[Option78]

Hey there,
I have an 87 4runner with 22re and 318K on the dial. Currently having issues with the motor and I am not sure how to proceed with fixing it up. To make it easier to describe I have taken a few videos...




So basically how this all went down... I had been noticing some slight jumpiness when accelerating in first gear, just seemed like it didn't want to accelerate easily (but otherwise drove no problem). I was driving and suddenly it lurched and shut down. I pulled over and get it fired back up but it would NOT take a load. The second I actually tried accelerating it lurches and bucks like crazy. Towed it home.

What I have discovered is that the engine doe not seem to have any issues when I first fire it up (aka when cold). I can throttle up to 2-3K and hold it without it losing power. However, once its been running for a minute or two the problems arise. Trying to hold the throttle steady (as seen in the videos) it will come up to RPM and then dramatically fall off (without dying, i noticed).

So thus far I have replaced the fuel filter and that is more or less it. I hate throwing parts at a problem but I am one step away from taking this thing in to a mechanic (first time ever in a decade of ownership!) I just don't know exactly where to start and the internet has led me on a vast vortex of sensor checks, fuel pumps, etc. etc.

Any help would be appreciated!
Thanks yall

2ToyGuy

When it died, did you get a Check Engine Light (CEL)? Have you checked for any stored CEL codes, using the test jumper?
You should remember to clear out all the old codes first, by pulling the EFI fuse, IIRC, for at lest 30 seconds. You can also pull the negative battery lead(s) to accomplish the same task. You don't want to chase an old code that has nothing to do with the current troubles.
Then duplicate the trouble, shut it down, and read out what code(s) show up now. Always a good starting point. Gives you a place to look for what might be causing your troubles. Could it be fuel pressure, or flow volume? Timing off? AFM readings bad? Throttle Position Sensor bad, or in need of adjustment?
See what I mean? There's a lot of things it MIGHT be. The CEL codes can give you a place to start looking. What system might be involved.

Is this any help?
Pat☺

[Option78]

So no CEL is present so no codes to find. Your list of options definitely describes how I’m feeling about tracking this thing down, lol

I’ll double check the timing when I get the chance

millball

There can be stored codes, even when no check engine light is currently illuminated.

[Option78]

Got it! I will clear the codes as well! Thanks

5 Fists

Does it idle high on cold start up? Maybe the Idle Air Control Valve is not functioning properly, or is not set right? It won't actually stall out you said, but maybe it's dropping the RPMs so low it that it runs rough once up to operating temp? Is your idle set right? If you're going to throw the jumper in to check timing, might as well check your idle is set correctly as well.

Co_94_PU

iTrader: (-1)

Let's be clear here. You want to read the codes before you reset them, and write them down, then see which ones reset when you start it back up.

I see in the video abit more movement in the engine than I would like but that might be the camera operator, which leads to the question "Hey bro how are your engine mounts?" Which seems like a strange question to start with to some but the thing is there isn't a lot of slack in the engine harness. It's not super important at this point but always something to keep in mind once the engine starts misfiring and moving around alot.

We can't see in the videos if you are holding the throttle open to keep it running or if it is at idle on its own and then falls on its face.

... Back on track maybe ..

You mentioned it runs fine for a minute or so. I assume this is a cold start? This is a clue that it has a sensor discrepancy because on a first start up its in what's called "Warm up enrichment" mode where it feeds extra fuel via the injector pulse length and ignores all the sensors except the throttle angle.

There are some pretty disturbing sounds going on in this that give me the metal on metal feeling. It's probably worth the time to pull the valve cover off and verify your timing chain didn't jump (Timing mark at zero, cam dowel straight up at 12, and number one valves both closed)

tstockma

Vacuum leak in the intake system? Stumbling & low power can definitely come from that. Leaks can act oddly with different vacuum levels in the hose (or wherever the leak is) causes a crack to close up & seal...or widen & suck air...if I remember right, a shadetree mechanic technique is spray penetrating or light lubricating oil on some of those vacuum hoses & other spots, if suddenly it runs better while spray is being sucked in along with air, you've perhaps found the spot. Seals, o-rings, gaskets as well as vacuum hoses are where this can happen. Sometimes the leak will be in "control hoses" which have vacuum, are not direct intake into the air/fuel system, but instead might drive sensors & the emission controls. The spray oil sometimes will plug something up for a few seconds or longer, even in a control system when it's not direct intake into combustion.

Melrose 4r

Spray water instead... same effect, no mess.

[Option78]

A couple of clarifications here. In the videos I am almost always keeping the throttle steady, the motor is doing all of the changes in RPM on its own. The vehicle never threw a CEL when the initial event occurred and still does not present with a CEL. If I can get my hands on a scanning tool I will take a look at what is stored in the computer BEFORE reseting it.

2ToyGUy, I was wondering the same thing about Fuel Pressure and I can imagine how after running at higher RPM for a few seconds leads it to not having enough fuel, but it doesn't necessarily explain why the motor doesnt have issue until its warm. It seems like it should have the same problem when its cold too (which doesn't seem to be the case). BUT I would love to find a way to check the fuel pressure at home.

5 Fists - it does not seem to idle high at cold start. In fact, it starts right up like it always had and I see no differences in the way it acts. When I check the timing I will check my idle, but it does seem to be all good there.

CO_94_PU - Got it, read the codes, THEN clear them, then see if new ones pop up. Thanks for the clarification. Engine mounts! Okay I will check these out, i just did a trans rebuild and didn't notice anything on inspection but obviously I was more worried about the trans. In the video, the motor is falling on its own, I am just holding the throttle steady, sorry for the confusion there. You're SPOT ON in regards to it seems to be fine when the computer isn't using the sensors. Once it warms up it seems to have issues. So a sensor discrepancy is where my mind is going as well. On a more serious topic, you think you can hear some bad stuff going on in there?? That is concerning. I did the timing chain myself about ten years ago (about 40,000 miles ago) but I had not thought about this. I would hate to ruin this motor. I will definitely do a double check on the timing here when I get the chance.

Moving forward - I feel like this is a sensor issue (not guaranteed), does anyone have an excellent source on which sensors I should be looking at and how to check them out? I do have a FSM that may explain some stuff but I don't have a full collection of tools (just a basic voltmeter).

Thanks a ton y'all!!

scope103

The scan tool you need can be kinda pricey. https://www.staples.com/Gem-Clips-Gi...product_633858 [ ;^) ]

Your FSM should have the procedure for checking the codes. This should be it for your vintage rig: https://www.4crawler.com/4x4/CheapTr....shtml#Reading You probably already have the $0.03 scan "tool."

[Option78]

So the final result, for anyone that is experiencing similar symptoms.

I had an exhaust system blockage! My Catalytic converter had broken apart and jammed up the the pipe between it and the muffler. Back pressure in the system was preventing the motor from functioning at higher RPMs. And to clarify any confusion. The videos I posted were all of me holding the throttle steady. The loss of RPM/power would build and prevent the motor from turning. I am not exactly sure why the symptoms never presented when I first turned the vehicle on. Perhaps whatever chunk was lodging itself in to the exhaust pipe was falling out, or perhaps I am just to gentle on a cold motor to throttle it. Anyway, thats the scoop.

Thanks for your input everyone. Now to take care of those motor mounts.....

2ToyGuy

Thanks for letting us know!
That might save another guy a lot of frustration, and chasing their tail.

I was told by several professional mechanics I used to work with, that it's a good idea to beat the catalytic converter with a ball-peen hammer every year or so. Not enough to damage it, but give it a few good whacks all over it. It loosens up the bedding materiel, so it functions correctly. I do it to mine about once a year, and it does seem to make a noticable difference in how the engine runs, as well as the smell of the exhaust. Whatever that's worth. We don't have to smog the vehicles where I live (south central Oregon, formerly the farthest SW AZ there is), so I don't have any actual, measured, data to support all this, just my personal experience.
Obviously not applicable in your case, but I just thought I'd throw it out there.

Good luck!
Pat☺