In Moab - 3VZE idling poorly or not at all

[ScaldedDog]

My 4Runner sat for the last 5+ months, but ran fine on a short test drive around the neighborhood the other day. Get to Moab today and it would barely idle when I went to take it off the trailer, and mildly backfired a time or two when applying throttle at idle. Seems to run fine when on the throttle, and idled OK once or twice this evening.

What I've done:

1) Disconnected the cold start injector connector, with little or no change. It *seems* like it's idling rich, so I suppose the CSI could be leaking. Haven't been able to clamp off the fuel supply to the CSI yet.

2) Looked at the volume air flow flap with the air cleaner off. When idling poorly the flap oscillates slightly in time with the engine lope. Open the flap with my finger a little and the idle smooths right out. Apply throttle and flap opens more and the engine runs fine. Is this oscillation a cause of the slow lopey idle, or an effect?

The other thing to know is that I last put gas in it in August, and the fuel in it then was a month old, or older. (Yeah, I know, I need to wheel more...)

Thoughts? I'm thinking I'll throw a bottle or two of HEET or Seafoam (or HEET and Seafoam?) in it, figuring that can't hurt. Not sure what else to try at this point.

Mark

 

[Lastresort576]

could certainly be fuel related...but it sat for awhile...how is the intake plumbing up the filter, any rodent nest obstructions? a nest could totally cause idle to get messed up. I would start simple ie things related to the vehicle having sat for some time and go from there.

 

[ScaldedDog]

Thanks man. It was inside, and I'd gotten it ready for this trip back in December, so it's quite clean.

The VAF is a meter, right, so it isn't *deciding* how much air is available at idle, it's measuring it. By pressing it open a little, I'm telling the ECU more air is present, and it idles better. Why might that be?

Mark

 

[DaveInDenver]

If it sat for that long it seems like it's gummed fuel, so clogged fuel filter, injectors, etc. A leaking cold start is plausible.

Do you have a check engine light on?

The VAF sends a voltage proportional to the amount of air that is being sucked in. The ECU uses this to decide how to meter the fuel and spark. But it also factors in throttle position, engine temperature, O2 reading, distributor position and a few other things.

Pushing the flap isn't quite exactly like pushing the throttle plate on a carb. The position of the flap will vary with the engine lope but also will react to the position of the throttle body plate.

I attached the PDF from a 1993 3VZ FSM if you want to test it. But I don't think it's the problem other than in a general way from sitting. Meaning *maybe* corrosion on contacts or something. Electronics wouldn't suddenly fail just sitting unless the truck was hit by lightning. It may help to rock or unseat/reseat connectors.

I also attached a few diagnostic and troubleshooting sections from the FSM. A multimeter and a paperclip (use in the diagnostic port to put the ECU into test mode) may give you some ideas.

 

[ScaldedDog]

You rock, sir. I really appreciate the effort you put into that.

I'm leaning towards fuel. It idled much better this morning, and still runs fine, otherwise. I put a can of Seafoam in it, figuring that cant hurt. We'll see what happens today.

Thanks!

Mark

 

[Squishy!]

Those old O2 EFI systems do weird things when the O2 sensors start to go out. It's a common problem with 22RE, but I haven't seen as common on the 3VZ, but that could be a production percentage thing.

 

[ScaldedDog]

Thanks guys. It worked pretty much as it always has all day today. Warm starts result in a surging low idle, but that isn't new. The rest of the time it idled fine.

Thanks for the help! A little Moab sunset pron for your help

Mark

 

[ScaldedDog]

I don't think it had anything to do with the acute issue I had a few days ago, but I found one of the VSVs is broken. The one with the green connector is related to the EGR, but do any of you know exactly what it does? Extra credit if you know the symptoms resulting from a broken top.

Mark

 

[Squishy!]

Those are just the atmospheric vents. Basically a small filter.

 

[ScaldedDog]

Thanks Justin!