Hey everyone, new here and hoping to get some guidance from the experts.

Truck: 1996 F350 7.5L (460) with E4OD. 2wd Centurion

Background: Ran great all summer long put around 15,000 miles and it was great. parked it this winter ran it for a quick second with the postive and negative wires loose and the truck went nuts shut it off and tightened the connections and now i have this issue.
Issue:
Truck runs and drives great when cold. Once it reaches operating temp, it starts misfiring and the tachometer goes crazy. no power under load. If I give it more throttle, it holds around 1800 RPM and smooths out somewhat, but the tach still jumps around. When I unplug the 2-wire ECT sensor, it runs great even when warm (check engine light comes on, obviously).

Here’s what I’ve replaced so far:

• Distributor
  
• TFI module
  
• Ignition coil
  
• Spark plugs (look recently replaced and in good shape)
  
• Plug wires
  
• Engine Coolant Temp (ECT) sensor
  
• O2 sensors
  
• Battery and alternator are new
  
• Verified coil positive voltage ~11.7V key on engine off
  

Additional info:

• Sharp random pops when warm
  
• Tach becomes erratic only once hot
  
• Transmission codes present:
  
  • 626 Coast Clutch Solenoid circuit fault
    
  • 624 EPC solenoid circuit fault (KOEO and continuous)
    
  • 637 Transmission oil temp circuit above max voltage
    

It runs perfect cold every time. Problem only starts once fully warm. Unplugging ECT makes it run great.

At this point I’m leaning toward a wiring / ground / voltage issue rather than fuel or ignition components since so much has already been replaced.

Any insight on shared grounds, PCM power feeds, or common 460/E4OD harness issues would be appreciated. Trying not to throw more parts at it.

Thanks in advance.

 

That is a lot of new parts, there's a chance they aren't all good.

To me, it sounds like its running lean, since it seems to run better in open loop.

Look for vacuum leaks/exhaust leaks, and check the plugs again after driving for a while, that should give a good indication.

How old is the fuel filter?

 

Thank you for the reply!
I forgot to add that i changed the fuel filter this summer just out of maintenance.
Thank you.

 

Check your fuel pressure. https://www.ford-trucks.com/forums/1...rd-trucks.html
I agreed with above. Once it goes into closed-loop, it starts metering back fuel. If your fuel pressure is low, it'll screw the ratio up.
Those codes may be caused by a damaged transmission wiring harness on the passenger side of the transmission.

Nice truck, btw.

 

After checking the fuel pressure
Check the codes, check the ignition module, check the capacitors in the processor
I would have a spark tester on there and a fuel pressure gauge taped to the windshield and go for a few test drives

 

I’m going to check the items you mentioned and review the thread you shared. I’ll also measure the fuel pressure (PSI) and report back with what I find.

I really appreciate all the help! I got the truck on a smoking deal and definitely don’t want to get rid of it.

 

Make sure to do what manicmechanic007 says and watch the gauge while driving to see what it does under load.

 

Today I went out to the truck to run the fuel pressure test that was recommended. When I went to start it, the tachometer immediately started going crazy, jumping all over the place. While I was watching under the hood, I noticed the distributor rotor was spinning extremely fast, much faster than what I would normally expect.

The truck ran briefly and then died shortly after.

This happened before I could even get a fuel pressure reading. The behavior seemed pretty abnormal, especially the tach bouncing around and how fast the rotor appeared to be spinning.

I took a couple videos of what it’s doing and attached them below.

Has anyone seen this happen before or have any ideas what could cause this?

Maybe a shorted out ground possibly thanks

Here are the links to the videos of whats going on

 

Your distributor is not spinning, it is driven by the camshaft.

If that is the coil activating, I would assume something is shorted, possibly the PIP sensor, but it could be something else.

 

That is a brand new distributor so maybe a bad ground going to the PIP? What is odd is if I turn it off let it sit for 20-30 second it runs and does not do that until it goes up in temperature and it starts acting up again

 

New does not mean good, do you still have the old distributor? Put it back in and see if the problem persists.

 

the old one was doing the same thing that is why i replaced it in the first place but i will do that and get back to you