Ive rebuilt the motor and only has about 100 miles on it. The motor is running rough so I started to pull the spark plug wires one at a time to see what would happen. When I remove the plug wires on each cylinder the motor runs rougher except for the #1 plug:

I have not pulled the spark plug yet but the are practically new and when I put the wire near a metal part I do see spark.

Except for a bad plug, is there anything else that could be causing this?

 

Seems simple, but maybe it's a damaged distributor cap? Or just a plug wire that's not quite hooked up? faulty ignitor?

 

Putting it near metal would indicate spark is getting to the plug.

First, do a compression test. I know you just built the motor, but start with the simple stuff. Test the OHM's resistance on the injector, see if it is able to fire, then test the harness for injector pulse. Try swapping plugs. Do a leakdown test.

 

try checking to see if the injector is firing...

 

Is there anyways to actually fire the injector once it is out of the truck? I wouldnt mind testing all of them and cleaning them if it is possible.

 

take them out and send them out to an injector shop for a bench flow test and cleaning. its way worth knowing your injectors are flowing well and are giving you a good spray pattern.

 

x2 on the injector cleaning. It's either the injector or the injector wiring harness. There is a method in the FSM for testing the injector harness wiring all the way up to the injector. Those injector harnesses are a bit fragile and I have read of many instances (particularly after major engine work) where a wire broke inside the harness. I would put my money on the harness but you should still have the injectors cleaned and balanced since you just rebuilt the engine. You can test the injector wiring while the injectors are off being cleaned.

 

OK... I pulled the plugs and the #1 plug was fouled. I replaced it but now I wonder why it would foul since it is a newly rebuilt engine.

I just check the compression and my compression is 170-175 .

I suspect wince it takes so long for the engine to build oil pressure (20-30 seconds) that the valve seals may be wearing out prematurely.

 

the plug was fouled with what? oil? fuel? coolant?

 

I feel real dumb right now..hehehehe...I never checked to closely..I just replace the plug and threw the old one away.