4.0 spark on 1,2,3 No spark on 4,5,6 I am losing my mind.

I got toyota with a blown 4.0v6. Number 4 rod had come apart. I put in another 4.0. It has good compression. It has spark on 1,2,3, but not 4,5,6. I can get spark from the all coils on 1,2,3. I have power and ground at all coils. on the coils, I checked for continuity and the other 2 wire's that are not power and ground make there way to the ecm plug. I even got a second ecm with the same problem. I am frustrated. Any help

 

Here's a link to the wiring diagrams. https://www.customtacos.com/tech.old/files/05FSM/wiring.html

 

I read that the STA fuse will have power when the engine is cranking. It does not. I checked the STA relay and it had burn marks on it. I tried the relay in my DD and it worked.

 

First thing to do - swap your 1 2 3 coil packs to 4 5 6 (and 456 to 123). See if 456 fire or fail to fire.

 

Are there spark plugs installed in those cylinders?

 

All the coils work. It seems the STA fuse does not get power when cranking. My dd does.

 

I put a second set of plug's in it today thinking the other set were fouled.

 

Cool. Sometimes the easiest things can be missed. Is it working now?

 

I ended up switching out a vvt-i Cam Camshaft Timing Oil Control Valve to match the the truck. It probably had nothing to do with it. So I had spark at all 6. I put in new plugs, but it only begins to start. The STA 7.5 fuse that should have power during engine cranking does not have power. Immobilizer???, or ignition, I am going into the dash today. I do want to burn this thing to the ground, LOL? I have a second steering column. I guess the idea is now is find out why STA 7.5 has no power.

 

I think I have to walk away for a while. I have to start over. Engine cranks and seems like it is about to run, then don't. I tried a second ecu, I tested the wires to the coils, checked spark, it has fuel as the spark plugs are wet when pulled, tried a second set of plugs, and I do not know were to begin. Who would have thought an engine swap would have been the easy part.

 

Does your truck have an immobilizer on it?

 

Yes, I didn't change the immobilizer or the key. I tried the paper clip at the obd11 port for 30 min, With no change. IDK would the dealership be my only option?

 

A couple of points to make. You replaced the engine and the ECU. The VIN and the ECU must match. Your issue may be as simple as resetting the ECU registered VIN.

 

The ecu is the original now. The engine is the only part that is not original. Does the ecu need resetting when swapping out an engine? Or did the ecu get cleared when taken out.

 

Maybe if I lift it and put tires on it, it will run then, LOL!!! The days when I do not like working on stuff my self are now here.

 

The VIN in the ECU, Immobilizer and engine should all match. It wouldn't hurt to get it checked to make sure...

 

Im running an ECU in my truck with a UCON that doesnt have a matching VIN. I just had to reset the immobilizer for 30 minutes and then it cranked right up. Did you follow this procedure?

1. Disconnect battery
2. Swap new ECU into truck
3. Paperclip across pins 4 & 13 of 16-pin DLC3 (AKA: OBD2) connector
4. Reconnect battery
5. Hook up battery charger
6. Turn on ignition
7. Wait 30 minutes (use a timer, has to be at least 30 minutes)
8. Turn off ignition
9. Remove jumper from DLC3 connector
10. Try to start the truck

 

It won't heart to try one more time!

 

Nope did not work. Sounds like it fire's then not, fire's then not.