Alright guys, I need some help. I have 2 4runners (1991 and 1993) and the 1993 is haunted. I just had the heads redone on the 3.0 and it runs perfect and idles great. That is until I go 25 miles. Then it surges bad and loses power. It won't go above 2500 rpms when it surges. I can put it in neutral and coast and turn the key switch off and restart it then it runs perfect for 2 to 8 miles. When it surges the idle is good but it wont take gas. Again restart and the problem is fixed for a short time. I've changed the fuel pump and filter, 02 sensor, knock sensor, TPS, MAF, distributor, ignitor, and coil. The computer and coolant sensors are next but I'm tired of changing parts. Has anyone heard of this before? Thanks Also no check engine light

 

Instead of just changing parts, get yourself an FSM and start testing parts.

Check the Idle air control valve, and the coolant sensors. The ECU is not likely the problem.

 

Thanks, I will try to get one. The Haynes manual I have doesn't have the electrical spec. ranges in it. The reason for the parts change was because of the other 4runner that runs great. I have all the parts I can try for free. I was thinking something electrical is breaking down and the restart resets the computer until it checks the system again.

 

Haynes and Chiltons are $19.99 worth of tobacco rolling paper lol

 

I'm finding that out.

 

I have 4 or 5 different DIY books on my 4Runner including the FSM, Haynes and Chiltons, the FSM blows them all out of the water!

 

Thanks, I will invest in one.

 

my truck had almost the same problem. idle perfect. run great after a short period it would boog down. turn off the key for about 10sec restart problem gone for another short intervol. swaped air meters. unpluged o2s, check fuel presure while driveing. adjust tps. finalty had to back prob ecm while driveing. and when this condition would happen the o2s would go super rich. problem was in the ecm. i found a used computor for $50. you try back probing at the ecm and see what the signals look like at the ecm. this way you check the wires also. good luck. maybe check your back pressure in the exhaust. or just disconnect the cat and leave the o2 unplugged. is if you get a change.

 

Finally I'm not alone. I don't know how to back probe the ecm. I'm good with a multimeter, but I will take the other computer out tomorrow and install. Thank you!!!!!!!!!

 

Have you checked the ignition timing?

 

Guts in the coverter broken into chunks?Builds up pressue blocking the down flow side, cut it off all the chunks settle down.Hit the cat with a rubber mallet. See if it sounds like it came apart.

 

The timing was set and tried every position possible. We tried a different ecm today and that wasn't it. We will try the converter.

 

Removed the converter today. Does the same thing. Its driving me nuts. Drive it until its good and hot (25 miles) then it surges. Kill the ignition and restart and it runs perfect. runs perfect 2-8 miles then the same thing. The fuse box gets fairly warm where the 80amp and the EFI relay is. I've changed the relays. Maybe a voltage drop????????????

 

FYI!!!!!!!!!!!!!!! The vehicle set for a while due to the blown head gaskets. I guess something got into the tank and gummed up the fuel tank. The original fuel filter stopped up immediatly and the second one was 3/4 stopped up. Installed a 3rd filter and it is good. Lesson learned. If it sets awhile and runs weird, clean the tank!!!!!!!!!!

 

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A rust hole was on top of my tank and a bunch of sand got in the tank. So much silt got through the fuel filter it plugged the screens on the injectors. Fuel tank removed cleaned and patched. new fuel pump/prefilter 2 new fuel filters which i relocated to the inside rt wheel well for easy replacement. Removed and cleaned injectors. she runs with more power than ever. My guess it was like this for a while and slowly clogging the fuel filter..