Snorkeldepth

There's a collection of metal air pipes that run along the front of the plenum. There's a large pipe that hooks to the air suction sysem. A couple of the small pipes attach to the EGR system. They look like they're a single unit thats tied together.

I noticed a while back that at some point a mechanic had bypassed one of the EGR pipes and just ran a continuous piece of vacum tube all the way across the front of the plenum. I checked the metal tube and sure enough it's clogged tight.

When I finally solved my EGR problem I found that the EGR VSV was clogged and traced the vacum hose to the metal pipe it attaches to. The end of that pipe was corroded which I cleaned up as best I could. The corrosion apparently clogged the VSV. The pipe was clear after I cleaned it.

I'm wondering if anyone has replaced or refurbished these pipes. I'm concerned that any ongoing corrosion will cause problems down the road. I'm just thinking about fixing problems before they happen.

regularguy412

Regular vacuum hose in the appropriate I.D. will suffice. I think Toyota put metal pipes in the middle because its such a long run across there.

I'm still chasing a rough idle on my 3.0 and the vacuum lines / throttle body are the next stop.

Mike in AR

gonzo

Had a rough idle on my 3.0. ran a 1/2 can of seafoam into a fulltime vac. line at the throttle body then put a full can into a full tank of gas. No more rough idle.
Just a thought.
Good luck
Gonzo

regularguy412

Throttle body cleaning is happening tomorrow. If that doesn't do it, then it's time for seafoam AGAIN.

Thanks for the reminder.

Mike in AR

Snorkeldepth

I'm always anxious to hear about a solved rough idle problem. I hope you find the solution quick! Be sure to tell us what does the trick.

I'm about to replace all the vacum hose on the truck. Heck, it's 16 years old!!

I'll never forget the rough idle and rough acceleration I experienced the time I drove away after changing my oil and forgot to put the oil filler cap back on. I know what a compromised vacum system can do.

My biggest nightmare currently is finally getting the new engine in and still have the rough idle and stumbling acceleration that I've been attributing to the burnt valve.

I guess I'll check the price of the pipe unit and see how much it would set me back.

taikowaza

snorkeldepth-
did you ever fix your rough idle 100%?
I am still chasing mine as well. injectors cleaning and throttle body cleaning helped some, but I am still not satisfied.
ripping my AFM circuit board in hald didn't help much tho.
https://www.yotatech.com/forums/f116/maf-cleaning-disaster-86171/

regularguy412

Maybe I'm being a bit picky. The idle isn't shaking the whole truck or the engine or anything, but I can sure feel it in the seat-of-the-pants sitting at a stoplight - in Drive. The new (I mean FACTORY $$$) plug wire set has helped some of the problem. My mechanic said that a cracked plug can cause this problem , too. Unfortunately, the crack in plugs can't always be seen. I'm gonna try the TB-clean route before pulling plugs again. My hands and arms are still pretty beat up from pulling and checking them over the weekend.

Mike in AR

taikowaza

I am also trying to get to the bottom of this idle mystery. it has been fun so far.
pls. let me know if you make any discoveries.
can the a/c compressor affect the idle?

regularguy412

Cleaned the TB AGAIN! today, even tho it didn't look like it needed it. No change.

My mechanic still thinks it's a secondary electrical issue,, like: plugs, wires, etc. I'm beginning to wonder if it could be a primary electrical,, like the alternator not putting out as much at idle and consequently not driving the coil as hard.

Might just go ahead and pull and replace the plugs AGAIN. I only cleaned and reinstalled them, last weekend. Difficult for me to believe that plugs could do this. Put them in brand new in January, this year.

On the a/c compressor issue: I guess it could cause a problem ,if it was goin out and putting more strain on the belt. However,, the idle-up valve is supposed to increase the idle to compensate for the extra load the compressor puts on the engine. You'd think that if it was the compressor doing it, the compressor itself would make some tell-tale noise.

I'll keep ya posted.

Mike in AR

taikowaza

yep I know the feeling. the 3vze with headers is RARING to go but something is holding her back..
here is what I have done so far, let's compare tasks and make sure we cover everything.

-injectors ultrasonically cleaned.
-new AFM (tomorrow)
-new wires
-new plugs
-new fuel filter
-new oil filter
-new cap
-new rotor
-new battery
-seafoam smoke destruction
_tb cleaned

GEEZ! that is a lot of new stuff and $$...would like to get some good performance out of her!
I am not sure of the best way to check vacuum lines. One post recommended spraying TB cleaner all over the place while running and listen for surge but I think that way sucks.
also, the A/C is a mess. it blows cold but now it is stanking up and also noises are coming from the passenger side. WHen will it end?
is the consensus still to spray deeodariyzzza into the vents?
I will celebrate like 1999 once all is taken care of...
but I must admit I have never been so excited about my ride.

regularguy412

I've not had the injectors out to be cleaned and I still have the same AFM. Other than those two items,, I've done the same things you have ( tho it 'may' be time for another fuel filter -- last changed it 40,000 miles ago).

I may try lubing the AFM door, cuz I 'really' don't like digging around in there to change plugs. Aluminum heads are skeery. However, I'm not sure the AFM door would affect the idle too much. There's not much air pressure on it at idle.

Last nite I printed-off the engine troubleshooting chart from the 1993 FSM thats online at UTulsa. One of the first things it says to check on a rough idle is the coolant sensor. I've wondered if mine has been going out, but the guage seems to work just fine. That is to say, it moves up in proportion to the warm-up that the engine is going thru. The next thing on the list to check, according to the FSM, is the EGR system. I already had that apart back in January when I put in the new spark plugs,, but I didn't really 'check' it. I did a cursory cleaning and put it back together. So last nite I also printed=off the EGR testing/cleaning part of the FSM, as well.

Guess I've got my weekend planned for me.

Mike in AR

regularguy412

Well I couldn't wait any longer, so I jumped on the 4Runner again this morning. Took out the MAF. Checked it with the ohm meter and lubed the flapper door. Everything checked OK. No improvement in the idle miss.

Took the EGR valve off and cleaned it. Only got a small amount of gunk out of it. The valve appeared to be seating properly with vaccum applied. Put it back on the engine and went thru the check procedure found in the FSM. The valve and the vacuum controller appear to be working properly. No change in the idle miss.

Next item on the FSM Troubleshooting chart was the Engine Coolant Temperature Sensor. Not too expensive -- about $30 locally. Let me tell ya, standin' on yer head on top of the plenum with yer back against the open hood for an hour is no fun. I wrapped a 2' x 2' piece of 3/4" plywood in an old blanket and laid it across the top of the passenger side of the plenum, letting the front edge hang over the radiator. Getting TO the sensor plug and getting it off is a major PITA. Just no room for a hand in there. Finally flattened the end of a wire coathanger with my 3 lb. hammer and fished it down there to release the clip. I got it unclipped, but it wouldn't come off. There was room to pry on the open end of the clip with a long, flat screwdriver and it finally just popped off. Getting the sensor itself unscrewed was pretty easy. A deep socket that fits a 3/4 nut will go right down over the whole thing, clip point and all. An extension for the ratchet and a swivel on the end works just fine.

Unfortunately,, THAT didn't fix the problem. I'm done for the day. Will keep ya posted.

Mike in AR

gonzo

Mike. I always put just a touch of anti sieze on the spark plug threads. Makes it SOOOOOOOO much easier to take out the next time. Just a dab, Be careful not to get any near the end as it will cause it to misfire.
Been doing that for years and never had any problems with plugs in alum. heads.
Good luck

regularguy412

Thanks for the post Gonzo. As much as I dread it, I suppose I'm gonna pull the plugs AGAIN, tomorrow. Maybe there's enough miles on this engine that it is just gonna mess with the plugs after about 6,000 miles. The NGK's I put in back in January show NO wear. Still gauged at .031,,just like they were when they went in. There was a small amount of carbon on one side of the insulator on them. From what I have read and seen online, this effect is usually caused by some valve guide wear letting a minute amount of oil seep thru on the intake stroke. That's understandable, since this engine has 185,000 miles on her.

Mike in AR

taikowaza

more idle searching quests!
3vze...
replacing my AFM made a positive improvement in my idle.
The other thing that may have helped...
was that the white inlet into my K&N wasn't connected to the black tube from ? (not sure what it's called).
replacing my K&N I noticed that the white inlet had nothing attached...
the idle is the best it's been yet.

a/c squeaks...
can I lube it or do I need a new compressor?

regularguy412

OK boys n girls,,, don't ask me why or how, but the mysterious miss at idle and off-idle turned out to be spark plugs. Just installed them in January and made a couple of road trips on them,, then just normal driving around town and short, out of town trips. They started this missing about a month ago. Wasn't too bad, but seemed to get worse,, AND more annoying. Mileage dropped about 1 mpg around town, too.

I installed NEW plug wires from the dealer and put in new NGK's today. I had installed new plug wires last September, but they weren't OEM parts. The whole set was only about $35.

Mike in AR

taikowaza

feels so good to finally find the culprit!!!
nice work
for me it was combo throttlebody/injectors/plug/wire/cap/afm/vac
and i am finally happy again
t

Snorkeldepth

My rough idle won't go away until I'm running on 6 cylinders again. But, the aggravating thing is I managed to bring back my Code 71.

I'm hoping it's just a wire that pulled loose from the temp sensor connector that didn't get put back together well enough. I may replace the connector. Can you buy just electrical connectors without buying a harness or the pieces the harness attaches to? Maybe somebody has a good source for high quality, hi temp electrical connectors??

Good luck with yours!

taikowaza

dude that sucks!!!!
good luck getting the idle back. it can be so frustrating.
Mine is almost purrfect except for when I turn on the A/C.
I want to adjust it...do you know how the A/C idle adjust works?
is it the same principle as the regular idle speed on the throttle body?

everytime the A/C compressor kicks on, it wreaks havoc with my engine idle. anybody who knows about a/c idle speed on the 3vze I'd love to know my next course of action- do I have to replace my compressor or can I tweak/fix this?

I just filled it with juice and it is COLD! only prob. is that it's sometimes noisy and it messes up my idle a bit.

Snorkeldepth

Yep, the curse of the returning code 71 was just the temp sensor connector. What a relief.

I don't know about the a/c idle question other than there is an a/c idle up that increases the idle when the compressor turns on. Have you checked the FSM?