Erratic idle and stalling at stops (1 Viewer)

[Traakon]

I'm chasing the same thing right now, except one morning when I fired her up it just wouldn't hold idle. No braking issues, no recovering as it dropped, just straight to dead once off the throttle, every time, 100% repeatable condition.

I replaced the PCV and VCV with grommets and hoses today, and that definitely needed to be done as some of the hoses and the grommets were brittle. But it didn't affect anything. So I have an IAC on order, which I got for $150 so not bad and hopefully that's the fix.

I'm too lazy to look at the FSM right now - what's the gasket for with the IAC since it's a plug in component?

The IAC uses an "O-Ring" not a gasket. The gasket in the post is for the Oil Level Sensor (OLS) that I now need to address.

For your '95 you have the less expensive/easier to locate 22270-66011 IAC. Seems like we few folk who have the '93-'94's get to have the more rare and more costly parts for the same motor.

As strange as it seems don't forget to look at the hose/check valve/grommet on the brake booster and the booster itself for possible vacuum leak areas.


Tip for changing your IAC. Use a 1/4" drive ratchet with a 12" extension, a 1/4" short socket and a #2 Phillips (crosspoint) bit in the socket. The extension will give you the reach over and back to the lower screw and by using the ratchet you can get enough pressure in on the screw to keep the bit engaged in the screw and the leverage to turn it free. I placed a small neodymium magnet on the side of the socket to make sure I did not lose the screw or bit down the black hole under the IAC.

 

[Nay]

The IAC uses an "O-Ring" not a gasket. The gasket in the post is for the Oil Level Sensor (OLS) that I now need to address.

For your '95 you have the less expensive/easier to locate 22270-66011 IAC. Seems like we few folk who have the '93-'94's get to have the more rare and more costly parts for the same motor.

As strange as it seems don't forget to look at the hose/check valve/grommet on the brake booster and the booster itself for possible vacuum leak areas.


Tip for changing your IAC. Use a 1/4" drive ratchet with a 12" extension, a 1/4" short socket and a #2 Phillips (crosspoint) bit in the socket. The extension will give you the reach over and back to the lower screw and by using the ratchet you can get enough pressure in on the screw to keep the bit engaged in the screw and the leverage to turn it free. I placed a small neodymium magnet on the side of the socket to make sure I did not lose the screw or bit down the black hole under the IAC.

Thanks for the IAC removal tip and clearing up the gasket - I didn't follow that part. I did change the VCV/hose/grommet on the brake booster hoping that was this issue along with PCV and those hoses, although when I removed everything on the booster side it looked in pretty good shape so I wasn't too hopeful. Didn't examine the booster at all, and you're right that I have the cheaper IAC.

Since mine is dead on start - I can only get it to fire up with some throttle - I'm thinking some electronics have to be involved. There's just nothing intermittent or erratic and everything otherwise runs perfectly. I'll post up once I know if the IAC solved it.

 

[bahamasair]

How much throttle do you have to give it? Is it enough to switch the fuel pump to the high speed circuit? If so I'd assume it's something to do with the resistor circuit that drops the fuel pump voltage for idle. You can bypass the resistor so it stays on high speed and see if it runs normally then. If so you know that's where the problem is.

 

[Nay]

How much throttle do you have to give it? Is it enough to switch the fuel pump to the high speed circuit? If so I'd assume it's something to do with the resistor circuit that drops the fuel pump voltage for idle. You can bypass the resistor so it stays on high speed and see if it runs normally then. If so you know that's where the problem is.

Has to be from starter engagement, almost like managing the choke on a weed wacker. And then I need to keep it around 1K RPM, left foot on the brake while managing throttle. So this does sound like it could be the issue. Not a bad idea to change out those parts so may just do that before I lose return rights on the IAC. Thanks for the suggestion - any tips on which resister we're talking about if you happen to know offhand?

Edit: I see the fuel pump resistor in the FSM.

 

[Nay]

Changed out the IAC.

First, whoever designed that lower bolt as a phillips head screw that you can't get to straight on, owes me like eight beers. I had to get seriously creative after it stripped to find a way to get a screw extractor in there by daisy chaining cordless drill bit extenders (I have a bunch of those things from old drills) and then grinding an edge of the screw extractor to fit in the end of that. I spent like 2.5 hours. Those bolts have been replaced with hex heads and now it takes about 2 mins to swap that thing out.

Second, after the IAC swap, it fired right up. All good. Except that idle kept rising very slowly, up to about 2,200 RPM. I figured maybe the ECU was learning or whatever, so I took for a drive and it wouldn't drop below 1,200 RPM. Back in the driveway, in park (or neutral), and it sits and revs itself, up and down, up and down. 1,500 RPM to 2,300 RPM. I disconnected the battery for a reset and same thing: never below 1,200 and in park or neutral it would rev up and down between about 1,000 and 1,600. So lower RPM, but same thing.

OK, time to factory spec test the new IAC. Resistance in spec at all S terminals at about 20 ohms (spec is 10-30). The old IAC specs out as well for resistance test. So I put the old one back in. Same thing - now it fires up just fine, and revs itself up and down. Unplugged the IAC altogether and it does the same thing.

So at this point, it's acting identically with new IAC, old IAC, and no IAC (IAC installed, disconnected). But the symptoms have changed from won't hold idle to what seems to be no idle management at all. I'm thinking it must be the connector - one slot was off from the others so I straightened it out, but that had no effect. I used some spray contact cleaner before reconnection, but didn't otherwise do anything to the connector. I'm suspecting bad contact, and I'll tackle that in the morning to see if there's some corrosion, although the old IAC pins didn't look bad.

Any other thoughts?

I know the main harness is often a culprit, but mine was checked and heat wrapped when the PO had my 80 baselined at Slee. And there's nothing intermittent - it's always same condition, even though it's now a different condition.

 

[Tools R Us]

Any codes? Have you checked the TPS?

 

[Nay]

Any codes? Have you checked the TPS?

No codes and none from the start. I'm going to check the TPS today and will report back. Now that I'm in the process of replacing things that apparently were working, I should continue .

 

[too tall]

I once had an issue with a stumble/weird Idle on my wife's 80. No codes , checked every sensor associated. Replaced intake tube , tps and a multitude of other things until I decided to check inside the distributor. The magnetic pickup had come unglued from it's mount inside the dizzy and was moving around occasionally arcing out or touching the reluctor. I replaced the distributor and all was well. I was ready to sell it the day before and was really close to giving up . Might be worth a quick look ?

 

[Two 3FEs]

I have a '92 FJ80 with all the identical symptoms. Replaced just about all the same parts as Nay from a 91 next to it. so what does this 'magnetic pickup had come unglued' look like? I was thinking yesterday to look at the dizzy cap and have a new cap in the box. I also have a new in line fuel filter inbound and really praying that is the underlying issue.

 

[Nay]

I once had an issue with a stumble/weird Idle on my wife's 80. No codes , checked every sensor associated. Replaced intake tube , tps and a multitude of other things until I decided to check inside the distributor. The magnetic pickup had come unglued from it's mount inside the dizzy and was moving around occasionally arcing out or touching the reluctor. I replaced the distributor and all was well. I was ready to sell it the day before and was really close to giving up . Might be worth a quick look ?

Thanks - I'm going to head down that road next if needed. Although the repeatability of symptoms I have is 100%. It is acting like an electronic system missing a signal and pinging around looking for it. I'm going to post a vid.

Are we talking the distributor itself?

 

[Two 3FEs]

apparently so.

 

[Nay]

Here's a vid of what happens at cold start. Idle starts high and very slowly increases on its own. Dropping into gear and it goes down to 1,100 - 1,200. Right back up shifting to park or neutral, and then towards the end it is finally high enough to start pinging up and down.

 

[Two 3FEs]

mine does exactly the same thing. going for some electronics cleaner and the Temp Sensor connector lost its clip. have been using self sealing silicone Rescue Tape on all the connectors

 

[Nay]

Ok, I'm going to hone back in on cleaning the connector contacts on the IAC. Because my symptoms changed and I can't make it go back with the old IAC, and it does it with the IAC disconnected completely I think a contact/connection problem has to be ruled out.

 

[Two 3FEs]

and all this happens once it gets warmed up and worse when hot? mine does. I just made a 1 mile round trip to hardware store for elect cleaner and a bottle of STP fuel injector cleaner to hopefully clean out that inline fuel filter until the new one gets here mañana. these are brand new 4 port aftermarket injectors BTW. But maybe crud somewhere in the fuel system.

 

[Two 3FEs]

I just cleaned the electrical connectors on the temp sensors then taped them in tightly with that Rescue tape. Now after a start while still warm no problema, idle was 1200, drove it around a long block with a slight uphill (following a Benz GL450 and drooling) pulled into driveway and no wanting to stall out, idle was at 1500 but smooth. keep your fingers crossed those connectors just might be the issue.

 

[Two 3FEs]

oh and don't forget the fuel injector cleaner in the tank but that would take awhile to do its job.

 

[Two 3FEs]

going to take a test drive down to the creek and back uphill for a few miles to see if it all holds.

 

[Nay]

I checked the TPS and everything in spec, including verifying 5V at the connector. IAC connector showing 12V at both B terminals.

So....

I figure it's time for a bottle of engine cleaner and a fresh tank of fuel because everything else seems to be testing out and all of my wires and connectors look good. I drive the 7 miles down to O'Reilly including interstate speeds, pick up a bottle of Lucas, head across the street to Shell, all symptoms still intact pulling up to the pump.

In goes the Lucas and 16 gallons of premium so 8-9 gallons of the previous fuel still in there. Start it up, engine starts to rev, drop it immediately into drive, and idle drops a bit right away down to 1K and it's not as "lurchy". Drive a quarter mile to the store, hop back in, fire it up....

....normal. Dead normal. Idle at 800 like it always is, no revving or anything else. Idle in park staying around 1K and I can feel it being "managed". I'll take it out again once it cools some to see if it holds. If so, I have three realistic theories:

1) the fuel stuff was a total coincidence and the ECU was relearning the new IAC, which is also why the old IAC generated the same symptoms when I reinstalled it. That's the pulsing RPM aspect;

2) I inadvertently filled up last time with the "E15" that Kum & Go sells that is for 2001 and later vehicles only, which I like in my Sequoia because it's $.10 cheaper and a little higher octane than the low grade 85, and that caused things to be unhappy;

3) It was just a straight fuel system issue that the additive helped free up.

My gut is #1. That's awfully quick for a fuel additive to work. And the threads I could find are all for pre-95's. I don't want to think about option 4, which is it will be back when I go out and fire it up in an hour or so.

 

[Two 3FEs]

I did the test drive down the hill to the creek and back up. Idling was fine at the beginning. on the drive backup I put the pedal down and those 4 port injectors just make it roar. Passed a 4Runner still on the hill. This thing is a hot rod de-smogged and injected. The idle pulling into driveway dropped to stall but I will address the IAC when the gasket comes in. The old gasket had a rubber sleeve to slide over the sensor that was black carbonized.