Just a little background, 90 4runner 3.0 v6 automatic newly rebuilt motor, new tps new fuel pump, fuel filter, and timing belt. Heres the problem Its been running irratic since I've reinstalled the motor. At first I got the timing set, or so I thought I did, ran it and found that it had a hard time cranking over so I rechecked the timing and it was advanced to the 12 o'clock position so I had to move the distributor back a notch to get in to 10 deg again. Now it would idle but couldn't rev up past the point when the tps is at .35 and the ohm meter goes to infinity, but if you go past that it would run crappy. So I put in a new tps and got it running like it supposed to. A day later it starts to die out when I let off the throttle in town so I gotta put it in neutral while rolling and restart. So it progressively runs worse until I can no longer start it. It would also run differently every few times I would start it, sometimes it would start right up other times it would run like it was missing. I just changed the fuel pump and that didn't help. I noticed that if I put my forearm on the top of the air filter housing I would get shocked like when you grab a spark plug wire but not as strong so I know something is not right there. I also tried swapping out distributors but it still runs the same. Any help would be greatly appreciated.

 

Sounds like a plug/coil wire or dist cap arching somewhere to the air filter box. Check where they come in close proximity to the air filter apparatus. You might also take a misting bottle and mist the area with water and see if it causes any arching. If it arcs anywhere then you found a problem.

 

I have never been shocked by an air filter assembly. That is a new one for me. Start looking for a bare wire somewhere and I think you will solve your problem when you find that. Pop the hood in a dark shop or dark night and you should be able to find it quick that way. Also while doing that check your plug wires.

 

Thanks for the responses. Another thing I found is that when I tested the distributor wires for continuity to the ecu all wires tested out fine but when I cross tested them to each other two wires had continuity? I looked up the wiring diagram and it shows a direct link from the distrubutor to the ecu and at no point do the wires intersect. I cut the wires and ran wires directly to the ecu but that helped nothing. I'll do the night test on the wires tonight. Thanks!

 

Check your ground wires. Especially the ones from engine to frame and engine to battery negative. Do a voltage drop test from battery negative to engine block. Should be close to 0v.

 

Alright I checked my wires in the dark last night and the only thing I found is that my coil wire going to the distributor glows and if I touched it it looks like the matrix but I didn't get shocked. Ground connections to the motor are good but I'm not sure of how to do a voltage drop test.

 

Attach one voltmeter lead to the negative battery terminal and the other to the engine block. Anything above 0.20V means there's a bad connection. A good connection will be <0.10V. You probably need plug wires too.
http://www.fluke.com/fluke/uses/comu...seVoltDrop.htm

 

What would make your timing change without changing or adjusting anything? I would start it and timing would be right on, I shut it off start it again and the timing would be super advanced. So I would retard it to 10 deg run it for a while shut it off start it and it would be off again so I would have to advance it. Any ideas?

 

Are you connecting terminals TE1 and E1 when checking the timing?

 

Yes I have it jumped

 

At normal operating temp each time? I'd say recheck all your grounds.

 

I checked out my grounds today and they were good. So I get it started and it idles fine, when I throttle up it sputters and stalls just as the throttle starts to open and the timing is super advanced. So I put the throttle right as it starts to die out and after a few pops (misfiring) the idle comes down and timing is magically in place and the throttle is operating fine. So this goes on, sometimes it will start fine others ˟˟˟˟ty and every time when the idle is high (1500 RPM) it will run ˟˟˟˟ty and when the idle is at 900 RPM it will run fine. The only thing that is changing is starting it different times. So what would cause this, what controls timing, ECU? Distributor? Would a bad distributor cause this?

 

Is your TPS adjusted properly? It's important that the idle switch on the TPS is closed when you make the timing adjustment - otherwise the ECU doesn't know you're at idle and will muck around with the timing while you're trying to adjust it. It sounds like maybe sometimes the switch is closed, and at other times it's open, giving you inconsistent results. Put a meter on the TPS IDL terminal (pin 2, yellow-white wire) when the engine is at idle and make sure it's reading 0V.

 

RJR I checked the idl pin at idle at it had 0v. Now with the engine running and the Tps disconnected it ran smoother than with it connected? Now this is just running the engine in my shop not on the road. I thought the Tps controlled the engine? so how would it be able to throttle up with it disconnected?

 

The ecu is calculating the throttle opening based on rpm and airflow. Check the signal from the tps through the throttle sweep, voltage should change smoothly. If it's spikey and jumps around, replace it.