Issues with a '92 (and HELLO!)

Skullduggery

Skullduggery

New member
Hello everyone!

I am new to the forum and to the 4Runner as well. I just picked up a 1992 in pretty good shape from a neighbor, it has two flats and some issue when running.

At around 3000 to 3500 it seems to run rather crappy. Idle it runs great, you would not assume that there are any issues at all.

The last owner gave up on it and now it is mine to trouble shoot.

He had thought that it was the injectors, but I think that it is the fuel filter. As he re-wired the injectors and did no good at all.

I can see that some time in the past (as the gaurd is not on the filter) the filter was replaced. He tells me that he did not replace it.

Any thoughts? I think that something that is about $20.00 is a good place to start with the trouble shooting...

It does have an exhaust leak, but I do not think that is the cause, but it will be fixed shortly.

It is 3.0 ltr, 4wd and Auto. I think that is all you would need, but if you have any other questions, please ask...

Any thoughts are great!

Happy to find the site, and will be here often.

Thanks all...
 
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As a starter, unless you know the servicing history on the 4runner I would start with simple stuff. Fuel filter, plugs, wires, ect. Don't jump to replacing them, just inspect them. If they look old or ugly, then replace them. But I doubt your troubles are coming from them. Maybe someone with more knowledge on the 3.0 motors will chime in but I would recommend you download the FSM on the top of the forum and read through it.

From my experience, if you're having issues at a higher RPM then I would look more towards the throttle position sensor or the AFM. They seem to be common issues on these older toyotas. If you have a multimeter, there are steps in the FSM on how to test each of these components and other various sensors.
 
Id start with checking to see that the TPS and AMF are in spec. Download the Factory service manual from the link on the top of the classic forum.

Besides that I would start with plugs and wires. Check all vacuum lines and possibly throw a bottle of sea foam at it. (search, there are a few thread here about seafoam)


Good luck and welcome to the forum!.
 
I should have stated this before, but here it is now...

He replaced the wires (plug) and the dist cap, rotor, Air Filter, and plugs. He also replaced the wiring for the injectors. He ran Seafoam thru as well. I have been checking the vac lines, there are a TON of them!

I just grabed the manual and will take a look at it. Any section I should look at?

What is the AMF?

Thanks All!
 
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I'm pretty sure he meant the AFM (Air Flow Meter).

I would start with the EFI section. It will have all the necessary steps for troubleshooting your issue.
 
Still working on it...

Bought a fuel filter today, will try to put it on and see what we get with that addition.

Keep the suggestions coming please...

Thanks
 
Fuel Filter Replaced today

I replaced the fuel filter today and sadly that was not the issue, but was a MAJOR PITA to do.

Not sure where to go from here, any ideas from you guys would help a bunch.

As it seems to be fine at idle and does not start to fail until about 3K, and at that point stutters runs rough, I am not sure where to go. It looks to be fuel related, but I could be wrong I guess.

If you have any ideas, please let me know.

Thanks
Randy
 
Any thought at hooking up a timing light and just seeing if the timing goes weird at the problem engine speed? I have a '91 with the 3.0 3VZ motor that we bought new and have enjoyed working on it. Yes, there are a lot of vaccume lines! The manual is really good with test for most of the sensors (as you have done).

When it runs crappy does it backfire or spit, or just seem to miss-fire? Does it run crappy when you manually rev it to 3-3.5K or just when you are driving it?

Being that I have a '91 maybe we can compare notes.

Randy
 
Yea, I did the timing light trick and it is fine, no issues.

It does cough a bit when you gas it up, but no backfire, not sure how to explain it. It is not every time, but most of the time it does.

It runs great until you hit the just above the 3K mark, then it is crap.
 
A picture being worth 1,000 words then a video is .... An Excellent Idea! I recognize your engine.... looks just like mine!

If the timing light shows no glitches or unusual behavior at the problem rpms then I think you are looking at a fuel issue. I do have this nagging thought in the back of my mind that if someone replaced the timing belt and didn’t get it put back together with all the mechanical timing marks in their correct association then the engine would idle fine but the computer would not be able to compensate for correct timing advance with rpm and the timing light would not show the error… as it would be very hard to know where the timing should be at 3-3.5K rpms. It would be a lot of work to check the mechanical timing. As I mentioned, we have had our 4Runner since new and it IS a vehicle worth investing time and money into as they are well built and can be kept road worthy for a very long time.

I had a VW TDI that exhibited the near-exact same symptoms and the problem turned out to be the Air Flow Meter. The tests in my service manuals for the Air Flow Meter are static and pass/fail; they do not test it for linear response over an rpm range. My primary service manual is a Chiltons and I have the factory wiring diagram manual as well. And they both show the same pass/fail test for the AFM. I tested my AFM yesterday as I am troubleshooting a fast-idle issue on our '91.

Another idea... If the Throttle Position Sensor" has a dead-spot I wonder if it could produce a similar symptom? The TPS can be rotated within a range. If it had a "dead spot" and you try rotated it such that it would be at a different mechanical position at a given throttle opening; might be worth a test/try and wouldn't cost you any parts. You would just need to reset its idle setting adjustment when you’re done.

I replaced my EFI water temp sensor yesterday and was talking with local parts house and they indicated that the EFI Water Temp Sensor, Air Flow Meter, and Throttle Position Sensor are all commonly stocked parts; indicating they fail often enough for them to keep inventory on-hand.

Too bad you don't have another 3VZ motor nearby that you could swap parts with for troubleshooting. That is how we isolated the problem on the VW TDI.

When you get above the problem rpm does it smooth out?

My comments come from my experience working on our '91. I come from a family of mechanics but am not a mechanic myself. I've found a lot of good help on this forum and I am hoping others with more knowledge/experience can jump-in and help you isolate the source of this problem.

Randy
CdA, Idaho
 
I had another thought.... if you think that the problem is fuel related what if you squirted some starter fluid or carb cleaner into the intake side of the throttle body when the engine is at its problem rpm. There is that tube on the intake side of the throttle body which feeds back into the engine the oil fog/blow-by gases. You would need to plug the hole after removing the tube but you could inject your starter fluid there and see if the engine changes symptoms at the problem rpm with the fluid added.

Randy
 
Thanks

As I agree they are worth the time and effort. Funny thing is, the engine is VERY clean, looks like it was swapped out, I have no way of knowing as I bought it from the previous owner, he bought it and tried to fix it, but failed to. I have no idea who the last owner is, or if they were the ones that did work on the truck or maybe they bought it this way as well.

I guess I could pull the covers off to check the timing belt and make sure that it is set up correctly, should not be a big deal to do. (LOL)

I have a long history of VW and non FI engines, but I am no expert for sure. Been trying to get a friend who is and "Expert" to come over, but he has lots of issues with getting here with work and family (I am 30 miles away), so I understand and keep trying.

So, I will take a look at two things then...

1. Timing belt install and make sure it is as it should be.

2. Check the timing light again and make sure there are not issues with it.

In regaurds to number 2, what should I look for in the test? What else could I do in this test?

Thanks
Randy
 
I will check into the fuel, but it was empty when I got it. I had to get fuel when I picked it up. I also ran that fuel out (in the drive running it) and added some additional fuel. So I don't think that it is fuel, but it does not smell normal, so I will give it a shot, what the heck...

When I first fired it up, we were using eather (starting fuel) and it did the same thing, so I think that is what I will find, but I will give it a shot.

Thanks again...
 
Okay, I did the timing and it was off a bit, maybe 5 deg or so. It runs better, but still the same issue, here is the video of the issue now.

I also did the test with starting fluid to test the fuel. It acted the same with the starting fuel as with regular gas, so no change there.

After timing adjustment - YouTube
 
Your Videos are great!

What I meant by fuel-related was not so much the quality of the gas in the tank/system but whether or not the engine was starving or flooding with fuel. My dad used to say that an engine needs three things to run - compression, fuel, and spark. If it was running poorly due to fuel (either too much or too little) then adding the ether should have changed the symptom... and it didn't. I am understanding this right by spraying ether into the throttle valve you would add combustable vapor to all 6 cylinders irregardless of the injectors, airflow sensor, etc.

Regarding the timing & timing belt, you have the relationship of the crank and each of the two overhead cams. All three have to be perfectly in sync (I only know this from having changed the timing belt twice on our '91). If one of the cams was off a tooth or so is it possible that it could idle correctly and yet cause this symptom with increased rpms? I don't think this error would show on the timing light.

In my thinking.... if you have compression & spark and the symptom doesn't change by adding ether then next place to check/verify would be mechanical timing. The problem with this is things aren't that simple. The fuel and spark are modified by the computer which accepts input from a half-a-dozen sensors.

We need more input from others with more experience. I think if I were in your shoes I would verify good compression, and next replace/inspect the timing belt. I am guessing you don't know when the last time was that it was changed, which makes an inspection/change a good idea even if the motor was running correctly.

Randy
 
As I stated in my first response... I'm not very smart on the 3.0's but it sounds like your motor runs great until you get to a higher rpm.

Have you checked for vacuum leaks? Check out your vacuum diagram and use that as a reference to make sure you're checking all the vacuum lines. A vacuum leak could cause that and I think it's a pretty simple thing to check.
 
All good points and I agree. Would love some additional input as well. I am willing to do what ever is suggested to get to the bottom of the issue. As you hear in the video, it runs great up to the poing of about 3K, then it craps out like it is starving.

I had thought ( from past experiance) that this was the fuel filter being plugged. I bought and installed a new one, but that did not do the trick.

You talked about another 4runner close by, there is one that is not healthy down the street, have to stop and introduce myself and see if I can use a part or two from it. Not sure how that will go, but I will offer to help him as well. If that fails, there is a "Pick a Part" auto salvage not far from here and I will go start grabing parts.

I think that tomorrow I will clean the AFM and test it, could not hurt to do that. We will see what we have from there.

Thanks you for the help, and keep it up, a sounding board is good also. Just to have some one to bounce ideas off of is a good thing too.

Thanks again,
Randy
 
SV Dude,

Need to find the vacume gauge (or go buy a new one at Harbor Freight) to do some testing.

It is an odd problem for sure, now that you guys can hear it run it makes it a bit easier for you to understand what I am looking at here.

I will do the other tests I mentioned above and see what I can do about vacumme tests too. I think autozone lends tools too, might check there as well.

We will see how it goes tomorrow, thanks again for all the help guys, mostly confirming what I had thought, but I have no one here to help me or to bounce things off of, and that makes it toughter for me.

I can do just about anything, but it is nice to have a few ears and eyes to get though the tough stuff with me...

Thanks again.

Randy
 
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