construkt

I'm not really sure what would cause what is happening right now...

Especially when I first start it up in the morning or any time its running cold, the truck has some serious vibrations when running between 1500-2500RPM. So when I'm driving down the road it will get bursts of power and then the engine will lie down a bit then do it again making me kinda jerk around in my seat constantly. Not comfortable.

This happened before and when we changed the plugs, problem solved, but it's happening again. The truck sat for a year before I got it so I'm changing the fuel filter this time to see if that could be the problem, as well as changing the plugs.

Last time we changed cap, rotor, checked all plug wires, and ran injector cleaner through with no success. There is no check engine light on which is what I would expect to see if it was an o2 sensor or bad injector running really rich.

Anyone have any idea what could be going on?

construkt

no one have any ideas? =\

chimmike

o2 sensor may not necessarily trip a code. You have to remember the car is 14 years old, and car ECU technology back then isn't 1/5 of what it is today (thanks to the more stringent emissions crap).

Check that, and I'd also check for leaks in the vac system. Especially in gaskets. Usually what happens when the motor is cold, is nothing has expanded. If you've got leaks in gaskets, when the engine warms up, it expands, and the leak is minimized, but still there.

b.miller123

I know that this may sound dumb, and I see that you said you replaced them "before"
but check your plug wires, they may have rubbed against something, or gotten burned, check the ones on the passenger side where the EGR valve and the Pair valves are, those things get plenty hot, plenty fast there is supposed to be a clip down by the exhaust manifold that holds the wires away from stuff, your's could have disappeared like mine did, I just had to use zipties to hold them out of the way

sounds like what happened to mine, but I don't think temp would have anything to do with the plug wires, but worth a look,

when this happened to me, two of the plug wires had melted, and were grounding out to one of those valves (sparky sparky!!!) , so I basically had an unbalanced 4 cylinder, vibrated like an s.o.b.

oh, and the injector cleaner you buy at the gas station doesn't do a whole lot, all that's in that stuff is alcohol, if you really think it might be the injectors, and you have the time, them pull them out and send them out to be cleaned and balanced, there are a couple places mentioned on this site, just do a search and you'll find them (and change your fuel filter too, it's like ten bucks) the cleaning will probably run you anout $100-$150 for the whole set

I'm suprised that no one here has told you to check and adjust your TPS (throttle position sensor) yet? That is what alot of people seem to think will fix everything, I'm not sure as I haven't had to yet, but do a search on that too and see if it matches what you have going on

and, yes check for vacuum leaks, that's one of the easiest things you can check

how old is the gas that's in the tank?

n4ynu1010

I had the same prblem with my '91 3.0 and it turned out to be TPS and Plug Gaps (Factory Gap on Aftermarket Plugs is not right, supposed to be .031 for 3VZE and usually are .042-.044 out of the box) , The TPS was open instead of closed at idle so the ECM didn't know it was in idle circuit and the continuous resistance connection that tells the VAFM how much throttle plate is open had bad spots all thru the range of resistance so it was surging and coming and going power wise as well , so there I mentioned the TPS hehe .
Go here :
http://personal.utulsa.edu/~nathan-buchanan/93fsm/
Look under engine (make sure you scroll down to 3VZE Motor list) and then "Emission Control Systems" for checking your egr etc. and then "MFI System Throttle Body" for your TPS settings and maintenence.
Could be alot of things , start with simple and like previous post said look hard at your ignition system as well .

construkt

Just took it to an exhaust shop. He said there is "2lbs of pressure built up in the cat" and he also said that when he opened it up it smelled really rich. So I'm thinking that the root cause of all this may just lead me back to an o2 sensor or a screwed up injector. Which leads me to another question...

Where are the o2 sensors on these trucks and are they a bitch to get out?

Thanks for the suggestions too guys, I'm looking into all this.

p.s. checked the plug wires again, they look brand new all the way through. factory wires changed in 2000 but don't seem to have any issues.

I'm changing the fuel filter as well, but for the life of me cannot get the fuel line unhooked from it. I was reefing on it pretty hard and it wouldn't come off. I got the bolt almost off and then it just stops moving. Really don't want to pay Toyota $90 to put it in for me.

construkt

I been driving the truck for about 9 months now. Before I got it, it had sat in a driveway for a year and a half. I have the new fuel filter and new factory plugs I'm going to put in since something is fouling plugs, and it sounds like changing the fuel filter is a good idea (if I can get the bastard off).

I also just found out that I need to have my driveline rebuilt. It knocks pretty hard. I will look into getting the injectors changed if need be. I'm hoping an o2 sensor is the problem because that would be a much more inexpensive repair.

n4ynu1010

If the wires are Carbon Core and they are 7 years old I would say if you mess with them often or do not have the clips to prevent them from moving then I would opt to replace them soon - thats why I prefer wire core .

construkt

They are all clipped onto the engine in multiple places on little plastic brackets. All the work that was previously done to this truck was done by the dealership and it seemed they have done a pretty good job... except for not replacing fluid in the rear dif which in turn blew it out and I had to replace it.

Luckily this truck had 1 previous owner who is my father's friend so we have a record of all work done on the truck. The differential cost came out of my pocket though, as it was a dealership quite aways away and it was worked on a couple months before the truck was permanently parked, that is until I bought it.

So far, the truck has needed the following things:

new cap
new rotor
new rear differential
new clutch
new plugs twice now
new air filter

needs:

new cat-back exhaust system
needs driveline rebuilt
probably needs new o2 sensor or injector

I guess thats what I get for paying $3000 for a truck with 165k miles on it. I get what I pay for.
fine tuning on the TPS

n4ynu1010

If your going through plugs that fast for whatever reason I think I would find the reason why they are fouling so fast

b.miller123

I second the notion about the plugs, figure out what is causing them to get fouled, then go from there (and almost everyone on here is in agreement that the factory (i think they are denso) plugs are best, which you have already )

as for the fuel filter, I haven't changed mine yet (it's on the to-do list) so I can't help you much there, I'm assuming that you've already tried soaking it with WD-40 or whatever before you try and take it off, as you said you were able to loosen it, maybe someone else will chime in on that

as for the O2 sensor, it's right before the cat, and make sure that you soak it with Wd-40 or Pb blaster or something like that, do it a couple times a day for a few days before you try and pull it out (and yes it will probably still be a bitch) oh, and O2 sensors are a lot like lightbulbs, they go bad slowly over time and will need replacing way before they trip a CEL

that sucks about the rear diff, there was a guy on here that had a bunch of complete e-locker tacoma rear ends for like $700, but that was a while ago

construkt

ahhhh holy crap, I would have my pants for one of those rear ends. I paid toyota $1000 just to deal with it because I had no room to tear out a dif.

I think the problem was the o2 sensor because I pulled all plugs and it looked like it was running a little rich on them. Then I pulled out the #3 cylinder's plug and the ceramic insulator around the filament was CRACKED. I have no idea what would detonate a spark plug like that unless it was already trashed or the gap setting was way off (which it wasn't). So those are in, we managed to get the fuel filter it, turns out you just have to really crank that bitch from start to finish to get it back on. Feels like you're crossthreading it, but you're not, I guess thats why the dealership told me to be really careful.

I also went down to NAPA and picked up a Bosch universal o2 sensor. I know its not the favored one, and I had to jimmy rig it up to the old connector but it seems to work fine. Right now the truck is running great but I need to get my driveline rebuilt so I am going to check out a few places to get that done today and then all that is left to do is the exhaust and pick up a K&N cool air intake. It's going to be a long road with this truck I can tell already.

n4ynu1010

You know if you read some of the posts and the links given for the K&N they don't recommend it because it lets alot of dirt through that the stock filter doesn't and the Air Flow Test's they have done show very little air flow improvement and on top of all that there are posts that make a very good point that unless you are picking that air up outside of engine compartment (which stock box already is) that you will pick up more hot air than you already are

Do a search and check it out , I was thinking the same thing but opted not to after much research , although the ISR (new air tube) and the removal of the resonator does have some advantages and then you can insulate the air tube as well and save yourself some intake temp using the stock box .

b.miller123

X2, my truck came with a K&N (just the filter, not the "intake" thingy, which besides not doing you any good, is totally not worth the $$$) from the previous owner, and whenever I get around to it, I am going to put a stock filter back in,
the $200 minimum that the intake thingy is going cost is better spent else-where: new timing belt, tune up, stereo, hell thats an optima battery and some $$$

Another bad thing about the K&N filters: the filter oil
It's really, really easy to over oil the filters when you clean them, and they could possibly be over oiled when you buy them new, and all of that oil is going right onto your mass air flow sensor, and it'll get dirty quicker than a mud wrestling stripper!

Some people might think that it is a fair trade-off, being carefull, in return for a louder intake sound (which is all your going to get), and maybe some "seat-of-the-pants" power increase, which probably didn't even happen anyways. I believe that anyone who thinks they got more power (enough to "feel" while driving anyways) from a "cold air intake" is an idiot, they are probably just stomping the gas more so they can hear how much "better" thier intake sounds, and they think thier truck got faster because they don't normally stomp the gas at every launch, when all it's doing is sucking in the same amount of air, only it's hotter and is louder because it's not enclosed in an airbox.

And anyone who wants to debate this, be my guest. but unless you have actual footage of a before and after of a car running on a dyno with the hood closed, then don't bother

n4ynu1010

Yeah what he said

b.miller123

Yep, I break it down Barney-Style

construkt- did you ever figure it out? we're we any help?

n4ynu1010

Don't ya mean "Blarney" - the evil Barney hehe