I've been helping a co-worker fix his F150 that spun a couple bearings, broke a rod and seized up. Truck is a 4x4 with 4.6L V8 SOHC. Truck was running well prior to bearing failure. We pulled the engine out of the truck and sent it to one of the local rebuild shops (reputable shop that does a ton of engines).
We got the engine back with the timing cover on. We did not check the timing (in hindsight I really wish we had just to rule it out). Reinstalled the engine and tried to fire it up. Truck had no fuel pressure which we traced back to a locked up fuel pump (truck had been sitting ~4 months).
We replaced the fuel pump and it fired up. But it idles with a heavy surging and misses / backfires. After only about 60 seconds of idling all 8 plugs were fouled. We cleaned the plugs and started looking for vacuum leaks / unplugged sensors. I've been over it 4-5 times and cannot find anything out of the ordinary. Truck is running like it's way out of time or the fuel mixture is massively off (it sounds like we have the spark plug wires all crossed, but it's coil on plug). I chased sensors for a bit with my multimeter but ended up frustrated and did not finish checking all of them (IAC measured good, as did input into TPS, did not have a piecing probe to measure output).
I bought an OBD2 code reader which will be here Wednesday. I will pull the codes and report back. In the meantime can anyone offer any suggestions on what to focus on? Or some general troubleshooting advice? Thanks in advance for the help.
