I'm voting for a bad ECU even though you had it checked. I went through this with a V6 Camry, I also forgot to disconnect the battery and to make it worse my buddy left the ignition on while I was working on it, until I heard something clicking. Got another igniter and it ran for a few weeks and then died, another one lasted a couple months. After testing and double checking everything I got another ECU from Ebay...runs like a charm and I have no idea why that ECU kept taking out the igniters...

D

 

Make sure the diagnostics plug is bolted firmly to the intake with a clean surface (grounded).

 

My ebay igniter arrived today, put it on the truck and checked for fire at the plugs. Still the same problem, no fire from coil pack 1. Ebay ECU next I guess?

 

Have you swapped the #1 and the #2 to see if the issue moves with the pack?

 

Yeah, i tried that. Not the coil

 

The coils share a power supply with the igniter. Should be black wire with red tracer. Should all have 12v in the run position. I believe the igniter provides the ground. And the igniter is grounded on the intake manifold above the oil cap. No spark from only one coil and its not the coil sounds like maybe a wiring issue. Computers and igniters very rarely fail. Have you re-checked for trouble codes?

 

I am flat out of ideas here. I'll look at the hard circuit diagram in my hard copy FSM later for the #1 coil.

 

Double checked the above today. 12v present at each coil and the igniter with key in run position. Ohm tested the other wire (ground) from each coil clip back to the igniter. Then I unplugged the igniter and tested the coil side of the harness again, this time for continuity with ground (short). Tested the igniter ground (solid brown, slightly thicker than the rest). Also scanned for codes again. No problems found.

 

Looks like I may have found a compatible used ECU. There is a slight difference on the numbers on mine vs the one for sale. Mine is pictured. The one I am considering buying has the last digit of this line different:
175000-90020 mine
175000-90010 seller's
Everything else matches. The part number on both is 89661-3D310. I am hoping that I can use this computer plug and play. Anybody know for certain?

 

That may be an older version or different lot # than your computer. The part number that differs is the manufacturer part #. Your Toyota part # is the same so it should work. I think

 

I ordered it, fingers crossed while I wait on shipping again

 

I thought the igniter grounded by bolting to the sheetmetal

 

Maybe it does as well, don't know. But it definitely has an external ground wire that bolts to the intake and they wont run without it. I've had trucks towed in after someone did spark plugs and forgot to tighten the ground

 

I don't have the motor you have, but it just seems weird that an ECU would fail after a timing belt replacement. I 'am aware you left battery connected during repair, but did you check any and all fuses, links or possibly something not plugged in. Just wondering as I'd hate to see you put in an ECU for nothing. Man, I hope you find what it is.

 

I've done that one and it is super easy to overlook. Mine was just loose.

I'm thinking it would also be possible to hook the hoses up wrong to the IAC. I've never seen anyone admit to that though.

 

replacement ecu is in. problem remains the same...no spark from coil pack 1.
arghhh!

 

after a few attempts to crank, she started and idled very roughly for about 10 seconds or so at ~1300 rmp. Threw a code, p0340 camshaft position sensor. I removed and meticulously cleaned the camshaft sensor, the code quit showing up.

Now back to starting for a second or so, then dieing immediately. No error codes presenting.

 

Time to go basic. Check the trigger wire for the coil, make sure it is properly connected on both ends and is not broken.

 

Still stuck here. She starts for a second, then dies. I have ruled out the following:
ECU
Igniter
Cam sensor
crank sensor
coil packs
wiring shorts between all the above
timing belt/pulleys are all installed appropriately.

I am not getting a check engine light.

Any thoughts, suggestions? I terribly frustrated and out of ideas. Nearly a month now without my 4runner, I miss her.

 

Vacuum leak like was suggested above? I would run a boost leak test and see if you can spot any leaks. If you have a big enough leak it will act like the MAF sensor is disconnected and do what you are seeing.