listen for the ISC valve to reset itself on engine shutdown. You should hear 3 or 4 "clicks" from the ISC as the ECU resets the stepper motor. This is mentioned in the FSM and is specific to the 3FE.
 
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Final update. Hopefully lmao.

So next step was a conpression test. This would rule out a. Me botching the last valve adjustment, or b. Some kind of internal engine damage that may have occurred from the engine detonating like a broken piston ringland. I was suprised I actually had some pretty great numbers.

Now even though the plugs had recently been changed, they were already ruined and ashy with deposits all over. Here's a pic of the worst one.

So basically it just needed plugs. Replaced with ngk vpower bpr5ey-11 and set the ignition timing to about 8 or 9 degrees with a timing light and now it runs great, it idles right where it should at 650 and no more pinging when the engine gets hot on woody trails. Runs great on 87 octane just like it should.

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Also finding this repair manual was very helpful to keep me level headed. it is nice to just see what Mr T says to do and go step by step. It's for 1988 but not much changed between then and 91 as far as the 3fe.

 

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