Aright boys, I'm stuck


I apologize for the length, just wanna give as much info from jump. I'm also posting this in other areas to try and get this diagnosed.


Truck background: '93 F250 XLT, 4x4, 7.5L gas, E4OD, 186,000 miles


A few months back, I did the 3G alternator conversion, used a new alternator intended for a '93 Taurus, and wired it up using the kit from Painless. Everything went in seamlessly and ran fantastic without issue.


I recently sent the truck off for a re-build and got the standard "master rebuild kit" done (Pistons, rods, crank, water pump, oil sender, balance, etc....). Also had banks headers thrown on, bbk throttle body, comp efi cam, and port matched everything.


Since I've got the truck back, it seems to have developed epilepsy or turrets. At any speed, highway, in-town, or idle, it will randomly do the following for about .5-1 second:


All gauges, accept tach, go to zero
Odometer display goes blank
ABS light comes on
Engine chokes


Like I said, it happens real quick, half second or second at the most, then immediately goes back to normal as if nothing ever happened.


I took the truck back to the builder and they said "It was a timing issue, so we put more timing in it. Should be fine now."
Sure enough, it did it twice again on the way home.


It's gotta be electrical, right?!


I've spent HOURS in the engine compartment looking for ANYTHING that looks out of place. I didn't find anything that would contribute to a problem like this.


The battery to engine ground looks solid, the battery to chassis ground looks solid, and the firewall/engine ground looks solid. The alternator is brand new, and I didn't have issue with it before the rebuild.


I can't find any other loose, frayed, or dangling wires.


I pulled the codes and got a TPS code, it was out of volt range, so I changed it. Volt readings are still a little high (1.4), but the idle is generally ok, and anyways, at driving speed the truck behaves normally until it spazzes.


I also got a 62C code, which the book says is for "cars only", for a transmission clutch fault.


I've looked all over the interwebs for someone with a similar problem, it seems this issue is a mechanical unicorn.


I need your help guys! Elk season is coming and I don't feel comfortable towing with this affliction!

 

Sounds like a bad connection but it could be hard to find. Have you tried wiggling wires around and seeing if you can duplicate the problem? It may or may not be related to something the mechanics did, but I'd check every connector that they might have disturbed. I'd also get under the dash and wiggle wires around and see if it stumbles.

 

https://www.ford-trucks.com/forums/1...-problems.html

X2 bashby, check these ground points courtesy of subford.

 

Bashby, I've followed just about every wire to its origin/end, but nothing. I haven't done the wiggle test with it running, and didn't think to try under the dash, those will be next. I'm about to the point of cutting open all the looms and checking for shorts.

Wag53, thanks man. I've checked all those grounds, except the ones by the kick panels, and by the EEC port (didn't know about that one). I'll check 'em and report back.

Thanks guys.

 

Did the wiggle test all over the engine compartment and under the dash while the truck was running, nothing changed.

All the ground wires, inside and out, are right where they should be.

Could it be I'm so unlucky to get a brand new alternator that has a screwy internal regulator?

I'm gonna take another day this week to painstakingly go over every connection, otherwise, it's off to the shop. I HATE not fixing stuff myself.

 

Alright, a delayed update;

After looking over every wire and harness I found the culprit. First, I found the builder routed the O2 sensor wire horribly. They wore down to bare metal rubbing against the EGR tubes, so replaced that.

But what I'm CERTAIN has been causing my electric issues was the starter wire was routed right next to the headers. Not close. Freaking right up against them, might was well have wrapped it around them.

Definitely a builder error, AND I've been fixing several wiring issues on my 1994 corvette the built also. Wont be going back to them.

I'm re-routing some new wire and should be good to go. I have some 4 gauge wire in the garage, you guys think that's hefty enough?

 

That's way bigger than 4 gauge. I'm not familiar with the gassers, but just looking at the pic, that looks like 0 or 2/0.

 

Nah, it's almost identical to the 4 gauge I have in the garage. This pic makes it look huge. I'll post a side by side pic when I get home.