Timing oscilates 3 deg. on 92 3VZE

[NerdNoise]

So when I set my timing, I connect the little paper clip and start clicking away with the timing light. The little mark on the crank pulley will oscillate about 3 degrees towards BTDC (8 deg +3 deg) back and fourth, just kind of bounce around in there.

I looked at the timing on my 80 series 1FZ-FE and the little mark is solid and does not budge at all.

Any ideas?

 

[bryan89]

i assume this is at idle? no racing of throttle?

i have the 22re so you will have to bear with me on this...but,
here is what i would suspect.
on the 22re the timing mark is on the crank pulley. the pulley itself is part of the harmonic balancer and is only held on with a press fit rubber seal. so i would suspect that the 3vz is the same.

if so, what could be happening is that your most likely original crank pulley has finally s***e the bed. what happens is the rubber balancer part dries up and becomes brittle. then under the torque of the motor and belt assembly the pulley can actually "walk" around the balancer portion. this would give you the appearance of the timing marks "moving" even though the engine remains timed.

pull the pulley off and you can see it. if you cant see it right off, look at the orientation of the key way for the crank and the timing mark and see if it is correct. for example, on the 22re, they should line up. if it has walked...it wont. also another safe bet is if the engine sounds fine the whole time the mark is moving, its probably just the mark shifting around the crank pulley.

so i would start there. it is a likely source.

on the other hand, if your timing is actually changing (not just the illusion of changing) then your symptoms might include:
worn/stretched timing belt
worn/non functioning tensioner

 

[2ndGenToyotaFan]

Most Toys that I've timed have had a little bit of wandering going on. If it's running fine and the timing is staying where it should, and it's not wandering outside it's 3 degree range, then I would not worry too much.

If you think about it, your timing mark is on your crank pulley, which is on the harmonic balancer, which is attached to your crank, which is attached to the timing gear, which is attached to the timing belt, cam sprocket, cam shaft, distributor sprocket, dist shaft, dist rotor..... There's a lot of room for slop in that system...

 

[NorCalBorn]

^That, mine does it, but not what I would consider wildly, it's always been like that even when it was my customer's rig w/ only 4000mi on it. Run the throttle at 2000rpm's for like 20 seconds to clear things out and get the ECU into a set mode and then set your idle to spec. Then go back and adjust the dizzy. May take a couple of shots to get it closer.

 

[bryan89]

idk guys,
mine is dead nuts every time. when i built the motor and buttoned up the distributor, i guessed at where i thought "perfect" would be. it fired up the first time, it was on, dead nuts. havent moved it since.

while i agree there is some "slop" in the timing system with backlash of all the gears and chain and what not, when the system is in motion, all of that goes away. meaning, once it starts spinning, the slop comes out and the gears are loaded in one direction the whole time its spinning. so it should be consistent unless you unload the gearset and change directions of rotation. (which is really bad in the sense of an engine lol)

i dont know if that explanation was clear, but my point is whether the timing is right or wrong from what you read, it should be the same every time the engine comes around.
imagine if you had two gears in a mesh. if you hold one still and try to spin the other one it will "jiggle" back and forth in the space between teeth. this is the backlash. once you let go of the gear and it starts to spin the backlash effective comes out of the system. one tooth makes contact to push the gear and before it rotates out of the way the next tooth makes contact. so as long as its under a spinning load, the second gear should have no "wiggle". if you do, either something is really worn, or you have the wrong size gear for the mesh (in a theoretical sense, not actually on your truck nerdnoise. just an example)

thats just my opinion

 

[NerdNoise]

Well although your observations are the most pessimistic so far they seem pretty plausible. If Mythbusters has taught me anything, it's that plausible is 99% confirmed. So, what are we thinking? Mechanical ( worn cam lobe on one cylinder), retarded injector, electrical? Maybe the worn balancer is the cheapest and easiest place to begin. Also, I do notice a bit of " turbo lag " so there is something going on with timing and advancing.

Sent from my C771 using IH8MUD

 

[bryan89]

yeah, i would start with the easy stuff first. check the crank pulley. then go from there.

i dont think a worn cam lobe or retarted injector could change the timing. a worn lobe would just cause the valve to not open as far, or at all. so it would run crappy but remain timed. an injector problem would cause it to run crappy too.

just be glad it hasnt flung itself into a million bajillion metal flakes and you can still repair it relatively cheaply if you find out what it is. (how is that for a positive outlook...huh huh??

 

[NorCalBorn]

Timing oscilates 3 deg. on 92 3VZE

I do notice a bit of " turbo lag " so there is something going on with timing and advancing.

OK, I'm lost here. 3VZE doesn't have a turbo, those HG's are iff'y as it is. Clarify please.

 

[NerdNoise]

No turbo; that's why I placed 'turbo lag' in quotes. Basically what happens is that the motor comes alive at about 3000 rpm (estimate). If I get on the throttle, it moves along until I get to about 3k rpm and then, wham! The motor really comes alive. The power curve seems logarithmic vs. linear (hence the term turbo lag).

That's why I'm thinking something is going on with the advance. Based upon the above mentioned symptoms it seems like I'm stuck advanced and when I get to the RPM where I normally would advance, it ignition is already there so the motor comes alive. Is this making sense? My wife always tells me that brevity is not my strongest trait.

 

[ToyotaDon]

Test your throttle position sensor, including the idle switch circuit.

When you're checking the timing, does blipping the throttle cause a large jump in timing? It should, if your TPS Idle Switch is working properly/properly adjusted.

If the ECU thinks you are off-idle, it will continue to control the timing, even with the paper clip in place. When this happens, you set the timing too low, and that is where you get the lack of power.

HTH