Rough idle - my fault, but I don't know what I did (2 Viewers)
- Thread starter CharlieS
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Faulty 1FZ-FE Idle Speed Control Valve / IAC
Hi everyone, This is an extension of my post for baselining our FZJ80: Baselining our first 80 series: A '93 '3x locked FZJ80 - https://forum.ih8mud.com/threads/baselining-our-first-80-series-a-93-3x-locked-fzj80.1301624/page-4 I was hoping to get more eyes on it. I've been suffering from a...
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CharlieS
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- #44
Thank you.
Faulty 1FZ-FE Idle Speed Control Valve / IAC
Hi everyone, This is an extension of my post for baselining our FZJ80: Baselining our first 80 series: A '93 '3x locked FZJ80 - https://forum.ih8mud.com/threads/baselining-our-first-80-series-a-93-3x-locked-fzj80.1301624/page-4 I was hoping to get more eyes on it. I've been suffering from a...
@Malleus posted good stuff. I found this specific post very helpful: Faulty 1FZ-FE Idle Speed Control Valve / IAC - https://forum.ih8mud.com/threads/faulty-1fz-fe-idle-speed-control-valve-iac.1305814/post-14886535
Guess I just need to give it a steady pull? Yes, that worked (actually gently pried with a screwdriver).
I think a tiny bit of corrosion on the metal collar was preventing movement of the magnet.
Let's see if I can clean it up and save it?...
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ppc
M Go Blue
How many times did you go through that sequence?
Each time running that sequence there is going to very little movement most likely not perceivable but if you hold on to the IAC you will feel the torque.
CharlieS
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- #47
It is reasembled and the plunger moves now. Not a lot, but it moves.
s1-s3 has 44 ohms of resistance though, and it should be 10-30. b2-s2 is 22 and b2-s4 is 22 ohms. Something still isn't right.
Anyone know what part of the assembly between pins s1 and s3 creates the resistance and if there is anything I can do to reduce it back to spec? Or am I looking at a new (and rather $$$) part?
Anyone have a usable IAC valve laying around that they'd hook me up with?
s1-s3 has 44 ohms of resistance though, and it should be 10-30. b2-s2 is 22 and b2-s4 is 22 ohms. Something still isn't right.
Anyone know what part of the assembly between pins s1 and s3 creates the resistance and if there is anything I can do to reduce it back to spec? Or am I looking at a new (and rather $$$) part?
Anyone have a usable IAC valve laying around that they'd hook me up with?
Last edited:
CharlieS
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- #49
The test procedure from the 94 fsm gave me that high resistance reading.
I found this other guide in another 'mud post, that tests resistance across a different set of pins. My IAC passes these tests with about 22.1 ohms across all tests:
b1-s1
b1-s3
b2-s2
b2-s4
Since the plunger moves, I'm going to look for an o-ring in the morning and reinstall it for now. I've done my best to set what seems like a reasonable depth, hoping it works.
The o-ring was super flat/ squareish cross section and hardened. I could have a vacuum leak here. Another 'mudder solved his low and erratic idle by replacing the IAC o-ring.
I might get lucky?
I found this other guide in another 'mud post, that tests resistance across a different set of pins. My IAC passes these tests with about 22.1 ohms across all tests:
b1-s1
b1-s3
b2-s2
b2-s4
Since the plunger moves, I'm going to look for an o-ring in the morning and reinstall it for now. I've done my best to set what seems like a reasonable depth, hoping it works.
The o-ring was super flat/ squareish cross section and hardened. I could have a vacuum leak here. Another 'mudder solved his low and erratic idle by replacing the IAC o-ring.
I might get lucky?
Malleus
Far west of Siegen
That was the problem with mine. A little polishing with crocus cloth and it was good as new. The throw isn't long, but it is enough to see. Maybe 1/8"? The action is created by the windings; if they're corroded there will be fewer of them and hence higher resistance.
@slow95z told me he had one when I did mine; I didn't need it so maybe he can help? I'd try a used one before I bought new; that's a lot of beer money.
CharlieS
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- Thread starter
- #51
Thank you!
I *think* the IAC is salvaged for now. Maybe I just hope it is...? I followed your lead and cleaned it up with some fine abrasive, gave the bearings a minuscule shot of teflon lubricant, and it is moving again (albeit not very far). Dunno, seems to do more than it did before.
I used a hardware store plumbing o-ring that is probably not the right thing, but it was what I could get quickly. It fit the groove and should hold vacuum. I can always replace it with a proper part later. Maybe.
Also, I was able to remove the IAC from the intake without removing the intake. I used some very long, thin screwdrivers that have "diamonds" embedded in the tip. Bought them at Sears years ago on a whim, but they actually come in handy sometimes - like this. The tips are ever so slightly abrasive and grippy. The screws didn't cam out and came out nicely. I did give them a rap with a ball peen hammer and a tiny dribble of Kroil (liquid, not spray) on the mating surface where the screw met the sensor. No drama.
My Dorman vacuum caps are pure shyte and leak like sieves. I pulled many off, and looped the one that I could, used a length of fuel line (new, cutoff length from a diff breather project on the 200) with fuel injection hose clamps to loop two larger ones on the intake/plenum. I put a huddexpo bb in the one small cap that I couldn't loop.
I popped the plug covers and made sure I was getting good connection at both ends of the leads. Everything looked fine.
I added a new (temporary) 4 ga ground wire to the intake, and it didn't seem to change anything.
The throttle cable is back to not putting tension to "fool" the idle.
After the hose vacuum leaks were addressed it seems to be idling a lot better, in the right rpm range (in the 6-800 rpm range) at least - although with a slight bit of 50 rpm hunting. It still sounds like I have a hot cam in it. lol
I need a proper tach. I gave away or lost all my old school tools like timing light, tach, etc, when I thought I was only going to drive modern cars. Here I am again, having to replace tools to get this beast back into shape.
I think I am still chasing more vacuum leaks... I need to get more brake cleaner, or ideally a little more focused applicator. I'm loathe to mess with propane, but may try that with some sort of fabricated tube nozzle that I can direct more precisely (a piece of hard brake line maybe).
I may add some additional (permanent) grounds. I have lots of scrap heavy gauge wire and copper connectors from when I did the dual battery and rear cargo power on the 200. I should be able to whip something up quickly. More grounds can't hurt. Or can they?...
I should add that I am going to clean up and cap the vacuum lines properly. This is all for diagnostic purposes.
I *think* the IAC is salvaged for now. Maybe I just hope it is...? I followed your lead and cleaned it up with some fine abrasive, gave the bearings a minuscule shot of teflon lubricant, and it is moving again (albeit not very far). Dunno, seems to do more than it did before.
I used a hardware store plumbing o-ring that is probably not the right thing, but it was what I could get quickly. It fit the groove and should hold vacuum. I can always replace it with a proper part later. Maybe.
Also, I was able to remove the IAC from the intake without removing the intake. I used some very long, thin screwdrivers that have "diamonds" embedded in the tip. Bought them at Sears years ago on a whim, but they actually come in handy sometimes - like this. The tips are ever so slightly abrasive and grippy. The screws didn't cam out and came out nicely. I did give them a rap with a ball peen hammer and a tiny dribble of Kroil (liquid, not spray) on the mating surface where the screw met the sensor. No drama.
My Dorman vacuum caps are pure shyte and leak like sieves. I pulled many off, and looped the one that I could, used a length of fuel line (new, cutoff length from a diff breather project on the 200) with fuel injection hose clamps to loop two larger ones on the intake/plenum. I put a huddexpo bb in the one small cap that I couldn't loop.
I popped the plug covers and made sure I was getting good connection at both ends of the leads. Everything looked fine.
I added a new (temporary) 4 ga ground wire to the intake, and it didn't seem to change anything.
The throttle cable is back to not putting tension to "fool" the idle.
After the hose vacuum leaks were addressed it seems to be idling a lot better, in the right rpm range (in the 6-800 rpm range) at least - although with a slight bit of 50 rpm hunting. It still sounds like I have a hot cam in it. lol
I need a proper tach. I gave away or lost all my old school tools like timing light, tach, etc, when I thought I was only going to drive modern cars. Here I am again, having to replace tools to get this beast back into shape.
I think I am still chasing more vacuum leaks... I need to get more brake cleaner, or ideally a little more focused applicator. I'm loathe to mess with propane, but may try that with some sort of fabricated tube nozzle that I can direct more precisely (a piece of hard brake line maybe).
I may add some additional (permanent) grounds. I have lots of scrap heavy gauge wire and copper connectors from when I did the dual battery and rear cargo power on the 200. I should be able to whip something up quickly. More grounds can't hurt. Or can they?...
I should add that I am going to clean up and cap the vacuum lines properly. This is all for diagnostic purposes.
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CharlieS
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- #52
I wanted to add that the one thing I found tricky was knowing how far to extend the plunger. It is infinitely variable depth, on a screw like post, so when the magnet turns it spins the screw in or out to change the plunger length. Since I didn't measure before disassembly, my best guess was that it should make contact with the orifice in the intake, so I adjusted the plunger to the length where it made solid contact with the orifice opening before reassembly.
If anyone has a IAC that is functional and can provide a measurement/picture of measurement, it could help future people who are trying to save a sticky IAC...
If anyone has a IAC that is functional and can provide a measurement/picture of measurement, it could help future people who are trying to save a sticky IAC...
CharlieS
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- Thread starter
- #53
Sorry, I missed this question somehow. No, I haven't done anything to the airflow sensor.
Also, not relevant to the idle issue, but I adjusted my tie rod so the tires are both pointed forward and not fighting each other (maybe a slight tad of toe in). Not measured, but good enough to drive the few miles to the alignment shop.
Just scanned this thread and you are getting good advice. One thing I'd add is have you cleaned the throttle body and made sure the idle is actually being controlled by the IAC instead of relying on a overtight throttle cable to hold it open? There should be some play in the cable (check all of the cables) so it can close all the way.
The throttle plate should close all the way and the IAC valve will open and close allowing air around as needed. Before installing the IAC run it back and forth a bunch of times on the bench to make sure it works.
Additionally follow the FSM tests to make sure the TPS sensor is in spec so that the ECU knows what is going on in regard to throttle position at idle.
Once these are sorted disconnect the battery to reset the ECU. It will take a handful of stop start cycles (be sure to drive around) for the idle to smooth out. Leave the AC off so you can confirm that the idle is actually at the 650 +/- 50 spec.
The throttle plate should close all the way and the IAC valve will open and close allowing air around as needed. Before installing the IAC run it back and forth a bunch of times on the bench to make sure it works.
Additionally follow the FSM tests to make sure the TPS sensor is in spec so that the ECU knows what is going on in regard to throttle position at idle.
Once these are sorted disconnect the battery to reset the ECU. It will take a handful of stop start cycles (be sure to drive around) for the idle to smooth out. Leave the AC off so you can confirm that the idle is actually at the 650 +/- 50 spec.
CharlieS
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- #55
I had the upper plenum and intake off and cleaned them with B-12 Chemtool and brake cleaner. The intake was pretty spotless when I reinstalled it.
I ran the IAC through many cycles on the bench before reinstalling it.
The throttle cable tension adjustment has been undone, it is not opening the throttle plate anymore.
I haven't touched the TPS sensor, but will do so tonight.
I'll disconnect the battery and give it a few drive cycles tonight, tomorrow before work and over the weekend. Taking it in for an alignment first thing in the morning.
I ran the IAC through many cycles on the bench before reinstalling it.
The throttle cable tension adjustment has been undone, it is not opening the throttle plate anymore.
I haven't touched the TPS sensor, but will do so tonight.
I'll disconnect the battery and give it a few drive cycles tonight, tomorrow before work and over the weekend. Taking it in for an alignment first thing in the morning.
I did all this years ago on my 94, I went and got vacuum caps off a runner and tacoma they use them in couple places on the 3vz v6 ones in the late 90s. They will seal no issues, dormans are too loose. Or loop the lines. You also have the tvv at the bottom of the driver side that is black with two ports with lines going back up to that mess you removed, I looped those ones
CharlieS
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- #57
Good to know. I'll have to look up these 4runner and tacoma vacuum caps!
Hmmm. I didn't loop the TVV.
I (it sounds like incorrectly) assumed based on my research and the FSM, that the TVV was just a bimetalic valve that opened at temp and either allowed vacuum to pass or not, but the working end was submerged in coolant. I didn't think there would be any vacuum leak once the two lines were removed.
It is super easy for me to loop it. That would be awesome if this was all it is.
CharlieS
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- #58
In case this helps someone find it in the future (it was tricky to locate), the good vacuum plugs from Toyota are the following part number:
90339-03002
Warning, they are silly expensive for what they do. Currently $7.59 each MSRP.
Picture from here: Quality vacuum caps? Dorman isn't it... - https://forum.ih8mud.com/threads/quality-vacuum-caps-dorman-isnt-it.1239959/post-13622912
90339-03002
Warning, they are silly expensive for what they do. Currently $7.59 each MSRP.
Picture from here: Quality vacuum caps? Dorman isn't it... - https://forum.ih8mud.com/threads/quality-vacuum-caps-dorman-isnt-it.1239959/post-13622912
You're talking alot about ground cables.
What is your voltage across the ... coolant?
Stay with me.
It should be zero volts, but can be up to .2VDC. Anything more and your coolant is acting as a conductor of current and not only indicates an electrical issue (obviously), but is also likely damaging other components in the cooling system, along with electrical components which interact with the cooling system.
You need two measurements: 1 - with engine off, key out of ignition. And 2 - with engine running.
Using a voltmeter, place the negative lead on the chassis or battery neg post and place the positive lead directly into the coolant at the radiator fill neck.
If you see something more than .2VDC ... report back.
What is your voltage across the ... coolant?
Stay with me.
It should be zero volts, but can be up to .2VDC. Anything more and your coolant is acting as a conductor of current and not only indicates an electrical issue (obviously), but is also likely damaging other components in the cooling system, along with electrical components which interact with the cooling system.
You need two measurements: 1 - with engine off, key out of ignition. And 2 - with engine running.
Using a voltmeter, place the negative lead on the chassis or battery neg post and place the positive lead directly into the coolant at the radiator fill neck.
If you see something more than .2VDC ... report back.
