Scott Thomson

Not sure if this is the correct subforum to post this

I just finished a 3.4 swap into a 94 pickup,
Motor is a 96 Tacoma 5vzfe m/t into a 94 pickup, 3.0 m/t

Swap went fairly well, pretty straight forward compared to my last swap, followed the diagrams and got the wiring all hooked up to what I believe is correct, it fires up right away and idles great, but if it's cold and you try to rev it even in nuetral, it will just backfire out the intake and die, but if you wait till it warms up, it will rev fine but lacks any power at anything other that idle, and if you rev it in neutral it spits out tons of black soot. I've cleaned the maf, made sure the ignitor is grounded well, o2 sensor is good, I should also mention, I dont have a cat yet so I haven't hooked up the secondary o2 sensor, I've also deleted all the emissions stuff simply because it didn't come with the motor (junkyard motor, no access to donor truck and the 3.0 stuff was junk/missing)

I've double checked my wiring, pretty sure it's all good, I'd pull codes but I don't have an obd2 port wired in yet, I'll probably do that in the next few days, but the issue seems to be ignition timing related to me, but I'm not sure why the ecu wouldnt be advancing the timing, I did replace the timing belt before I did the swap but I made sure it was all lined up right, so I'm not sure what could cause it, I'm not that familiar with these motors, maybe someone else might be able to tell what I missed?

-burzum-

have you checked the o2 sensor with a meter? If not do so, and do it at the ecu by backprobing with safety pins or using a obd2 tester with live data capabilities which would also let you check your fuel trim levels etc. Double check your timing belt belt is in position, i tis VERY easy to be off by a tooth even if you had it lined up right. The trick here is to line everything up tight with all the slack in the belt on the tensioner side when you are lining things up. also try to shake the harness around and see if it changes the idle, might be a loose pin or broken wire somewhere. Also a possability would be a coil pack or igniter. go through the flow charts in the fsm.

Scott Thomson

I did a little digging last night, got an obd2 port hooked up, was only getting one code, p0100, so I followed a test I found for the maf and was getting no resistance, and the voltage wouldn't change with airflow, sounds like the maf is cooked, but before I replace it, is there any wires going to it that I would have had to splice in? Maybe I missed something?

-burzum-

You have to hook up the white/blue wire ( B+). this also powers the O2 sensor heaters, evap vsv, and idle air control valve.

-burzum-

check for power at this wire while engine is runnning

Scott Thomson

Cant find any white/blue wires like that on mine. based on the diagrams it's a white/red and ya, it's hooked to a switched 12v source, doesn't start without it

-burzum-

I am looking at a 1996 3.4 wiring diagram right now and at II3 - 16 is a white/blue wire that does as stated. This needs to be hooked up to the White/red wire on the 3.0 side at IH1 - 16

you should be able to see this white blue wire on the MAF as the B+. It should have 12V while running or the MAF will not put out a voltage signal.

Scott Thomson

Ok, I'll dig into again, I'll connect it and post the results

Scott Thomson

Ok, I got it running perfect now, no check engine light even, which is nice. That white/ blue wire is actually a white/ red, now the confusion comes from the face that I did have it hooked up, but it had broken off at some point (must have accidentally yanked it off when I pulled the ecu back out) Hooked it back up and it runs perfect now, except for a slight misfire, so problem solved! Thanks for the help

-burzum-

Right on, im glad you got it running. I realized you have a tacoma motor, i was looking at a 4runner diagram! must be a few differences. At least you got it fixed.