coltonstewart

I suspect a bad VAFM because of non sustainable idle and terrible fuel ratio. I have a few ideas but perhaps the Vafm is the culprit. The FSM is kind of obscure in the specifications.

It says: E2 - VS with vane closed = 200 - 600 Ohms & E2 - VS vane fully open = 20 - 1200 Ohms. Moving in a wave pattern as you slowly open the vane.

This video I assume represents the correct values (@ 2:55):
And this video is more like what mine shows:
My VAFM test actually was just like the second video, except mine seemed to have a couple deadspots. However, I couldnt rule out my cheapo multimeter causing this. What do you guys think, do you have a running system with those low test values?

coltonstewart

Bump?

Punchy

The second video is close enough.
A analog ohm meter is best for testing dead spots.
No need to test for full open, If any of the test
Vs - E2 200 - 600
Vc - E2 200 - 400
VAFM body to any pin = infinity
Not in range of the above = fail

What are you using to measure fuel ratio?
You mention bad, Rich or lean?

maxscott

I went 3 clicks lean and it run great got some more mileage

coltonstewart

The test I am referring to is the second chart of tests in this FSM link: http://htftp.offroadsz.com/marinhake...92volumeai.pdf

And my fuel ratio is suspected rich, because the spark plugs are wet with fuel, the exhaust smells sort of like 2 stroke, exhaust is very hot and forcfull and at night sometimes have seen sparks shooting out the tailpipe in high RPMs, and the oil is heavily polluted with gasoline at this point from troubleshooting after the rebuild. Sounds like its starving for air at idle, and intermittently backfires fuel into the plenum.

I have checked EVERYTHING including the electrical connections from the ECU to the sensors. My main problem is that I have been on budget and have several replacement parts from the junkyard. The VAFM is a yard pick and has never been drive tested. I also have to rent out the fuel pressure guage from the auto parts store. My replacement Fuel pressure regulator is faulty i think, because I can suck air past the diaphram (although i havent noticed any fuel come out the vacuum port).
[BTW for posterity, all the FSM and chiltons diagrams all over the internet of the the VAFM pinout are wrong... All except for this wiring diagram: http://www.snjschmidt.com/wiring/Eng...rol_3vze_2.jpg Which labels the pins on the VAFM. E1 and FC are pins 1 & 2 respectively. everything else falsely has FC switched as pin 1]

So I think it comes down to FPR, or VAFM. One time I unplugged the TPS while the engine was attempting to idle, and she roared to life and had a stable idle! So i replaced the TPS with a yard pick that electronically tested good and its back to poor idle... and the wierd thing is i cant get it to repeat the roar to life since, TPS plugged in or not. This is another reason that i thought the VAFM, which shares a common sensor ground (E2) with the TPS, could be the culprit that was affected into functioning correctly when the TPS was pulled that one time.

Oberon

Did you ever come up with a solution here? My truck has the same symptoms.

Chuck78

I'm dealing with the same or similar symptoms here, 2 years later. We deleted the EGR today, still doesn't idle once it's warmed up to 60% of normal temperature. Wife ordered a new AFM, as I believe it was E2-VC which was supposed to read 200-300 ohms, read 2 or 3 ohms iirc...
Then I did a compression test on it. 279,000 miles and had 167-178psi on 5 out of 6 cylinders, I was pleasantly surprised! Until I got to #6, 40PSI!!!!

Off came the intake piping (throttle body side was ripped up and held together with electrical tape, potentially leaking unmetered air...$14 SKP(?) replacement from Parts Geek vs $96 Dorman...).
Then the valve cover. Cold valve clearances were all not terrible I'll say, EXCEPT #6 exhaust... Not tight tight, bucket spins, but my thinnest feeler gauge wouldn't slide under the cam lobe no matter what position the adjacent lobe was in (there is a proper position.
Ordered the proper 3VZE Toyota lifter bucket / follower depressor tool that is cam shaped and looks like pliers or tongs, with the holding tool (looks like a lifter bucket depressor for motorcycles but thin like thicker sheetmetal).
The special tool is absolutely required for cylinder #6 due to the brake booster being in the way of makeshift methods. Even then, cam lobe pointed straight up or towards passenger side helped, to angle tool towards the front a bit to be able to rotate it down to the valve cover gasket surface where it needs to be.
Insert hold open prop tool on back side of cam on edge of bucket, paying attention to the angle the handle portion is at when the other portion is parallel & perpendicular to the lifter bucket. It'll pop out if it's not square and sitting properly on edge of bucket. Then remove the depressor pliers/tongs tool, as you'll need that space to pull the 34mm diameter valve shim out.
You should've measured your clearance cold before this step. In my case, I had NONE, so I knew I need a shim at minimum the .22 - .32mm thinner, per the clearance specs if I was at zero clearance but not held open... It was held open on mine.
2.75mm valve shim. Precision ground it down to 2.45mm. Great, I have a little clearance now! Crank engine over several times with ignition unhooked, to seat valve after spraying ATF into cylinder to help clean carbon buildup off the valve and seat, guess what?! No more clearance!!!
Ground and polished shim down to 2.14mm, I overshot the 2.20mm smallest shim size available. Cranked it over several times, still have .20mm cam to shim clearance!!! Compression test @ 150psi!!!
Started up and warmed up better, stronger faster idle, more power driving.
Once temp gauge was halfway to normal, more rough idle again!!!!!
Thinnest valve shim available means the EGR cooked the #6 exhaust valve, and the face is just hammered, mushroomed out, tuliped I believe is the proper term... Needs a valve job due to the EGR existing or malfunctioning.
AFM arrives tomorrow, maybe that'll help, but I haven't compress tested #6 after the test drive, but I suspect the valve is back to not sealing well again, or hot clearance still allows it to hamg open a slight bit despite dropping down TWELVE SHIM SIZES!!!!

These 3.0L V6's really get a bad rap, but I don't think they're really a bad engine at all. It's a bit difficult to access the valve covers/cams to perform a valve adjustment having to remove the EGR system, the intake piping, and the entire upper half of the intake manifold all associated items attached to it, and therefore the valve adjustments never get done on them, and the engines suffer problems because of it. The EGR causes cylinder #6 to run hot especially whwn the EGR is malfunctioning, which the exhaust valve on #6 suffers the bulk of the consequences for this.

EGR delete and Pair valve delete you're a little bit better access to the engine and eliminates this liability, then one just needs to do valve adjustments at proper intervals and timing belt jobs, and I think these engines would do excellent for the long term. Advancing the ignition timing higher than stock as well as playing with the adjustment on the airflow meter itself with the silicone on top piece removed, will give you a little bit better performance as well.


AFM arrives tomorrow, but I'm not holding my breath for it to be the magic bullet. Although the reading that was off has to do with the reference voltage signal, so perhaps that could be a bit off and causing all of this.

Chuck78

So at first I was a bit upset from not looking into the VAFM testing procedures and readings more thoroughly. The 1975-1989 Clymer's Super Shop Manual, which is otherwise awesome, has very little info on the fuel injection system and other engine management on the 1988-1989(-1995) 3VZ-E engine, and no VAFM troubleshooting procedures that I could find. Neither does the Haynes manual for 1979-1992 pickups that I have... Factory Service Manuals are hard to come by, and even finding a reliable download source leaves you wondering if you're on a scammer site due to all the extreme amounts of ads everywhere including all the formerly good old forums...

I'd read one post saying "The 3VZE AFM testing is basically the same as the 22RE AFM," and several others almost mirroring those sentiments. So I tested it per 22RE VAFM directions and specs, which are all over the internet, and said "wow, E2 to VC is supposed to be 100 to 300 ohms, and I get 4 ohms!!!! Everything else tests good, but this is way off, so let's buy a $100 hard to find reman 3VZE VAFM..."

Today I spent a long time searching for a better FSM download, as the only one I have does not have the first or last pages, so it's 1700+ pages to sift through, and is only missing the index and the table of contents!!!!! 65-75 minutes of futile searching of dead links and redirected adware links of basically dead links, and I went back to the download I had and started scrolling page after page rapid fire until I found the EG1 - pg 194 section, but realized it was the exact same, and I then realized EG1 must be engine #1, so jump ahead 100+ pages and I'm in EG2 which is the 3VZE. EG2-236 on the 1993 Factory Service Manual that's floating around has the actual 3VZ-E VAFM or AFM testing specs.
Guess what? THE PINS ARE IN A DIFFERENT ORDER!!!!!!! So our 3VZE AFM Luckily(?) was still out of spec, but not as bad, 150 & 130 ohms on tests that are supposed to be 200-600 and 200-400 ohms...


3VZ-E is as follows, terminals listed left to right:
1st - FC1 / 2nd - E1 / 3rd - __* / 4th - VC / 5th - E2 / 6th - VS / 7th - THA
(*3rd position is unused/unlisted, unlike the 22RE which shows the additional terminal in it's 4th position as being VB, a designation not listed on the 3VZE AFM)

test specs are *almost* the same as the 22RE, but the terminal ordering is altered after the first two...

VS - E2 = 200-600)C (I think this is a typo for the Ohms symbol obviously)
VC - E2 = 200-400)C
THA - E2 = 2000-3000 Ohms @ 68 degrees Fahrenheit
FC - E1 = infinity ( @ closed throttle, fuel pump contacts should be open when no airflow is present)


I almost got to the point of installing and testing the new reman VAFM/AFM to see if it'd fix the degrading idle as the engine warms up, and subsequent constant stalling when pushing in the clutch once engine is 160-180 degrees or hotter. BUT... when changing the accessory belts, I found out why the ignition timing seemed to jump around when I checked spark on each cyl with a timing strobe gun, and why the ancient alternator belt had seemingly shredded so quickly - the harmonic balancer's thin rubber vibration isolation floating cushion portion had deteriorated and the pulley was just basically freewheeling on the central portion... somehow freewheeling enough to do 800 miles of towing (600 with 3 dirtbikes 3ppl and all camping/bike gear and tools, 200 towing a tow dolly and a rolling 1991 V6 R150 IFS 4WD chassis no engine, as a donor for my rusty frame '88 pickup), and still cool the radiator and charge the engine, but darnit...



This engine has been neglected for a long time and now I'm finding all the faults of it! #6 exhaust valve is at the end of it's life, maybe still functioning well enough for a while? It may just stop sealing again in 100 miles or less, throwing in the towel on this current top end. Piston rings and cylinder bores are in amazing shape via compression test and borescope inspection for 279,000 miles though... 167-176psi across 5 out of 6, 155 on #6 after running the thinnest valve shim size available - #6 exhaust valve got toasted by the EGR and lack of periodic maintenance.... This is a much better engine than the bad rap that people give it, after deleting EGR / PAIR and adding a free flowing exhaust, advancing the timing to 12 degrees so I hear, and tweaking the AFM internal spring preload settings.

Unfortunately this particular 3VZ-E does not live up to it's potential, and we are very likely ripping it out and swapping it for a VW TDI turbodiesel. a stock-ish ALH 1.9L TDI with a mild tune at first (to baby the less than stout connecting rods for now), maybe a full mechanical pump swap and no ECU, maybe a GTD1749VZ turbo and mild ECU tune... Ultimately a built BHW bottom end for 2.0L vs 1.9L and the very robust BHW/CJAA connecting rods, newer style tougher better pistons, bigger rod big end crank pins and bearings etc, and run the ALH externals and top end with a mechanical pump and a Holset HE200WG or Garrett GBC17-250 turbo and some bigger injector nozzles .220 to .240 size.
Nothing like doubling your engine torquey output AND doubling your fuel mileage while clearing up a lot of headaches by freeing up so much engine bay space!
Joe Peterson @ Doomsday Diesel is a genius and a really nice guy, and makes R150 Toyota adapters, Mercedes Benz OM617, OM602, etc adapters, and is even pushing his new OM617 replacement - V2203 Kubota tractor/industrial engines turbo'd and hopped up to hit 200-300hp goals! Lots of old Jeep guys have been doing 120hp or 130hp Kubota swaps with nearly 300lbs-ft or torque, and getting 30-40mpg... I'm definitely curious where this will go.

The ultimate goal with this Toyota was always to run a small turbodiesel swap in it though, we new that right away. The 3VZE just grew on me a little, the more I worked on it. The 22RE in the '88 pickup, I'll have some degree of guilt swapping that out for a VW TDI, but it's for the better. The 22RE is like a 3VZE that's easier to work on and has a stellar reputation, but is an I-4 of the same design as the V6, same fuel injection and engine controls etc... It'll stay in the corner of the shop for an eternity in case of future sale or future diesel fuel costs skyrocketing...