Yotaguy0001

92 4runner 3vze 183,000 miles. Just replaced the head gaskets 2000miles ago. Replaced: Plugs/Wires/Cap/Rotor, TPS, Coolant Temp Sensor, Distributor (used), ECM (used), Coil (but not igniter), Fuel Filter, O2 sensor. Removed all the egr system. The truck will run great until driving for about 30min, then will surge/hesitate. When I push the pedal, you can hear the engine taking in more air, but it's like I'm up against a brick wall. It will not gain rpms, and sometimes backfire. It will usually go away if I pull over and turn off the truck and restart it. SOMETIMES, it will all of a sudden return to normal and gain rpms while the problem is occurring. It's like I'm up against a brick wall, and then a "switch" is flipped the engine gains rpms like it's supposed to. Like the title says, it's completely random. It will go for weeks without an occurrence, then I'll go through periods where it does it all the time. VERY FRUSTRATING! Could a bad igniter do this? Fuel pressure regulator? Fuel Pump? VAFM? It's the worst up hills of course I already have the link to the FSM.

wii_tarded

Bad gas? Clogged injectors? Replace the EGR system and see if the problem persists.

93toyrunner2

Have you checked for codes? I am betting you will have a 52

Yotaguy0001

no codes, egr is completely removed. Could be bad gas.

Yotaguy0001

I forgot to mention when the problems occurs, the engine idles at about 500rpm, and is very rough. Could the temp sensor in the VAFM be sending the incorrect information? This only happens when hot. The engine runs great when cold/recently warmed.

wii_tarded

Have you checked all your vacuum hoses?

Yotaguy0001

I've checked most of them, still kinda going though them. I was thinking vacuum leak too. But I just don't even know anymore. I have this ticking I can hear in the cab when I let off the gas, and it goes away when I press the brakes. Could that indicate a leak in the brake booster? The 3vze is a PITA to diagnose.

Yotaguy0001

I believe the problem may be the VAFM. I turned the spring tensioner inside the VAFM to the left (reducing the resistance on the plate?) and it seems the hesitation may have been solved. To early to tell.

Anyone have a VAFM for a decent price? I'll list the part number later.

wii_tarded

I may have one, will have to check this weekend.

Yotaguy0001

Tested the AFM as per FSM, everything is with in spec, except E1-FC. It's supposed to be zero ohms in any position but closed; I have 1 ohm. I'm not sure what to think of it. What do you think? I'm starting to think it's the knock sensor retarding the timing. I have been running 87 octane. Maybe I'll try 89 and see what happens. I may just end up doing the knock sensor relocation mod, seeing how I don't want to tear the top of the engine apart again; as I just did it. It's probably the wire. I didn't know to ALWAYS replace it when you have the top of the engine apart. This is my first 3vze; I have to claim ignorance here.

93toyrunner2

This is why I wrote earlier that you would have a code 52. I had a wiring problem with my knock sensor, and when I would push over 2000 rpms for more than 6-7 seconds, the knock sensor would throw a code, and retard the timing. It would run rough for about 3 minutes, then all problems would just go away, and run normally. However, the CEL would remain on until I restarted the engine. I relocated the knock sensor and rewired it with coax, and no more problems.

Yotaguy0001

93toyrunner2 - your mention of code 52 got me thinking before. Thank you. But I don't have any codes. So I think maybe the wire is good, and the sensor is faulty.

Yotaguy0001

My problem occurs when I'm at around 1500rpm for a long period (cruising down the road) and then I need to accelerate; and there just isn't anything there. Sometimes it goes away in a second or two, and then power is restored. Then other times there is nothing I can do, but pull of the road, shut off the engine, and restart.

abecedarian

E1 is a voltage source. FC terminal is the fuel pump (Circuit Opening Relay) contact.
The difference between 0 ohm and 1 ohm is insignificant. All that FC does is take the voltage from E1 and send that back to the Circuit Opening Relay so the COR stays energized so the fuel pump keeps pumping.

There's no particular reason that the engine shouldn't rev over 2000, even with a knock sensor issue, unless the igniter module isn't functioning properly.

Yotaguy0001

The fsm doesn't have a procedure for testing it. At least - http://www.ncttora.com/fsm/ - doesn't seem to. How do I test it? I can get one for $50 locally. I just need to know how to test it, if possible. There was some corrosion on one of the terminals of the igniter btw.

abecedarian

I don't know of any particular means to test the igniter.

It takes the signals from the distributor, sends signals to the ECU, and controls the ignition coil and timing. If it's failing, it should throw some sort of code (no NE, no IGF, or similar) but may not.

Sorry I can't help more than that.

Perhaps you can get the local one to "test" the theory, and either pay for it if the problem disappears or return it.

93toyrunner2

follow diagnostic on page 13 of this pdf:
http://www.ncttora.com/fsm/1990-1995...e/troubles.pdf
And, clean the contact surface under the ignighter and the bottom of the ignighter with a wire brush.

Yotaguy0001

Do you mean under the frame that the igniter is bolted to? By that I mean the two bolts that bolt it down to the fender. Or do you mean the 4 philips head screws that actually hold the igniter to that frame. Does the igniter ground through it's case?

93toyrunner2

Yes, and Yes.
Remove the 2 12mm bolts that hold it in position, and use a wire brush (wire wheel on a drill) to remove any corrosion from where it mounts and on the bottom of the mount itself.

Yotaguy0001

The problem is still there after cleaning the grounds. 1 of 3 things happens; 1. The engine bogs when the accelerator is depressed, no matter how far. You could floor it and nothing will happen. It bogs for about 5-10sec, and then power is restored. 2. It will bog, then backfire. 3. It will buck like a bucking bronco. It all 3 situations, letting off the accelerator fully, and then keep trying to depress the pedal, will eventually result in normal operation. Like I said before, sometimes is wont go away without pulling over and restarting the truck. Whatdo you think? Fuel pressure regulator? Or malfunctioning fuel pump? Is there a way to test is the fuel pressure regulator is working correctly? I don't have a fuel pressure tester. Thanks for the help.