camo31_10.50

okay so now that i've gotten my motor back together and running...i find out that it won't idle when warm.

idk if this is something that got fiddled with during the rebuild, or before...because i bought it with a bad knock in the motor, so i started it to be sure of the knock and pulled it into the garage. so it never got the chance to get warm.

it's definitely noticeable though, it will idle at around 1100rpms when cold...idle just fine just like it should, then after a few mins..it begins to drop down a little...then it drops off dramatically and kinda sputters, then just dies.

i've pulled out my cold start injector and it was nasty lookin..how do i clean it properly without damaging it, and without sending it off to WitchHunter?

no codes are being thrown...so no CEL.

i want to start simple, then go to the more complex things that it could be.

it's not spark...cuz if i give it ANY throttle then it will idle up to about 750-800 where it should be and it will idle fine.

i've messed with the warm idle screw, and nothing happened.....?????

i haven't checked for vacuum leaks yet..but i will tonight.

i seen another guy with the problem, and someone said check your grounds..so i'm going to try that in a minute and see what happens.

camo31_10.50

i checked my grounds...all seem good?

checked battery to body, body to motor at the back of the upper intake manifold, and then motor to frame..i also moved this one to a better location, it's by no means permanent..but it was easiest to get to (it's one of the A/C bolt locations.)

i took my air filter off, and i noticed, that when i push the "flapper" in a little bit, the truck idles GREAT!!!!!!! if i push it in too far, then it gets progressively worse..

so does this mean it's running rich at Idle? since i'm basically leaning out the mixture by pressing the flapper in a little bit.

i never seen my Cold Start Injector drip or anything when warm, (didn't even spray actually...i don't even know if it works, but it starts fine cold and warm).

so that leaves me with one other option (in my head)....Injectors.....i know it's possible that one of my injectors could be seeping a little bit of fuel into the cylinder...i would just like to rule out anything else it could be first.

anybody got any ideas?

pb4ugotobed

First thing's first. air flow meter. http://personal.utulsa.edu/~nathan-b...33volumeai.pdf
If that's ok, Check fuel pressure. I don't think you'll find anything here, but it's worth a check, and will let you know if you may have future pressure problems.
Check the EGR system.

I'm sure this won't be a vacuum leak. A vacuum leak will make the engine idle HIGHER not low. It is possible you have a vacuum line routed to somewhere it shouldn't be, and it's triggering some valve and creating the low idle, however I would doubt a leak.

When you took the motor apart, did you take all the vacuum lines off of the intake plenum? Or did you do the smart thing, and only take off the ones by the throttle body, the PCV hose, and the big one on the EGR modulator, and leaver ALL of the other ones connected and flip the plenum over and lay it on the passenger fender (trust me it's plenty out of the way here, you can pull the entire motor out and not touch 95% of the vacuum lines.

camo31_10.50

well i took all of my lines OFF of the intake manifold :/

but i also labled em!!!!!!!!! there was a couple however that i was unsure of, and put them where they fit...because they wouldn't fit snug anywhere else.

i have DELETED my EGR...i took off both pieces that bolt to the passenger exhaust manifold and intake, then i unbolted the piece right about the timing cover....all vacuum lines were plugged with Screws and do not leak.

Thanks bro!!! keep the suggestions coming!!! where should i check the fuel pressure at?

pb4ugotobed

There will be a bung near the distributor. This will give you fuel pressure at the end of the fuel rail.

Or you could disconnect the hard fuel line but really that's a pain in the ass.

Does the check engine light come on at all? Any funny noises? There's a good chance you've mixed up some vacuum lines, but it's hard to tell.

Definitely check the resistances on the air flow meter. It's rare to see them go bad, but if you mess with it and it runs superb, then you might be on to something there. Testing the meter itself would be a good check to do, and only take a few minutes. Just make sure you unplug the connector before you start checking the pins at the connector.

I wouldn't have deleted the EGR though, this may play a part of it.

And how about the o2 sensor? Might be worth checking that as well

pb4ugotobed

The thing you gotta keep in mind here, cold idle is good. Cold idle is in closed loop mode, meaning it's basically bypassing ALL sensors until it gets up to temp. Then as it gets up to temp, it starts relying on all of the engines sensors to tell it what's going on, so that it can compensate and do what is necessary to keep the engine running properly. Like I said, this doesn't sound like a vacuum leak, but rather one of the ECU inputs most likely.

camo31_10.50

well i thought the O2 sensor on these motors just told the computer that it's running rich/lean...and the computer didn't compensate for this, it just throws the CEL??

i am getting NO CEL unless the key is on and the motor is not running...which is normal right, because you have the key ON...and the motor isn't running..which to the computer, means something bad happened lol

lots of people have deleted their EGR the same way, and have had no ill effects what so ever.

you say "unplug the connector before you start checking the pins at the connector". how am i going to check the pins, unless i unplug it lmao

no funny noises other than an exhaust leak, however it is an OPEN exhaust right now....i have a new downpipe on the passenger side manifold, and the driver side manifold is attached, but not attached at the Cat.

got a good Vacuum diagram?

pb4ugotobed

If the o2 tries to overcompensate then it can kill the engine, or at the least make it run absolutely horribly.
Unplug the connector. In the air flow meter will be some pins sticking out, inside the little part where the connector goes (that the connector plugs in to). This is what you want to test.

There is no such thing as a good vacuum diagram for this engine. It's a nightmare. Real pain in the ass. Your best bet if this is the case is to find someone else with a 3 liter, and use compare and contrast to figure it all out. The diagrams all pretty much suck.

camo31_10.50

hmm...i'll check the O2 as well then!

ohhh okay i see.

awh darn :/ now i gotta search high and low for an unmolested 3vz :/

camo31_10.50

and what?



so i started it today...cold start...and it cranked for a while..and wouldn't idle cold...then it idled fine?

now it will idle fine for a little bit...then start cutting out?

i just remembered something that could be the problem......
when i was putting the fuel rails on and such, there was a union bolt missing at the back....it attached the line that was coming from the driverside rail to the passenger side rail.......the original bolt that goes there has a single large passage in it....well i found a different one off of a Geo Metro parts car, it had 2 smaller passages....i'm thinking that these 2 smaller passages are not allowing the right amount of fuel/fuel pressure..and that's what is causing my problems...............i think

pb4ugotobed

(told you to check fuel pressure)

camo31_10.50

lmao yes but i haven't had a chance yet dangit lol

to me it seems the union bolt from the metro would decrease pressure for sure..lol

camo31_10.50

mmk so i replaced that bolt...and it didn't seem to have an effect honestly.

i started testin my AFM after that and this is what i found.


everything was within the ranges,
except E2---VB....it's supposed to be 200-400ohm, can't remember what i got but it wasn't near that..

and E2---VC...supposed to be 100-300ohm, i got a big fat 0


so i guess that means my AFM is bad, right?




i don't know why it was fine before the rebuild, and not fine after it though????? only thing i did was take the intake as one piece and lay it in the back seat, but it did fall into the floor of the 4runner once or twice, i guess it COULD have POSSIBLY knocked something loose inside?

there's also a hole in the black piece on top!?!?!? idk wtf is up with that......

pb4ugotobed

a hole in what black piece on top? Can you load a picture?

camo31_10.50

my cell phone is broken so no.

it's the piece that is sealed with Silicon...it's black, squared on one end, rounded on the other...

i'll try to find a pic on here...

TNRabbit

He's talking about the black piece on top of the VAFM; it's supposed to be pristine in there, so if there's a hole, you've probably got moisture & dirt. That would pretty much do it in.

camo31_10.50

that's what i was thinkin TNRabbit.

i'm going to try to get a AFM from a junkyard and see what's up.


i guess if i can test it like i did this one, and it tests GOOD...and it looks GOOD...i'll get one.

if it doesn't fix the problem, i might take it back..idk yet...i'm extremely tight on cash right now...

camo31_10.50

ahhh the sweet smell of SUCCESS!!!!!!!!!

turned out it was the VAFM...got a used one from the local junkyard...and honestly, it looks BRAND SPANKIN NEW (they didn't clean it or nothin, i'm the one who pulled it.)

swapped my old one out for the new one, and when i first fired it up...it's like nothing changed...then i fired it up again...and it idled smooth!!!! then it got rough, and i noticed a vacuum line that had come unplugged, so i plugged that back up..and then it REALLY idled smooth.

only thing i noticed is that sometimes the idle will drop real low...you can give it a lil gas and then it jumps up a bit and settles around 750-1000rpms and idles smooth.

hopefully i can get a dang exhaust system on it soon it's LOUD.