jloewenheim

First time logging in and hoping that someone out there might be able to give me a bit of insight as to what i might be encountering. Sorry for such a long entry, but I figured i better lay out all the details here.

I have a 94 4runner with a 3vze engine. For about a year, the engine was giving me trouble that felt like a miss. During this time, no trouble codes were occurring, no issues of oil in coolant/coolant in oil. The only real symptoms were a rough run, lack of power under load, and if driving for a long time at highway speeds, the temp on the trans (unfortunately an auto-pain in the rear during the reinstall) would get very hot.

I will qualify this by stating that i am not an expert, but at the same time have a fairly extensive amount of mechanical expertise.

While this was going on, I didn't have a facility to do extensive work, nor the time to tear deep into the engine. As much as I hated to do it, the runner wound up at the dealer to fix the problem (talked to a few mechanics who said they were not sure they could beat the pricing i would get at the dealer). Six injectors later, a new fuel pressure regulator, and some overall troubleshooting, I get the runner back (and my wallet $1000 lighter). Still wasn't running right, frustrated but not really having the time to deal with this, i took a break from driving it. My GF started to use it from time to time to drive the dogs places and runs to HomeDepot, but other than that, it didn't get a ton of use under massive strain. Then one day the miss started to get bad and some smoke started to come from the tail pipe. Before i knew it, the head gasket was blown.

Head gasket had already been replaced at 50,000 or so as a dealer recall, at this point there were about 70,000 on the motor. My guess is that this miss under-load at highway speed is what caused the head gasket to go. Fair enough, I figured that it was time to tear into the motor and replace the head gasket. As I get into it more and more, i realized that I might as well replace the engine.

The remaining portions of the block were removed and I started to do my research for a rebuild. Somewhere in there I came across a place in Denver that sells 3 year warranted rebuilt engines for about what it was gonna cost for machine work and the replacement parts. I talked to my friends at the machine shop (yes I have rebuilt a few engines before-never needed to with a toyota) and they said i was better off going with the rebuilt due to the warranty.

Engine was purchased, delivered a few days later, and I could not have been happier.

As luck would have it, a buddy of mine now had a lift in his garage, so it was time to get the runner running again. He couldn't wait to use his lift for something like this.

Long story longer....

Engine is installed, i button everything up including brand new injectors and spark plugs. New battery installed, crank the engine for a minute or so with the main dist wire disconnected (want some oil to pump through the engine before the start), connect the wire and it fires right up.

I let it run for a bit, set the timing (jumped the leads as stated in the service manuals), and notice that it still isn't running all that great. That same miss that was going on before the head gasket blew seems to still be there. Also, there is a quite a bit of smoke coming out of the exhaust that shouldn't be there. After scratching my head a bit, I figured I better start digging through some of the internet info and reading both my factory service and haynes manual.

After copious amounts of reading, I am starting to think that maybe the issue is a TPS thing (Bill Lumberg wasn't sure that I got the memo), for all i knew, this was the same TPS it had 14 years ago. Apparently this is a common issue on toyota engines of this vintage according to many of the postings.

Time to go check things out again, first thing i do is disconnect the connector to the TPS hoping this was it, but no luck. So I went back to the tried and true stuff that my dad would have gone over with me on the old points distributor cars we used to rebuild and play around with. It was time to start disconnecting plug wires. Sure enough, I disconnect cylinder 2, the smoke is gone, engine is running pretty strong (isn't running on 6 cylinders, but is running better than when the 6 wires were hooked up).

So now I am a bit stumped. What I do know is that if it is missing on cylinder 2, and running significantly better once the wire is removed, ignition isn't quite right in there. Could be a valve issue, but I cannot imagine that anything could be wrong with that outside of potentially an improperly installed shim causing the exhaust valve to seat improperly. More likely in my head is that there is a problem with fuel delivery to that cylinder. Since this problem existed before (i should have done the plug wire test before the head gasket blew to verify that it is exactly the same problem) and it is a rebuilt engine from a highly reliable source, I don't think that is the issue.

Since it is a brand new injector and all other cylinders seem to be working fine, I am thinking that the wiring to that injector is not functioning properly. So my questions then become, what times the pulsing of that injector, and is there an easy way to determine if that injector's harness is not working properly?

Any help you guys could give is greatly appreciated.

Thanks

Jake

idanity

i share your pain (bought a 3vz and blew a head gasket)..(and please, pm me the place that sells rebuilt motors- and delivers)

i have some smoke, that comes from my engine too, but its very strong.

i am not sure about much (im at work now) but injectors can be stuck closed or open, i would 1st get a spray test done on #2's injector to ensure its integrity...

hoipe that helps

jloewenheim

I am starting to think/hope that maybe this is a computer issue. I am fairly sure that there is not an issue with the injector itself, more likely with the wiring to the injector. My next step is to pull the harness off the injector in cylinder 2 and hook a test light up to it. While I am at it, I will check all 3 injector harnesses on that side of the engine. Maybe there will be a difference in voltage or something that shows cyl 2 is not getting the correct pulse. Where to go from there, I am not sure. If I am lucky, all I will need to do is get a replacement ECU and put it in the kick panel.

To get that engine, go here http://www.toyotacarpart.com/default.asp?c=3

These guys are pretty knowledgeable, I am planning to call them tomorrow and see if they have some ideas for me.

Jake

abecedarian

anything in particular from keeping you from moving injectors around, maybe that #2 to #4, then #4 to #1 and #1 to #5 and #5 to #2? I suggest the round-robin swap just to randomize things even further- just track where the theorized bad injector ends up.

jloewenheim

I like your thought process and nothing would keep me from doing this. My only hesitation to doing this is that all 6 injectors are brand new and a similar problem (though i didn't confirm it with removing the plug wires prior to replacement) existed before my replacement of things. That being said, I am sure that I will do this as I test out the harnesses on cylinders 4 and 6 also (easy access to these without removing the entire plenum).

I would love to know what tells each injector to fire. ie it would be nice if there was something in the distributor that maybe could easily be replaced. I kind of doubt this though, I am guessing it is more likely that the ECU decideds this based on RPM and MAP/TPS/O2 sensors.

DWok

I think that the computer is ok, I beleive that there is only two injector drivers in the computer that drives the injectors as bank 1 and bank 2 so if cylinder #4 and #6 are working they are on the same bank as injector #2 and further down the harness as well. get a noid light from local parts store and check operation if you still suspect a problem. Also one of the wires to the injector should have full voltage with key on all the time and the computer supplies the ground to drive the injector on the other wire.
I recommend checking ignition wires for correct placement on cap first, their could be two wires crossed very easily.

jloewenheim

Thanks for the input. Although I wish it were, I am positive that it isn't a crossed wire issue. Aside from using toyota dist cap and wires which are labeled, i have also checked this a few times as part of my pulling plug wires thing.

I will see what comes of the testing leads on the injector harness. If I am lucky, the harness is bad, and I just grab one from a salvage yard or ebay. I do not have confirmations that cylinder 4 and 6 injectors are firing, but pulling their plug wires did not fix the miss and smoke out of the tail pipe. Interestingly enough, pulling their plug wires in conjunction with pulling the #2 wire didn't seem to have much of an effect. Maybe the bank that controls that side is off.

Just means i have more testing to do.

Thanks again

b4wheeler

iTrader: (1)

Keep us updated on what you find. My 3vze in my 88 4Runner just started having a misfire problem.
Weird thing about mine is that the miss will come and go.
I have located the dead cylinder and already changed the plug wire. I am thinking Injector or wiring harness, right now.....

DWok

when checking the wiring the Black/Red is a constant power from the ignition switch to all six injectors and the White is the ground supplied by the computer for injectors #2 #4 #6 and white/Red for cylinders #1 #3 #5.
When I rebuilt my 91 a year ago I found that I had to run more ignition timming than the spec called for to get best results almost 20 degrees, you can confirm this with a vacume guage when setting the timming and shorting the terminals at diagnostic connector and get the highest reading on the guage. this may help

jloewenheim

Thanks, I talked with the guys who sold me the engine yesterday. They said from their tech standpoint it would be best to do first a compression test, then try to run the engine with the harness for the injector disconnected, finally finish with a sniffer test (emissions diagnosis). Sounded like sound advice to me, a compression test will be done then the rest.

If I am lucky, I will be able to figure out something that is a simple repair. Maybe it is as simple as my computer being jacked up (this is expensive, but doesn't really require much in the way of labor to replace).

Someone mentioned a blade tester that can be hooked up to see the injector pulse. Not really familiar with that tool, anyone have a link as to what one is?

Thanks again

Jake

mmcpeck

I think that is what was suggested above, it is called a noid light. It is a small light that plugs into the injector harness, and will light as it gets the ground pulse from the ECM, basically you can see how the injector would be pulsing and check the duty cycle.

I think you can get them at any auto part store or look around online. If that is what you meant by a "blade tester", not sure.

Good luck, definitely keep posted as I have the same motor with 200K on it and am always interested to see what I will inevitably have to fix. I have a small little hesitation right after I first start up and first put into Drive and go, it stutters for a split second then picks up and pulls pretty good, as good as the 3slow can.

I also have the classic idling in gear at 500 and shaking, but then at the next light it will be idling in gear at 700. TPS may need cleaning or replacing, it is an original '91 so it's 17 years old.

Anyway good luck, hope you get it figured out easy enough.

jloewenheim

Thanks, I really appreciate the advice, will keep you informed as to how things are progressing.

jloewenheim

I think I will probably hook an oscilloscope up to the 3 harnesses for the EFI on the driver's side of the engine and compare them. My guess will be that the pulse going to cyl 2 will not match that of the others, but we shall see.

abecedarian

one thing throwing me off on this is your mention of smoke that went away when you disconnect the #2 plug. there should be no smoke at all.
tell me more about the smoke- white, bluish-gray, black? did it have an odor?
but I think the engine supplier is correct in suggesting a compression test.

jloewenheim

A quick update, compression in the cylinder (As I had assumed) turns out to be fine. A call back to the shop where the engine came from and their tech expertise said that it is probably time to do a tailpipe analysis. Makes sense, the issue is either a bad spark, or a bad fuel mix. The tailpipe analysis will definitely monitor the burn coming out. Whether it is rich, lean, or just poorly timed (the spark or fuel pulse); I am certain that this will not be an easy fix unless it is as simple as me replacing the computer.

Very odd, no trouble codes are present, so it is a little tough to say.

In response to the last question regarding the smoke, it is white, nothing that will immediately point to oil in the cylinders, bad valve guides, or a blown gasket. There definitely is fuel getting to the cylinder, when i pulled the plug after running it disconnected, the plug was wet and smelled of gas.

jloewenheim

Well, it has been a long time since i have posted on here, but today got around to doing some more testing. Turns out that my friend who has the garage where I did the engine swap remembered that he has a Snap on Vantage hand-held meter. We started to play around with things and the first thing that I wanted to check was the fuel injector pulse.

Pulse for cylinder 2 turned out to be fine. We then started to check the spark plug power level. One thing is for sure, cylinders 4 and 6 are not getting much in the way of spark. Before I do anything else, i will pull all 6 plugs and regap them.

Regardless, it still does not explain why I am getting a misfire when the #2 spark plug wire and injector harness are connected, and then it smooths out when either are disconnected. Yes the power level goes down, but the tailpipe smoke disappears and so does the miss.

Still looking for some clues.

ahickman

Any updates on your progress?

truckmike26

A rebuilt long block and white smoke. Maybe a cracked/warpped/leaking intake manifold. Upper and/or lower plenum leaking coolant? I just posted something relating to how I had a bunch of trouble with all the coolant transfer hoses and pipes that snake in and around the intake and throttle body.