1994 V6 performance question

[oneowner1994]

Have a 1994 4runner with automatic V6 and 306K miles. One owner, drove it off the lot brand new 24 years ago next month. Since last summer, I've experienced an intermittent misfire and surging on acceleration. The check engine light is on constantly, however I cannot get codes to display. I've asked about that here before and got no answers. Thus, I'll be "throwing some money" at it and hope some others' experience can help me throw it in the right direction. The plugs have been changed, plug wires test good. Checked as many vacuum hoses as I can find and replaced a couple. Changed the fuel filter recently and O2 sensor. The symptoms are: (1) engine starts quickly and runs smoothly at startup (2) accelerates smoothly until normal temp is reached after which it surges when accelerated (3) also sensitive to ambient temperature, now that's it winter, it occurs less frequently than last summer and fall.

The first thought is the fuel injectors, but doesn't respond to cleaners and so I'm reluctant to begin that task until I've checked other possible causes. Any suggestions will be appreciated. As noted above, no codes are available, so I'll be using performance symptoms and physical inspection only.

 

[Dropzone]

when you say you can't get codes to display did you jumper the terminals to on the diagnostic port on the passenger side wheel well?
https://youtu.be/do7ulTOvQPc

 

[oneowner1994]

Absolutely. Did it many times and the check engine light is on constantly at ignition on with no flashes. Read every article I could find to see if best to install jumper first before ignition on or after. Used paper clips, copper wire for better conductivity, but to no avail. Pulled EFI fuse and tried after that, still no codes and check engine lot on while running. I had never seen the check engine light on after startup until 270k when the fuel dampener had to be replaced and the shop left the EGR valve connector off and only partly bolted back on. Thus, I know it functioned once and was able to get codes. Considering installing the jumper and testing for current across the test connectors.

 

[oneowner1994]

Let me add another thought. Most parts have a "mean time of failure" that often isn't included in regular maintenance schedules. From my shade tree mechanic days when most of us tinkered with flathead V8s, rough running after warmup was often caused by a bad distributor cap. It expanded with heat and increased the spark gap. The rotor was changed once on this car and cap is the original. Thus is 24 years old and 306K on it. Looks clean, no visible cracks and uncorroded. On some thread that I read somewhere or another, someone mentioned that the distributor caps should be changed every 60K. Simple enough to do. Anyone heard of that?

 

[Ahlem]

How old are your spark plug wires?
What do the contacts under the distributor cap look like where the rotor spins past?
What do your spark plugs look like?
I'd suggest getting some contact cleaner and clean the connectors at the TPS and the AFM and at the fuel injectors you can get at without removing the intake manifold.
This is all fairly low cost stuff.

 

[superex87]

The electronics on these trucks are aging. If it won’t display any codes it could be an issue with the computer. It’s not too hard to remove the computer and pull it open to inspect the capacitors. There’s a good chance they are could be leaking. An easy test would be fine another computer and swap them then try to pull codes.


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[oneowner1994]

Spark plug wires get changed every 100K or so. Mine are about due, but tested good with an ohmmeter. Spark plugs less than 6 months old. Last ones were all gray and no abnormal wear after 70K. New plugs seemed to reduce the misfire a little bit, but not much. Grabbed some articles about testing the TPS and the VAFM and will do so. Not much written about the VAFM, but interesting thought. Traced a sound like a noisy bearing to the VAFM.

 

[RonJR]

First, since it doesn't have a crank position sensor, the 3vze engine does not have misfire detection per se - the only CEL code you would get due to a misfire would be some kind of emissions detection (too rich, most likely).

Second, since there are no codes, you might check the CEL wiring between the light itself and the ECU. There is a blue wire between the CEL and pin 5 of the ECU. The ECU lights the CEL by pulling that wire to ground. If that wire is shorted to ground externally, the CEL will light even if the ECU knows nothing about it. You could pull off the ECU connector and then test for continuity of that wire to ground. It should be open, or at least a reasonably high resistance.

 

[oneowner1994]

Thanks for your comments. Have to put this project on hold for a couple of weeks. Sitting at a stop sign waiting for traffic to clear and got rear ended by a pickup truck with a grill guard. Almost no damage to bumper, lots of damage to tail gate, but glass OK. They totaled the vehicle, but I'll keep it. 24 years on the road and first accident. Got to work on finding a tail gate replacement now.

 

[Dropzone]

Thanks for your comments. Have to put this project on hold for a couple of weeks. Sitting at a stop sign waiting for traffic to clear and got rear ended by a pickup truck with a grill guard. Almost no damage to bumper, lots of damage to tail gate, but glass OK. They totaled the vehicle, but I'll keep it. 24 years on the road and first accident. Got to work on finding a tail gate replacement now.

Well that sucks. Glad you are OK. Surprised they totaled it over the tailgate. Glad you are gonna fix it.
Can I ask how much you bought the 4runner back from the insurance company for and how much they gave you?
My insurance company asked me to remove the full coverage every now and than.. I say nope

Good muck in your search for a tailgate I have one stashed just in case.

 

[oneowner1994]

Picking it up at the body shop tomorrow. They said they will pay me $2360 and I keep it. Quite generous. It's not my insurance paying, it's the other driver's insurance. As best I can tell there is no damage anywhere except the tailgate. No impact to the corners, tail lights and nothing to the floor of the rear deck. The plastic on top of the rear bumper is damaged, but no noticeable damage to the chrome bumper itself. The plastic bumper piece is about $125 plus shipping and found a 94 tailgate the same green color as mine in Iowa for $218. I'm in Missouri so should be reasonable freight. If I'm lucky, will need no touch up painting and look just like it did before. I was surprised that they totaled it also since I had already researched the parts. My wife dropped it off, picked up the rental car and didn't get home before they called about totaling it.

 

[kc15842]

I have a red tail gate its yours just pay freight.

 

[Dropzone]

That's not too bad. If you have a couple of extra hands swapping the tailgate isn't too bad. It is awkward with the glass in there.

 

[oneowner1994]

Just finished doing some temporary repair to the tailgate. As noted, the glass is OK so there are no leaks in this cold, wet weather. The center of the door was significantly pushed in. However, with a block of wood and a screw jack placed properly, the whole center part popped out like the lid on a pickle jar and went back in place with only minor dents remaining. I was amazed how little pressure it took to pop it back. There is a significant crease about 6 inches from the driver's edge of the tailgate that allows the window to travel all but one inch of the way. Good enough for now until I find a tailgate. I rarely require access to the back area.

Online salvage parts search shows several places with green tailgates (Evergreen Pearl) in excellent shape. Some aren't that far away. Indeed, I expect the weight would require some help.

 

[SaulG]

1) "It's not my insurance paying, it's the other driver's insurance."
2) "surprised that they totaled it"

How can some one else total your vehicle ???!! Do you have full coverage?
May do some "comparables" shopping no way a tailgate totals a vehicle.

 

[oneowner1994]

Yes, I have full coverage. The insurance adjuster sent me the estimate. Apparently they proposed brand new Toyota parts that added up to $2400 and with paint and labor, the estimate was over $3200. Thus they sent me a check for the value of the vehicle and I kept the vehicle. That's what they offered and I accepted it. I might have argued and insisted on fixing it with used parts. I had already checked it out closely and there was no damage to the body below the tailgate or to the sides and their estimate only included tail gate parts and the rubber top of the bumper. I was never asked if I would accept used parts or not.